• 한국자동차공학회논문집
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• 제5권2호
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• pp.50-59
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• 1997

When a front head of train enters a tunnel at a high speed, compression wave is generated at tunnel entrance due to the confinement effect and propagated along the tunnel with sound of speed. The propagated compression wave is reflected at tunnel exit due to abrupt pressure change at passage. The reflected wave is expansion pressure wave. And when the rear head of train goes through the tunnel entrance, another expansion pressure wave is generated and propagated along the tunnel. The pressure drop occurs seriously around train when the two expansion pressure waves come cross on train in the tunnel. In order to reduce the pressure drop, the compression wave front must be controlled because the intensity and magnitude of pressure drop is nearly proportional to that of compression wave at tunnel entrance. This study relates to reduction of the pressure wave gradient with respect to tunnel entrance shape change with various kind of angle and rounding. The results show characteristics of wave propagation in tunnel, usefulness of characteristic curve to estimate proper time domain size in numerical study and measuring time in actual experiment. Also rounding is contributed to improve pressure wave front even if its radius is very small at tunnel entrance. In order to improve of pressure wave front at tunnel entrance, proper angle is prefered to rounding with big radius and an angle of around 14$^{\circ}$ is recommended according to this simulations, And it is expected to reduce additional pressure drop in tunnel when the location and the size of the internal space for attendant equipment are considered in advance.

• 대한기계학회논문집
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• 제17권2호
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• pp.285-299
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• 1993

본 연구에서는 UBET를 이용한 프로그램을 개발하여 소성가공 문제에 적용하였 으며, 형단조 가공에서 형 내부의 재료의 비정상 유동을 해석할 수 있는 알고리듬을 제시하였다. 매 변형단계에서 요소별 가공경화를 고려하여 자동적으로 요소시스템 (element system)을 재구성함으로써, UBET에 의한 소성가공 문제 해석을 효율적으로 할 수 있도록 하였다. 축대칭 형단조 문제에 있어서 리브의 높이대 폭의 비가 1.0, 2.0일때 UBET 및 탄소성 유한요소법에 의하여 형 내부의 재료 층만 과정을 시뮬레이션 하였으며, 단조 하중, 다이 충만도 및 재료의 유동 경향을 분석하여 적절한 유동 모델 과 초기 소재의 형상을 구하였다. 모델 재료를 사용한 형단조 모의실험을 수행하여 재료유동 및 변형 단계별 단조 하중분포 등을 구하였으며, 해석결과와 비교 분석하였 다. 또한 후방압출(backward extrusion) 및 평두형 펀치에 의한 평판압입(flat pu- nch indentation) 문제를 해석하였다. 후방압출시 모서리부의 라운딩(rounding) 효 과가 재료 유동에 미치는 영향을 고려하였으며, 평두형 펀치에 의한 평판압입에서는 상당 소성변형률(equivalent plastic strain)의 분포를 탄소성 유한요소법(elastic plastic finite element method)에 의한 결과와 비교하였다.

• 대한치과보철학회지
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• 제49권1호
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• pp.22-28
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• 2011

연구 목적: 지르코니아 보철물을 위한 치아 형성이 실제 임상에서 어떻게 이루어지는지에 대해 조사하고 향후 치아 형성에 대한 교육 자료 및 추가 연구의 기초 자료로 활용하고자 한다. 연구 재료 및 방법: 지르코니아 치관 제작을 위해 milling center에 보내진 모형을 조사하여 Lava CAD/CAM System으로 스캔 한 후 'ImageJ' 프로그램 상에서 측정하여, 이를 비교 분석하였다. 각 치아마다 근원심면과 협설면에서의 축면 경사각을 측정하였다. 또한, 견치를 제외한 전치에서 절단연 0.4 mm 하방 부위의 bucco-lingual diameter 측정하였다. 결과 및 결론: 실험군 내에서 지르코니아 전부도재관을 위한 지대치의 축면 경사각은 $18.67^{\circ}$로 문헌에서 추천하는 각도 보다 크게 나타났다. 지르코니아 완전도재관의 지대치 형성 시 축면 경사각은 협설과 근원심면, 악궁 내 위치에 따라 차이가 있었다. Peak 0.4의 평균값은 1.18 mm로 밀링버의 최소직경을 고려한 요구조건인 0.8 mm 보다 큰 값으로 나타났다. 그러나 선각 부위 rounding 에 관한 추가적인 연구가 필요할 것으로 생각된다.

