Creat membership Creat membership
Sign in

Forgot password?

  • Forgot password?
    Sign Up
  • Confirm
    Sign In
home > search

Now showing items 1 - 16 of 33500

  • Supernova Neutrino Process of Li and B Revisited

    Kusakabe, Motohiko   Cheoun, Myung-Ki   Kim, K. S.   Hashimoto, Masa-aki   Ono, Masaomi   Nomoto, Ken’ichi   Suzuki, Toshio   Kajino, Toshitaka   Mathews, Grant J.  

    Download Collect
  • Simulation of single grid-based phase-contrast x-ray imaging(g-PCXI)

    Lim, H. W.   Lee, H. W.   Cho, H. S.   Je, U. K.   Park, C. K.   Kim, K. S.   Kim, G. A.   Park, S. Y.   Lee, D. Y.   Park, Y. O.   Woo, T. H.   Lee, S. H.   Chung, W. H.   Kim, J. W.   Kim, J. G.  

    Single grid-based phase-contrast x-rayimaging (g-PCXI) technique, which was recently proposed by Wen et al. to retrieve absorption, scattering, and phase-gradient images from the raw image of the examined object, seems a practical method for phase-contrast imaging with great simplicity and minimal requirements On the setup alignment. In this work, we developed a useful simulation platform for g-PCXI and performed a simulation to demonstrate its viability. We also established a table-top setup for g-PCXI which consists of a focused-linear grid (200-lines/in strip density), an x-ray tube (100- mu m focal spot size), and a flat-panel detector (48-pm pixel size) and performed a preliminary experiment with some samples to show the performance of the simulation platform. We successfully obtained phase -contrast x-ray images of much enhanced contrast from both the simulation and experiment and the simulated contract seemed similar to the experimental contrast, which shows the performance of the developed simulation platform. We expect that the simulation platform will be useful for designing an optimal g-PCXI system.
    Download Collect
  • Estimating total fusion cross sections by using a coupled-channel method

    Choi, Ki-Seok   Cheoun, Myung-Ki   Kim, K. S.   Kim, T. H.   So, W. Y.  

    We calculate the total fusion cross sections for the He-6 + Bi-209, Li-6 + Bi-209,Be-9 + Pb-208, Be-10 + Bi-209, and Li-11 + Pb-208 systems by using a coupled-channel (CC) method and compare the results with the experimental data. In the CC approach for the total fusion cross sections, we exploit a globally determined Wood-Saxon potential with Akyuz-Winther parameters and couplings of the ground state to the low-lying excited states in the projectile and the target nuclei. The total fusion cross sections obtained with the CC are compared with those obtained without the CC couplings. The latter approach is tantamount to a one-dimensional barrier penetration model. Finally, our approach is applied to understand new data for the Li-11+Pb-208 system. Possible ambiguities inherent in those approaches are discussed in detail for further applications to the fusion system of halo and/or neutron-rich nuclei.
    Download Collect
  • Fission Chain Restart Theory

    Kim, K. S.   Nakae, L. F.   Prasad, M. K.   Snyderman, N. J.   Verbeke, J. M.  

    Download Collect

    Yang, S. M.   Yoo, S. H.   Gi, D. S.   Choi, S. B.   Kim, K. S.   Jeong, N. T.   Choi, S. U.   Suh, M. W.   Lee, J. H.  

    While a screw is a fastening element that can tighten the two parts at low cost, the loosening of the screw is generated due to external forces such as repetitive load, vibration, and thermal stress. This phenomenon decreases the initial clamping force, and this can be a serious problem to the safety of the product. However, while fastening parts are handled through experiment and experience, there is a lack of research on the screw loosening of plastic fastening parts. For example, vehicles have various fastening parts. Among the fastening elements, screws are typically used for tightening parts of the vehicle door trim. Vehicle interior materials are mainly composed of plastic parts. Especially, the temperature of the vehicle interior changes from a sub-zero temperature to 100 degrees (degrees C) due to solar radiation. Unlike metals, plastic materials are commonly susceptible to the environment. In this study, the fastening screw of automotive door trim parts is selected. First, a screw loosening mechanism is implemented through Computer Aided Engineering (CAE) analysis and the influences of degradation are then analyzed. Secondly, the selecting method of clamping force is suggested through the analysis result of reduction according to the tightening torque.
    Download Collect
  • Effects of Coulomb quadrupole excitation in heavy-ion reactions

    Cheoun, Myung-Ki   Choi, K. S.   Kim, K. S.   Kim, T. H.   So, W. Y.  

