The Study on Miniaturization and Weight Reduction of Auxiliary Power Unit in Magnetic Levitation Train

Lee, Na Ri,Shin, Hee Keun,Choi, Sung Ho,Kim, Ju Bum,Lim, Jae Won,Park, Doh Young,Mok, Hyung Soo The Korean Society for Railway 2015 International Journal of Railway Vol.8 No.1

Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.

Surgical Decision Making for the Elderly Patients in Severe Head Injuries

Lee, Kyeong-Seok,Shim, Jae-Jun,Yoon, Seok-Man,Oh, Jae-Sang,Bae, Hack-Gun,Doh, Jae-Won The Korean Neurosurgical Society 2014 Journal of Korean neurosurgical society Vol.55 No.4

Objective : Age is a strong predictor of mortality in traumatic brain injuries. A surgical decision making is difficult especially for the elderly patients with severe head injuries. We studied so-called 'withholding a life-saving surgery' over a two year period at a university hospital. Methods : We collected data from 227 elderly patients. In 35 patients with Glasgow Coma Score 3--8, 28 patients had lesions that required operation. A life-saving surgery was withheld in 15 patients either by doctors and/or the families (Group A). Surgery was performed in 13 patients (Group B). We retrospectively examined the medical records and radiological findings of these 28 patients. We calculated the predicted probability of 6 month mortality (IPM) and 6 month unfavorable outcome (IPU) to compare the result of decision by the International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) calculator. Results : Types of the mass lesion did not affect on the surgical decision making. None of the motor score 1 underwent surgery, while all patients with reactive pupils underwent surgery. Causes of injury or episodes of hypoxia/hypotension might have affected on the decision making, however, their role was not distinct. All patients in the group A died. In the group B, the outcome was unfavorable in 11 of 13 patients. Patients with high IPM or IPU were more common in group A than group B. Wrong decisions brought futile cares. Conclusion : Ethical training and developing decision-making skills are necessary including shared decision making.

Neuropathic Back Pain : Are There Any Practical Diagnostic Criteria?

Lee, Kyeong-Seok,Shim, Jae-Jun,Doh, Jae-Won,Yoon, Seok-Mann,Bae, Hack-Gun,Yun, Il-Gyu The Korean Neurosurgical Society 2007 Journal of Korean neurosurgical society Vol.41 No.1

Objective : A new point of view on the chronic back pain proposed which is, named neuropathic back pain[NBP]. Some proposed a certain pain scale as an useful diagnostic tool. Before scientific verification, some doctors prescribed a new anticonvulsant for the NBP. We investigated diagnostic tools for NBP by a review of the literature. Methods : A comprehensive computer search of the English literature concerning neuropathic low back pain was performed using the key words such as neuropathic back pain and diagnosis in the PubMed. Results : In 1998, the term NBP was first used in a patient with lung cancer. In the English literature, there were two diagnostic methods for the NBP, Neuropathic pain scale[NPS] and a pharmacological test. NPS is a pain questionnaire, which depends on the patients' subjective reports on the given questions, such as 'how hot is your pain feel'. By the pharmacological test, NBP was defined as 50% or more decrease of pain on intravenous lidocaine and on local anesthetic epidurally. It also depends on the patients' subjective response to the therapy. Conclusion : There were still no reliable objective diagnostic criteria for the NBP. It seems to be better to reserve the new anticonvulsants for the NBP till scientific approval.

Disability Evaluation of the Pain : The Present and Prospect in Korea

Lee, Kyeong-Seok,Shim, Jai-Joon,Yoon, Seok-Mann,Doh, Jae-Won,Yun, Il-Gyu,Bae, Hack-Gun The Korean Neurosurgical Society 2009 Journal of Korean neurosurgical society Vol.45 No.5

