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Sunjin Yim,Sungchul Kim,Inhwan Kim,Jae-Woo Park,Jin-Hyoung Cho,Mihee Hong,Kyung-Hwa Kang,Minji Kim,Su-Jung Kim,Yoon-Ji Kim,Young Ho Kim,Sung-Hoon Lim,Sang Jin Sung,Namkug Kim,Seung-Hak Baek 대한치과교정학회 2022 대한치과교정학회지 Vol.52 No.1
Objective: The purpose of this study was to investigate the accuracy of one-step automated orthodontic diagnosis of skeletodental discrepancies using a convolutional neural network (CNN) and lateral cephalogram images with different qualities from nationwide multi-hospitals. Methods: Among 2,174 lateral cephalograms, 1,993 cephalograms from two hospitals were used for training and internal test sets and 181 cephalograms from eight other hospitals were used for an external test set. They were divided into three classification groups according to anteroposterior skeletal discrepancies (Class I, II, and III), vertical skeletal discrepancies (normodivergent, hypodivergent, and hyperdivergent patterns), and vertical dental discrepancies (normal overbite, deep bite, and open bite) as a gold standard. Pre-trained DenseNet-169 was used as a CNN classifier model. Diagnostic performance was evaluated by receiver operating characteristic (ROC) analysis, t-stochastic neighbor embedding (t-SNE), and gradientweighted class activation mapping (Grad-CAM). Results: In the ROC analysis, the mean area under the curve and the mean accuracy of all classifications were high with both internal and external test sets (all, > 0.89 and > 0.80). In the t-SNE analysis, our model succeeded in creating good separation between three classification groups. Grad-CAM figures showed differences in the location and size of the focus areas between three classification groups in each diagnosis. Conclusions: Since the accuracy of our model was validated with both internal and external test sets, it shows the possible usefulness of a one-step automated orthodontic diagnosis tool using a CNN model. However, it still needs technical improvement in terms of classifying vertical dental discrepancies.
Residual analysis of veterinary drugs in bovine and equine muscle by targeted sampling plan in 2022
Sunjin Park(Sunjin Park),Chung-Oui Hong(Chung-Oui Hong),Se-Hyung Kim(Se-Hyung Kim),Jihye Kim(Jihye Kim),Inhae Jeon(Inhae Jeon),Seon-Young Lee(Seon-Young Lee),Moon Her(Moon Her),Sung-Won Park(Sung-Won 한국예방수의학회 2023 예방수의학회지 Vol.47 No.2
The Animal and Plant Quarantine Agency conducts a targeted sampling plan and analysis for veterinary drugs within the country every year. Target compounds included tetrachlorvinphos as an organophosphate, diminazene as an anti-infective medication, ketoprofen as a nonsteroidal anti-inflammatory drug, triclabendazole and clorsulon as flukicides in 2022. These compounds were not included in National Residues Program (NRP), despite their high sales ranking. A total of 94 bovine muscle samples and 20 equine muscle samples were collected from various locations across the country. The analysis of target compounds in muscle was performed using LC-MS/MS coupled with Food code 8.3.1 revised in 2022. A 2 g sample of muscle tissue was extracted using a water: acetonitrile (1:4, v/v) solution, then cleaned up with C18 and hexane saturated with acetonitrile. Compounds were separated with C18 column and mobile phases consisted of 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B). All analytes exhibited good linearity with correlation coefficients (R2) higher than 0.992. The limit of quantification (LOQ) of these compounds ranged from 0.21 to 2.79 μg/kg except for diminazene (3.85~6.86 μg/kg). The average recoveries of these analytes were 89.45~129.13% in muscle at spiked level of 10 or 20 μg/kg. Relative standard deviations (%) (intra-day and inter-day) were lower than 20% for all target compounds, except for diminazene and triclabendazole, whose intra-day RSD % was slightly higher than 20% in equine muscle. Testing confirmed that all 94 bovine and 20 equine muscle samples from 9 provinces were free from residues of veterinary drugs. Monitoring of compounds not included in the NRP should continue to ensure consumer health and food safety.
