Economic Feasibility Analysis of Integrated Food Security Project, in Teuk Phos District, Kampong Chhnang Province, Cambodia

Sim Boramy,Yongdae Kwon,Seungmo Koo 한국국제농업개발학회 2009 韓國國際農業開發學會誌 Vol.21 No.1

다결정 실리콘 스트레인 게이지의 저항 계수

김용대(Yongdae Kim),권세진(Sejin Kwon) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

The performance of polysilicon strain gauges before and after heat treatment along with the conventional metal annealing process and the glass-frit bonding process was evaluated to investigate effect of the glass-frit bonding process. The gauge factors of the poly-silicon strain gauges that were not heat treated were determined by multiplying the resistivity coefficient of gauge factor (RCGF) and resistivity. The RCGF, which is new coefficient derived in our research, presents the resistivity dependence of the gauge factor of the polysilicon strain gauge. The gauge factors of a poly-silicon strain gauges heat treated with aluminum annealing process and glass-frit bonding process equaled the RCGF multiplying resistivity of the gauge. This RCGF was same with that of the strain gauges that were not heat treated.

크롬실리사이드를 이용한 고온용 스트레인 게이지의 제작 및 성능평가

김용대(Yongdae Kim),박현철(Hyunchul Park),권세진(Sejin Kwon) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

The stress analysis which is for measurement of the stress distribution in materials and structures subjected to static or dynamic forces or loads relies commonly on the strain measurement techniques since stress can be calculated by using stress-strain relationships. By far the most widely used devices for measurement of strain is a metal foil strain gauge. However, a limitation of the metal foil used as strain gauges is that their resistance changes as the temperature changes. This result that the metal foil gauge cannot be used for strain measurements of structures at the high temperature environment. On the other hand, the strain gauge made with chromium silicide is suitable to measure strain at the high temperature environment because chromium silicide has relatively low TCR (Temperature Coefficient of Resistance).

금속 외팔보에 접착된 박막 실리콘 스트레인 게이지의 제작 및 성능 평가

김용대(Yongdae Kim),김영덕(Young Deok Kim),이철섭(Chul Sub Lee),권세진(Sejin Kwon) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.4

금속은 가공성이 우수하기 때문에 다양한 형태의 구조물이나 격막을 제작할 수 있다. 이런 금속구조물이나 격막에 민감도가 월등히 우수한 실리콘 스트레인 게이지를 적용할 경우 그 응용 범위가 다양해질 수 있다. 이에 금속구조물에 다결정 실리콘 스트레인 게이지를 접착한 형태의 센서를 제안하였다. 실리콘 기판을 이용해 박막형 다결정 실리콘 스트레인 게이지를 제작하기 위한 제작공정을 확립하였으며, 제작된 실리콘 스트레인 게이지를 금속 변형부 위에 접착하기 위한 접착공정을 확립하였다. 이후 금속 외팔보에 실리콘 스트레인 게이지를 글래스 프릿 접착하여 성능평가를 실시하였다. 성능평가 결과 게이지팩터는 34.0의 값을 가졌으며, TCR(Temperature Coefficient of Resistance)은 -328 ppm/℃의 값을 가졌다. In this paper, we propose a sensor design by using a polysilicon strain gauge bonded to a metal diaphragm. The fabrication process of the thin polysilicon strain gauges having thicknesses of 50 μm was established using conventional MEMS technologies; further, the technique of glass frit bonding of the polysilicon strain gauge to the stainless steel diaphragm was established. Performance of the polysilicon strain gauge bonded to the metal cantilever beam was evaluated. The gauge factor, temperature coefficient of resistance (TCR), nonlinearity, and hysteresis of the polysilicon strain gauge were measured. The results demonstrate that the resistance increases linearly with tensile stress, while it decreases with compressive stress. The value of the gauge factor, which represents the sensitivity of strain gauges, is 34.0; this value is about 7?15 times higher than the gauge factor of a metal-foil strain gauge. The resistance of the polysilicon strain gauge decreases linearly with an increase in the temperature, and TCR is -328 ppm/℃. Further, nonlinearity and hysteresis are 0.21 % FS and 0.17 % FS, respectively.