Objective : Pain has long been regarded as a subjective symptom. Recently, however, some regard a type of intractable chronic pain as a disease. Furthermore, chronic persistent pain becomes a cause of permanent impairment (PI) In 6th edition, the American Medical Association (AMA) Guides has rated the pain as a PI. In Korea, pain has been already been rated as a PI. Here, we examined the present status and the prospect of disability evaluation for the pain in Korea. Methods : Pain can be rated as a PI by the Workmen's Compensation Insurance Act (WCIA) and Patriots and Veterans Welfare Corporation Act (PVWCA) in Korea. We examined the definition, diagnostic criteria and grades of the pain related disability (PRD) in these two acts. We also examined legal judgments, which were made in 2005 for patients with severe pain. We also compared the acts and the judgments to the criteria of the 6th AMA Guides. Results : The PRD can berated as one of the 4 grades according to the WCIA. The provisions of the law do not limit the pain only for the complex regional pain syndrome (CRPS). The PRD can berated as one of the 3 grades by the PVWCA. If there were objective signs such as osteoporosis, joint contracture and muscle atrophy corresponding to the CRPS, the grade is rated as 6. When the pain always interferes with one's job except easy work,the grade is rated as high as 5. In Korea, judicial precedents dealt the pain a sa permanent disability in 2005. Conclusion : Although there were no objective criteria for evaluation of the PRD, pain has been already rated as a PI by the laws or judicial precedents, in Korea. Thus, we should regulate the Korean criteria of PRD like the AMA 6th edition. We also should develop the objective tools for evaluation of the PRD near in future.

Morphometric Study of the Lumbar Posterior Longitudinal Ligament

Lee, Sang Beom,Chang, Jae Chil,Lee, Gwang Soo,Hwang, Jae Chan,Bae, Hack Gun,Doh, Jae Won The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.1

Objective : Morphometric data for the lumbar posterior longitudinal ligament (PLL) was investigated to identify whether there is a difference in the morphometry of the PLL of the lumbar spine at each level with respect to the pattern of intervertebral disc displacement. Methods : In 14 formalin-fixed adult cadavers (12 males and 2 females), from L1 to L5, the authors measured the width and height of the PLL and compared them with other landmarks such as the disc and the pedicle. Results : Horizontally, at the upper margin of the disc, the central portion of the superficial PLL covered 17.8-36.9% of the disc width and the fan-like portion of the PLL covered 63.9-76.7% of the disc width. At the level of the median portion of the disc, the PLL covered 69.1-74.5% of the disc width. Vertically, at the level of the medial margin of the pedicle, the fan-like portion of the PLL covered 23.5-29.9% of the disc height. In general, a significant difference in length was not found in the right-left and male-female comparisons. Conclusion : This study presents the morphometric data on the pattern of intervertebral disc displacement and helps to improve the knowledge of the surgical anatomy of the lumbar PLL.

Suppression of Charge Recombination Rate in Nanocrystalline SnO₂ by Thin Coatings of Divalent Oxides in Dye-Sensitized Solar Cells

Lee, Chae-Hyeon,Lee, Gi-Won,Kang, Wee-Kyung,Lee, Doh-Kwon,Ko, Min-Jae,Kim, Kyoung-Kon,Park, Nam-Gyu Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.11

The core-shell $SnO_2$@AO (A=Ni, Cu, Zn and Mg) films were prepared and the effects of coatings on photovoltaic properties were investigated. Studies on X-ray photoelectron spectroscopy, energy dispersive X-ray analysis and transmission electron microscopy showed the formation of divalent oxides on the surface of $SnO_2$ nanoparticles. It was commonly observed that all the dye-sensitized core-shell films exhibited higher photovoltage than the bare $SnO_2$ film. Transient photovoltage measurements confirmed that the improved photovoltages were related to the decreased time constants for electron recombination.

Mapping of Quantitative Trait Loci Associated with Viviparous Germination in Rice

Lee, Seung-Yeob,Ahn, Jeong-Ho,Cha, Young-Soon,Yun, Doh-Won,Lee, Myung-Cheol,Eun, Moo-Young The Korean Society of Crop Science 2006 Korean journal of crop science Vol.51 No.6