• 한국직업건강간호학회지
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• 제15권2호
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• pp.133-143
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• 2006

Purpose: The purpose of this study was to examine the relationship between perceived job stress and work environmental factors related with socioeconomics factors and physical burden in the golf caddies. Methods: Job stress in golf caddies was estimated by using the Karasek's job content questionnaire (JCQ) and work environmental factors were estimated by self-reported questionnaire and interview. Results: The subjects were 316 woman caddies who had never been occupationally exposed to hazardous chemicals, was mean age 31.1 years. Mean work duration was 6.44 years and working hours per day on low- and high-demand season were 6.16 and 10.51, respectively. The golf caddies displayed higher scores of job stress due to multiple factors such as working hours and frequency of rounding per week, physical burden, confliction, income satisfaction and employment stability. We found that high strain group was positive correlation with age, career, working hour (including frequency of rounding) and job demand, however, showed negative correlation with job decision latitude and support of supervisor and coworker. Conclusion: In conclusion, we suggest that the golf caddies be regard divided into high strain group as appropriate. Thus, stress management and health promotion program for golf caddies should be developed.

• 생명과학회지
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• 제17권10호
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• pp.1361-1367
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• 2007

Nocardiopis sp. 유래의 protein kinase 저해제인 KT5720, KT5926을 사용하여 Vesicular Stomatitis Virus (VSV) 증식에 미치는 세포변성의 억제를 지표로서 연구하였다. 그 결과 CAMP의존 kinase를 저해하는 KT5720, mysion light chain kinase (MLCK)를 저해하는 KT5926이 VSV에 의한 세포변성을 억제시켰다. Protein kinase inhibitor KT5720은 VSV의 증식에 영향을 미치지는 않지만, 세포변성과정은 억제하는 것으로 나타났다. Virus RNA 및 단백질 합성에서 PKA KT5720이 영향을 미치지 않는 것은 virus 증식에 영향이 없는 것으로 나타난다. Virus 증식과정에서 성질이 다른 protein kinase가 관여하는데, 이것은 negative strand virus에 대한 항virus 제 개발에 중요한 역할을 한다고 생각한다.

• 말소리와 음성과학
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• 제7권1호
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• pp.79-86
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• 2015

This study explored the vowel effect on acoustic perturbation measures in voice quality analysis. For this study, the perturbation parameters (%jitter, %shimmer) and noise parameter (SNR) were measured with 7 Korean vowels (/a/, /ɛ/, /i/, /o/, /u/, /ɯ/, /ʌ/) using CSpeech with 50 Korean normal young adults (24 males and 26 females). A significant vowel effect was found only in %shimmer and in particular, low-back /a/vowel was significantly different from other vowels in %shimmer. The least perturbation and noise were exhibited on high-back /ɯ/ and /o/ vowel, respectively. Based on tongue height, a significant higher %shimmer was demonstrated on low vowels than high vowels. In addition, back vowels in tongue advancement and rounded vowels in lip rounding showed significantly less perturbation and noise. The least variability of perturbation and noise within individuals was demonstrated on the vowel /i/ in three repeated measures. However, there was no significant difference among 3 token measures in single session among vowels tested except the vowel /o/. Consequently, the vowel /a/ commonly used in acoustic perturbation measures exhibited higher perturbation and noise whereas higher stability and less variability were demonstrated on the high-back vowel /u/. These results suggested that the Korean high-back vowel /u/ can be more appropriate and reliable for perturbation acoustic measures.

• 한국음향학회지
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• 제6권2호
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• pp.30-37
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• 1987

한글 단모음의 음향특성을 기본진동수와 배진동수를 고러하여 포만트 분석하였으며, 성도내의 공명현상과 포만트진동수와의 상관관계를 고찰하였다. 성악을 전공하는 남성으로 하여금 한글 단모음 12개를 5개의 기본진동수에 맞추어 3초 동안 발음하게 하여 FFT스펙트럼 분석기를 통해 진동수 스펙트럼을 얻었다. 포만트 분석에 의해 제 1포만트는 인두강, 그리고 제 2포만트는 구강의 공명효과에 의함을 밝혔고, 원순화가 일어나므로서 제 2포만트 진동수가 낮아짐을 발견하였다. 제 1포만트와 제 2포만트 진동수로는 "어"의 $[\partial]와[\Lambda], "아"의[a]와 [\alpha]$, 그리고"에"와 "애"의 음향학적 차이를 뚜렷이 구분짓기는 어러웠다