Micro Shear-Stress Sensor for Separation Detection During Flight of Unmanned Aerial Vehicles Using a Strain Gauge

Daeban Seo,Yongdae Kim,Sejin Kwon IEEE 2014 IEEE Sensors Journal Vol. No.

<P>A micro shear-stress sensor (MiSS) for real-time detection of flow separation in unmanned aerial vehicles was presented. The direct method was selected for the MiSS, and movement of its floating element was measured using a simple and highly reliable piezoresistive scheme. To realize the MiSS, a polysilicon strain gauge of the piezoresistor type with a very low temperature coefficient of resistivity (TCR) and high gauge factor was first developed. These two characteristics were adjusted by varying the boron concentration during fabrication. The strain gauge was also designed to evaluate the effect of size (width) on these characteristics. The TCR was almost zero and the gauge factor was 32 at a boron concentration of 1.5×10<SUP>19</SUP> cm<SUP>-3</SUP>. The characteristics were unaffected by its width (in the tens of micrometer range). The MiSS was designed and fabricated using the developed polysilicon strain gauge, and its performance was evaluated using a NACA0012 airfoil section in a wind tunnel. At a 0 <SUP>°</SUP> angle of attack (AOA), the resistance of MiSS increased with the flow. At a 20 <SUP>°</SUP> AOA, the resistance did not change owing to detachment of the flow caused by separation. In the real-time separation detection test, the resistance of MiSS decreased as soon as separation occurred. Hence, the separation detection ability of the developed MiSS using a polysilicon strain gauge was verified.</P>

방사선 치료실의 실내 구조와 산란선 측정에 관한 연구

김민애(Minae Kim),권용대(Yongdae Kwon),제재용(Jaeyong Je) 한국방사선학회 2012 한국방사선학회 논문지 Vol.6 No.3

본 연구는 방사선 치료실 내부에 알루미늄 요철 크기가 다른 구조물을 부착하여 방사선 조사 중 발생되는 산란선량을 알아보고자 한다. 알루미늄 요철구조물을 방사선 치료실 벽면에 부착하고, 방사선 조사 중 발생하는 산란선을 측정 대상으로 하였다. 알루미늄 요철의 크기는 1.5×1.5, 3×3, 5×5 ㎠이고 크기는 가로×세로가 60×60 ㎠ 이다. 산란선 측정을 위한 TLD와 치료실 벽면까지의 거리는 310 ㎝이며 사용된 방사선 에너지는 선형가속기에서 발생되는 6 ㎹, 15 ㎹ 이다. 실험 결과 6 ㎹에서는 조사선량이 100, 300 cGy에서는 알루미늄 요철 구조물을 설치함으로써 산란선이 감소되었으나 200 cGy에서는 5×5 ㎠의 요철구조물에서만 산란선이 감소되었다. 15 ㎹에서는 조사선량이 200, 300 cGy에서는 알루미늄 요철구조물을 설치함으로써 산란선이 감소되었으나 100 cGy에서는 요철구조물에 상관없이 비슷한 결과 값을 나타 내었다. 따라서 실내구조에 부가적으로 알루미늄 요철 구조물을 설치하는 것이 방사선 치료실 벽면에서 발생하는 산란선과 환자의 확률적 영향을 감소시킬 수 있는 방법이라 할 수 있다. This research aims at examining the amount of scattered radiation generated during irradiation by adhering structures with different sizes of aluminum prominence and depression to the inside of a radiotherapy room. The irregular aluminum structures were stuck to the wall of a radiotherapy room, and the scattered radiation generated during irradiation was measured. The sizes of the aluminum prominence and depression were 1.5×1.5, 3×3, and 5×5 ㎠ with the width of 60 ㎝ and the height of 60 ㎝. The distance between TLD and the wall of the radiotherapy room to measure scattered radiation was 310 ㎝, and the used radiation energy was 6 ㎹ and 15 ㎹ generated from a linear accelerator. The research result showed that the irradiation amount at 6 ㎹ was 100, and at 300 cGy the scattered radiation decreased by the installation of the structure with aluminum prominence and depression, but at 200 cGy, only the scattered radiation of the uneven structure of 5×5 ㎠ decreased. At 15 ㎹, the irradiation amount was 200 cGy, and at 300 cGy, the scattered radiation was reduced when the rugged aluminum structure was set up, but at 100 cGy, similar result values were produced regardless of the uneven structure. Consequently, installation of an additional structure with aluminum prominence and depression in the present interior structure can decreased the stochastic effect of the scattered radiation generated from the wall of a radiotherapy room and patients.