The viviparous germination (VG) with lodging caused the yield reduction and quality deterioration in rice. We carried out the evaluation of VG tolerance (on the 40th day after heading) and mapping QTLs associated with VG tolerance using the recombinant inbred lines (M/G RILs) from a cross between Milyang 23 (japonica/indica) and Gihobyeo (japonica). The VG rates of Milyang 23 and Gihobyeo were 0.0 and 7.0%, respectively. The averaged VG rate of 162 M/G RILs was 7.7%, and their range was from 0.0 to 50.9%. Of the 162 RILs, 144 lines were tolerant less than 10%, and 18 lines were susceptible more than 10%. Using the M/G RIL Map, three QTLs associated with the viviparous trait were detected on chromosome 2 (qVG 2-1 and qVG 2-2) and 8 (qVG 8). qVG 2-1 was linked to RM 32D and RZ 166, and had LOD score of 2.97. qVG 2-2 was tightly linked to E13M59.119-Pl and E13M59.M003-P2, and showed higher LOD score of 3.41. qVG 8 was linked to RM33 and TCT116, and had LOD score of 2.67. The total phenotypic variance explained by the three QTLs was about 24.4% of the total variance in the population. The detection of new QTLs associated with VG tolerance will provide important informations for the seed dormancy, low temperature germination, or comparative genetics.

Work function engineering of SnO single crystal microplates with thermal annealing

Doh, Won Hui,Jeong, Wooseok,Lee, Hyunsoo,Park, Jonghyurk,Park, Jeong Young IOP 2016 Nanotechnology Vol.27 No.33

<P>We synthesized black SnO single-crystal microplates via a sonochemical process and engineered the work function of the SnO microplates using thermal treatments. The as-synthesized SnO microplates have a wide (001) plane, as is clearly evident from TEM images and diffraction patterns. Surface potential measurements on the SnO microplates show that the work function changes as the annealing temperature increases. The TEM and XAS results after thermal treatments imply that the micro-sized SnO(001) single-crystals are stable up to about 400 °C in air, after which the surface starts to become locally oxidized. Consequently, the long-range ordering and lattice parameter of the SnO(001) single crystals started to change to make polycrystalline SnO<SUB>2</SUB> at about 600 °C. These results demonstrate the ability to tune the work function of the microplates and suggest an intriguing way to engineer the electrical properties of nanostructures.</P>

Work function engineering of SnO single crystal microplates with thermal annealing

Won Hui DOH,Wooseok JEONG,Hyunsoo LEE,Jonghurk PARK,Jeong Young PARK 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.8

Nanoscale Friction on Confined Water Layers Intercalated between MoS₂ Flakes and Silica

Lee, Hyunsoo,Jeong, Hochan,Suh, Joonki,Doh, Won Hui,Baik, Jaeyoon,Shin, Hyun-Joon,Ko, Jae-Hyeon,Wu, Junqiao,Kim, Yong-Hyun,Park, Jeong Young American Chemical Society 2019 The Journal of Physical Chemistry Part C Vol. No.

<P>Frictional energy dissipation at the interfaces of two-dimensional (2D) materials through the excitation and transfer processes of kinetic energy into the bulk can be easily influenced by an intercalated water film. An enhancement of friction on water-intercalated graphene has been observed. Is this frictional enhancement by confined water a general phenomenon? We address this issue by investigating the frictional behavior of confined water layers intercalated between single-layer molybdenum disulfide (MoS<SUB>2</SUB>), synthesized using chemical vapor deposition, and a silica substrate. The icelike water was intercalated by exposure to high-humidity air. We found that the intercalated water molecules morphologically deform the 2D MoS<SUB>2</SUB> sheet, forming distinct subdomains after the exposure to high humidity. We found that the adsorption of the icelike water layer between the MoS<SUB>2</SUB> and the silica leads to friction enhancement, compared with a pristine MoS<SUB>2</SUB>/silica sample, which is associated with additional phononic friction energy dissipation at the solid-liquid interface, as indicated by the phonon distribution analysis from the empirical force-field calculations. Moreover, the atomic stick-slip behavior shows that the lattice orientation of the hydrophilic MoS<SUB>2</SUB> affects water molecule diffusion at the interface of the MoS<SUB>2</SUB>/silica substrate. Chemical mapping of the water-intercalated MoS<SUB>2</SUB> on silica using scanning photoelectron microscopy and vacuum annealing processes shows water intercalation without changing the intrinsic composition of the MoS<SUB>2</SUB> on silica.</P> [FIG OMISSION]</BR>