    For C-12 + W-184, O-18 + W-184, and Ne-20 + Pb-208 systems, we investigate the suppression of the ratios P (E) =3D sigma (el)/sigma (RU) by using the Coulomb quadrupole excitation (CQE) potentials. In order to explain the effect of the CQE potentials, we first use a well-known Love's CQE potential, and reproduce the experimental P (E) data well by using this potential. We also introduce a simple CQE potential written as W (CQE)(r) =3D -W (P) /r (n) , which is much simpler than the conventional Love's potential, to investigate the suppression of the P (E) ratios. Using this potential, we perform a chi(2) analysis to find the adjustable parameter n, then, we find that the best fit parameters n ae 5 is close to the lowest order term, 1/r (5). Consequently, we find that using the simple CQE potential explains the experimental P (E) data and that the ratio P (E) depends on the n values sensitively.
    Download Collect
  • Optimal assessment of lymph node status in gallbladder cancer

    Kim, S. H.   Chong, J. U.   Lim, J. H.   Choi, G. H.   Kang, C. M.   Choi, J. S.   Lee, W. J.   Kim, K. S.  

    Background: Lymph node (LN) metastasis is an important prognostic factor in gallbladder cancer (GBCA). LN status has been adopted as a critical element of staging systems. However, the influence of total lymph node count (TLNC) remains unclear. We determined the optimal minimum TLNC and compared the prognostic significance of LN status indices in GBCA. Methods: We retrospectively reviewed medical records of 128 patients with T2 or greater GBCA who underwent LN dissection. We analyzed overall survival (OS) and relevance of the number of metastatic LNs, ratio of metastatic LNs to retrieved LNs (LNR), and TLNC in predicting OS. Results: The median OS durations were 120, 35, and 18 months in T2, T3, and T4 GBCA. Five-year OS rates were 73%, 43%, and 0% in T2, T3, and T4 GBCA. LN status did not significantly impact OS in T2 or T4 GBCA. However, all LN indices were significantly correlated with OS in T3 GBCA. Furthermore, multivariate analysis revealed that a metastatic LN count of more than four and a TLNC of more than eight were independent prognostic factors of OS in T3 GBCA. Conclusions: TLNC and the number of positive LNs may be more important prognostic factors than LNR in T3 GBCA. Additionally, accurate staging may not be achieved in cases of T3 GBCA if the total number of retrieved LNs is less than eight. Thus, to ensure proper staging, we recommend that surgeons harvest more than eight LNs in patients with T3 GBCA. (C) 2015 Elsevier Ltd. All rights reserved.
    Download Collect

    Jeong, N. T.   Yang, S. M.   Kim, K. S.   Wang, M. S.   Kim, H. S.   Suh, M. W.  

    Nowadays, a number of environmental issues have seriously come to the fore. For this reason, the R & D spending on eco-friendly vehicles that use electric power has been gradually increasing. In general, fuel economy and pollutant emissions of both conventional and eco-friendly vehicles are measured through chassis dynamometer tests that are performed on a variety of driving cycles before an actual driving test. There are a number of driving cycles that have been developed for the for performance evaluation of conventional vehicles. However, there is a lack of research into driving cycle for EV. Because large differences exist between the drive system and driving charateristics of EV and that of CV, a study on driving cycle for EV should be conducted. In this study, the necessity of an urban driving cycle for the performance evaluation of electric vehicles is confirmed by developing the driving cycle. First, the Gwacheon-city Urban Driving Cycle for Electric Vehicles (GUDC-EV) is developed by using driving data obtained through actual driving experiments and statistical analysis. Second, GUDC-EV is verified by constructing EV simulators and performing simulations that use the actual driving data. The simulation results are then compared against existing urban driving cycles, such as FTP-72, NEDC, and Japan 10-15. These results confirm that GUDC-EV can be used as an urban driving cycle to evaluate the performance of electric vehicles and validate the necessity of development of the driving cycle for electric vehicles.
    Download Collect

    Yoo, S. H.   Jeong, N. T.   Kim, K. S.   Yang, S. M.   Lee, J. H.   Choi, S. H.   Suh, M. W.  