수리계획모형을 활용한 대도시 폐기물 관리 시스템의 광역화 운영 계획에 관한 연구

김재희,김승권,이용대 한국경영과학회 2003 經營 科學 Vol.20 No.1

The increased environmental concerns and the emphasis on recycling are gradually shifting the orientation of municipal solid waste (MSW) management. This paper is designed to evaluate regionalization programs for MSW management system. We developed a mixed integer network programming (MIP) model to identify environment- friendly, const-effective expansion plans for regionalization scenarios considered. The MIP model is a dynamic capacity expansion model based on the network flow model that depicts the MSW management cycle. In particular, our model is designed to determine the optimal form of regionalization using binary variables. We apply this model to assess the regionalization program of Seoul Metropolitan City, which includes three scenarios such as 1) districting, 2) regionalization with neighboring self-governing districts, and 3) globalization with all districts. We demonstrate how our model can be used to plan the MSW system. The results indicate that optimal regionalization with nearby self-governing districts can eliminate unnecessary landfills and expansions if jurisdictional obstacles are removed.

Micro Shear-Stress Sensor for Separation Detection During Flight of Unmanned Aerial Vehicles Using a Strain Gauge

Seo, Daeban,Kim, Yongdae,Kwon, Sejin IEEE Sensors Council 2014 IEEE SENSORS JOURNAL Vol.14 No.4

A micro shear-stress sensor (MiSS) for real-time detection of flow separation in unmanned aerial vehicles was presented. The direct method was selected for the MiSS, and movement of its floating element was measured using a simple and highly reliable piezoresistive scheme. To realize the MiSS, a polysilicon strain gauge of the piezoresistor type with a very low temperature coefficient of resistivity (TCR) and high gauge factor was first developed. These two characteristics were adjusted by varying the boron concentration during fabrication. The strain gauge was also designed to evaluate the effect of size (width) on these characteristics. The TCR was almost zero and the gauge factor was 32 at a boron concentration of 1.5 x 10(19) cm(-3). The characteristics were unaffected by its width (in the tens of micrometer range). The MiSS was designed and fabricated using the developed polysilicon strain gauge, and its performance was evaluated using a NACA0012 airfoil section in a wind tunnel. At a 0 degrees angle of attack (AOA), the resistance of MiSS increased with the flow. At a 20 degrees AOA, the resistance did not change owing to detachment of the flow caused by separation. In the real-time separation detection test, the resistance of MiSS decreased as soon as separation occurred. Hence, the separation detection ability of the developed MiSS using a polysilicon strain gauge was verified.

재순환 공간 추가에 의한 다적층 마이크로 혼합기의 효율 향상

이종광(Jongkwang Lee),김용대(Yongdae Kim),권세진(Sejin Kwon) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월

It is so difficult to small amounts of two or more fluid species into single in microchannel because flows are usually laminar. In this regard multilamination micro mixer including recirculation zone is presented. Alternating feed micro channels make multilamination and converging-diverging channels form recirculation zone. Multilamination with geometric focusing decreases diffusion path and recirculation zones make vortex. In this paper flow patterns and mixing properties of multilamination micro mixer including recirculation zone were investigated by Computational Fluid Dynamics (CFD). The CFD results provided qualitative information on mixing.

Structural Insights for β-Lactam Antibiotics

( Dogyeoung Kim ),( Sumin Kim ),( Yongdae Kwon ),( Yeseul Kim ),( Hyunjae Park ),( Kiwoong Kwak ),( Hyeonmin Lee ),( Jung Hun Lee ),( Kyung-min Jang ),( Donghak Kim ),( Sang Hee Lee ),( Lin-woo Kang ) 한국응용약물학회 2023 Biomolecules & Therapeutics(구 응용약물학회지) Vol.31 No.2

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.