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.125-132
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• 2002

PMSMS (permanent magnet synchronous motors) are widely used in industrial applications and home appliances because of their high torque to inertia ratio, superior power density, and high efficiency. For high performance control, accurate informations about the rotor position is essential. Sensorless algorithms have lately been studied extensively due to the high cost of position sensors and their low reliability in harsh environments. A novel position sensorless speed control for PMSMs uses indirect flux estimation and is presented in this paper. Rotor position and angular velocity are estimated by the proposed indirect flux estimation. Linkage flux and magnetic field flux are calculated by the voltage equations and the measured phase current without any integration. Instead of linkage flux calculation with integral operation, indirect flux and differential magnetic field are used for the estimation of rotor position. A proper rejection technique fur current noise effect in the calculation of differential linkage flux is introduced. The proposed indirect flux detecting method is free from the integral rounding error and linkage flux drift problem, because differential linkage flux can be calculated without any integral operation. Furthermore, electrical parameters of the PMSM can be measured by the proposed TCM (time compression method) for soft starting and precise estimation of rotor position. The position estimator uses accurate electrical parameters that are obtained from the proposed TCM at starting strategy. In the operating region, a proper compensation method fur temperature effect can compensate fir the estimation error from the variation of electrical parameters. The proposed novel position sensorless speed control scheme is verified by the experimental results.

• 대한전자공학회논문지SD
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• 제47권3호
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• pp.1-6
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• 2010

Saddle MOSFET의 모서리의 효과에 대한 고전역학과 양자역학적 시뮬레이션의 비교분석을 3차원 수치 시뮬레이터를 사용하여 수행하였다. 비교분석 결과 양자역학적 시뮬레이션에서는 실리콘 핀의 단면에서의 정확한 최대 전자 밀도의 위치와 크기를 제공함으로써 소자의 정확한 설명을 제공하는 것을 보여 주었고, 이를 이용하여 모서리 효과 및 그것이 소자의 문턱전압의 특성을 미치는 영향의 정확한 분석이 실행되었다. 또한, 모서리 효과를 억제하기 위해서 실리콘 핀의 모서리를 둥글게 하거나 구석의 바디도핑을 낮추는 두 가지 가능한 기법을 제시했다.

• 한방안이비인후피부과학회지
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• 제19권2호
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• pp.26-39
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• 2006

Objective : The effect of water extract of Chungjogupae-tang (CJGPT) was investigated on the growth of human lung carcinoma A549 cells. Methods : MTT assay and fluorescent microscope performed to compare and examine the efficacy of CJGPT treatment on the cytostaticity of lung cancer cells in proportion to time and doses, and DAPI staining and Western blot analysis were used to examine their effect on apoptosis. In addition the quantitative RT-PCR was used to examine to lung cancer cells growth and Progtaglandin E2 and Telomerase activity were measured Results : Exposure of A549 cells to CJGPT resulted in the growth inhibition and apoptosis in a dose-dependent manner as measured by MTT assay and fluorescent microscope. The antiuoliferative effect by CJGPT treatment in A549 cells was associated with morphological changes such as membrane shrinking and cell rounding up. CJGPT treatment resulted in an up-regulation of cyclin-dependent kinase inhibitor p21(WAF1/CIPl) in a p53-independent fashion. We found that CJGPT treatment decreased the levels of cyclooxygenase (COX)-2 and inducible nitric oxide synthease (iNOS) expression without significant changes in the expression of COX-1, which was correlated with a decrease in protaglandin E2 (PGE2) synthesis. CJGPT treatment also inhibited the levels of human telomerase reverse transcriptase (hTERT) and telomerase-associated protein (TEP)-1 mRNA expression, however the activity of telomerase was slightly increased by CJGPT treatment. Conclusion : These findings suggested that CJGPT-induced inhibition of human lung carcinoma A549 cell growth was connected with the induction of apoptotic cell death and the results provided important new insights into the possible molecular mechanisms of the anti-cancer activity of CJGPT.