    The use of plastic in vehicle development has increased. In particular, a design trend has resulted in chromium-plated plastics being used in exterior panels. Recently, as the appearance has become more important in design, the plastic radiator grille has become larger, to where it can become the primary member when a front collision happens. The radiator grille should be designed with considerations of the geometric structure, such as delamination, and material characteristics, when plastics are plated with chromium. The enlarged grille has to pass regulations like FMVSS Part 581. Although the material property of plastic has been studied before, what seems to be lacking is study on the crashworthiness of plastic radiator grilles that are plated using chromium. In this paper, in order to evaluate the crashworthiness, tensile test and front collision analysis using finite element method are performed. Tensile test is conducted with 4 types of materials, and then material properties of chromium-plated plastics are obtained. Meanwhile radiator grille's crashworthiness is evaluated using finite element analysis method. Analysis result is evaluated according to failure criterion. Through this study, method of the assessment of plastic radiator grille's crashworthiness considered material properties of chromium plated plastics is proposed, and it can be predicted the delamination and the failure point of radiator grille at the design step.
    Download Collect

    Wang, M. S.   Jeong, N. T.   Kim, K. S.   Choi, S. B.   Yang, S. M.   You, S. H.   Lee, J. H.   Suh, M. W.  

    Drowsy behavior is more likely to occur in sleep-deprived drivers. Individuals' drowsy behavior detection technology should be developed to prevent drowsiness related crashes. Driving information such as acceleration, steering angle and velocity, and physiological signals of drivers such as electroencephalogram (EEG), and eye tracking are adopted in present drowsy behavior detection technologies. However, it is difficult to measure physiological signal, and eye tracking requires complex experiment equipment. As a result, driving information is adopted for drowsy driving detection. In order to achieve this purpose, driving experiment is performed for obtaining driving information through driving simulator. Moreover, this paper investigates effects of using different input parameter combinations, which is consisted of lateral acceleration, longitudinal acceleration, and steering angles with different time window sizes (i.e. 4 s, 10 s, 20 s, 30 s, 60 s), on drowsy driving detection using random forest algorithm. 20 s-size datasets using parameter combination of accelerations in lateral and longitudinal directions, compared to the other combination cases of driving information such as steering angles combined with lateral and longitudinal acceleration, steering angles only, longitudinal acceleration only, and lateral acceleration only, is considered the most effective information for drivers' drowsy behavior detection. Moreover, comparing to ANN algorithm, RF algorithm performs better on processing complex input data for drowsy behavior detection. The results, which reveal high accuracy 84.8 % on drowsy driving behavior detection, can be applied on condition of operating real vehicles.
    Download Collect
  • Report on recent results of the PERCIVAL soft X-ray imager

    Khromova, A.   Cautero, G.   Giuressi, D.   Menk, R.   Pinaroli, G.   Stebel, L.   Correa, J.   Marras, A.   Wunderer, C. B.   Lange, S.   Tennert, M.   Niemann, M.   Hirsemann, H.   Smoljanin, S.   Reza, S.   Graafsma, H.   Goettlicher, P.   Shevyakov, I.   Supra, J.   Xia, Q. d   Zimmer, M.   Guerrini, N.   Marsh, B.   Sedgwick, I.   Nicholls, T.   Turchetta, R.   Pedersen, U.   Tartoni, N.   Hyun, H. J.   Kim, K. S.   Rah, S. Y.   Hoenk, M. E.   Jewell, A. D.   Jones, T. J.   Nikzad, S.  

    The PERCIVAL (Pixelated Energy Resolving CMOS Imager, Versatile And Large) soft X-ray 2D imaging detector is based on stitched, wafer-scale sensors possessing a thick epi-layer, which together with back-thinning and back-side illumination yields elevated quantum efficiency in the photon energy range of 125-1000 eV. Main application fields of PERCIVAL are foreseen in photon science with FELs and synchrotron radiation. This requires high dynamic range up to 105 ph @ 250 eV paired with single photon sensitivity with high confidence at moderate frame rates in the range of 10-120 Hz. These figures imply the availability of dynamic gain switching on a pixel-by-pixel basis and a highly parallel, low noise analog and digital readout, which has been realized in the PERCIVAL sensor layout. Different aspects of the detector performance have been assessed using prototype sensors with different pixel and ADC types. This work will report on the recent test results performed on the newest chip prototypes with the improved pixel and ADC architecture. For the target frame rates in the 10-120 Hz range an average noise floor of 14 e(-) has been determined, indicating the ability of detecting single photons with energies above 250 eV. Owing to the successfully implemented adaptive 3-stage multiple-gain switching, the integrated charge level exceeds 4 . 10(6) e-or 57000 X-ray photons at 250eV per frame at 120 Hz. For all gains the noise level remains below the Poisson limit also in high-flux conditions. Additionally, a short overview over the updates on an oncoming 2 Mpixel (P2M) detector system (expected at the end of 2016) will be reported.
    Download Collect
  • Spin-1 diquark contributing to the formation of tetraquarks in light mesons

    Kim, Hungchong   Cheoun, Myung-Ki   Kim, K. S.  

    We apply a mixing framework to the light meson systems and examine tetraquark possibility in the scalar channel. In the diquark-antidiquark model, a scalar diquark is a compact object when its color and flavor structures are in ((3) over bar (c), (3) over bar (f)). Assuming that all the quarks are in an S-wave, the spin-0 tetraquark formed out of this scalar diquark has only one spin configuration, vertical bar J, J(12), J(34) > =3D vertical bar 000 >, where J is the spin of the tetraquark, J(12) the diquark spin, J(34) the antidiquark spin. In this construction of the scalar tetraquark, we notice that another compact diquark with spin-1 in (6(c), (3) over bar (f)) can be used although it is less compact than the scalar diquark. The spin-0 tetraquark constructed from this vector diquark leads to the spin configuration vertical bar J, J(12), J(34) > =3D vertical bar 011 >. The two configurations, vertical bar 000 and vertical bar 011 >, are found to mix strongly through the color-spin interaction. The physical states can be identified with certain mixtures of the two configurations which diagonalize the hyperfine masses of the color-spin interaction. Matching these states to two scalar resonances a(0)(980), a(0)(1450) or to K-0*(800), K-0*(1430) depending on the isospin channel, we find that their mass splittings are qualitatively consistent with the hyperfine mass splittings which can support their tetraquark structure. To test our mixing scheme further, we also construct the tetraquarks for J=3D1, J=3D2 with the spin configurations, vertical bar 111 > and vertical bar 211 >, and discuss possible candidates in the physical spectrum.
    Download Collect
  • Possible signatures for tetraquarks from the decays of a(0)(980),a(0)(1450)

    Kim, K. S.   Kim, Hungchong  

    Based on the recent proposal for the tetraquarks with the mixing scheme, we investigate fall-apart decays of a(0)(980), a(0)(1450) into two lowest-lying mesons. This mixing scheme suggests that a(0)(980) and a(0)(1450) are the tetraquarks with the mixtures of two spin configurations of diquark and antidiquark. Due to the relative sign differences in the mixtures, the couplings of fall-apart decays into two mesons are strongly enhanced for a(0)(980) but suppressed for a(0)(1450). We report that this expectation is supported by their experimental decays. In particular, the ratios of the associated partial decay widths, which depend on some kinematical factors and the couplings, are found to be around Gamma[a(0)(980) -> pi eta]/ Gamma[a(0)(1450) -> pi eta] =3D 2.51 - 2.54, Gamma[a(0)(980) -> K (K) over bar]/Gamma[a(0)(1450) -> K (K) over bar] =3D 0.52 - 0.89, which seems to agree with the experimental ratios reasonably well. This agreement can be interpreted as the tetraquark signatures for a(0)(980), a(0)(1450).
    Download Collect
  • Removal of solitary neurofibroma of the external nose by intranasal approach

    Min, H. J.   Kim, K. S.  

    Introduction: Solitary neurofibroma originating from the external nose is extremely rare, and to our knowledge, only 3 cases have been reported so far in English literatures. It may originate from the ophthalmic (V1) and maxillary (V2) branches of the trigeminal nerve. Case report: We present a rare case of solitary neurofibroma arising from the external nose, which was successfully removed by intranasal approach with intercartilaginous incision. Conclusion: This case emphasizes two important points. First, we should keep in mind that this clinical entity is included in the differential diagnosis of soft tissue masses arising from the external nose. Second, we should choose the best surgical approach for complete removal with the maintenance of cosmetic appearance. (C) 2017 Elsevier Masson SAS. All rights reserved.
    Download Collect
  • Robust Filtering for Discrete Systems with Unknown Inputs and Jump Parameters

    Kim, K. S.   Smagin, V. I.  

    Download Collect
  • Neonatal Bacterial Meningitis

    Kim, K. S.  

    Download Collect
1 2 3 4 5 6 7 8 9 10


If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

Submit Feedback