Highly Luminescent InP/GaP/ZnSNanocrystals and TheirApplication to White Light-Emitting Diodes
Kim, Sungwoo,Kim, Taehoon,Kang, Meejae,Kwak, SeongKwon,Yoo, Tae Wook,Park, Lee Soon,Yang, Ilseung,Hwang, Sunjin,Lee, Jung Eun,Kim, Seong Keun,Kim, Sang-Wook American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.8
<P>Highly stable and luminescent InP/GaP/ZnS QDs with a maximum quantum yield of 85% were synthesized by in situ method. The GaP shell rendered passivation of the surface and removed the traps. TCSPC data showed an evidence for the GaP shell. InP/GaP/ZnS QDs show better stability than InP/ZnS. We studied the optical properties of white QD-LEDs corresponding to various QD concentrations. Among various concentrations, the white QD-LEDs with 0.5 mL of QDs exhibited a luminous efficiency of 54.71 lm/W, Ra of 80.56, and CCT of 7864 K.</P>
Kim, Sunjin,Cho, Yeonjoo,Kim, Min Soo,Kim, Minsung Elsevier 2018 ENERGY Vol.147 No.-
<P><B>Abstract</B></P> <P>Supercritical carbon dioxide (S-CO<SUB>2</SUB>) power cycle has been under the spotlight for years as one of the promising solutions to resolve the energy and environmental problem. The most of previous studies focused on cycle performances and applicable configuration. In this study, detailed and extensive analysis on the recompression S-CO<SUB>2</SUB> power cycle was carried out to reflect more practical and desirable conditions. This study focused on the optimization of the S-CO<SUB>2</SUB> cycle by evaluation of the irreversibility of the recuperators using the effectiveness analysis and pinch point temperature difference (PPTD) analysis. Split ratio from the main stream to the recompressor and compression ratio were considered as independent parameters. From the simulation, the characteristics and performance of the recompression cycle were discussed. The optimum operating conditions were determined in combinations of PPTDs of the two recuperators. With the performance curves, control strategy of the two independent parameters is ranged for desirable operation of S-CO<SUB>2</SUB> power cycle.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Characteristics of the S-CO<SUB>2</SUB> recompression power cycle are analyzed. </LI> <LI> Effectiveness and pinch point temperature difference analyses for recuperators were applied. </LI> <LI> Cycle efficiency is maximized where entropy generation is minimized. </LI> <LI> Cycle efficiency is adjustable by controlling split ratio and pressure ratio. </LI> </UL> </P>
하이브리드/전기자동차용 영구자석 모터의 열적 모델링과 냉각 시스템 최적 운전 제어에 대한 연구
김선진(Sunjin Kim),김귀택(Gwiteak Kim),정융(Yoong Jung),김민수(Min Soo Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Because of the environmental issues, hybrid/electric vehicles are becoming the focus of the automotive industry and research field. From this trend, permanent magnet (PM) motors are receiving much attention because hybrid/electric vehicles can replace internal combustion engine as a PM motor to generate driving force. Like internal combustion engine, PM motor can produce power and also heat losses during the driving mode. So PM motor need cooling system to maintain the temperature lower than the temperature limit. So minimizing power consumption for the cooling system can directly affect the mileage extension of electric vehicle. So in this paper, optimal operation control of motor cooling system is studied based on the thermal characteristics of PM motor. For the optimizing PM motor cooling system, thermal modeling of PM motor is also conducted. If heat losses and heat transfer characteristics of PM motor are considered, cooling system control can be conducted efficiently. From the saving power of the cooling system, mileage extension of electric vehicle is calculated for the given driving mode. If the algorithm of the cooling system control is applied for another system of electric vehicle like battery or any other electrical component, electric vehicle driving range will be extended or battery size can be minimized.
액체로켓엔진 열유속 측정용 열유속 게이지 설계 및 시험
김민석(Minseok Kim),김태완(Taewoan Kim),유이상(Isang Yu),김완찬(Wanchan Kim),고영성(Youngsung Ko),김선진(Sunjin Kim) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11
본 연구에서는 케로신/액체산소를 추진제로 사용하는 액체로켓엔진 연소실에서의 열유속을 측정하고자 열유속 게이지를 제작하고 시험 평가하였다. 혼합비 2.2의 연소압 9.5 bar 조건에서 연소시험을 수행하여 열유속 게이지로부터 연소실벽면에서의 시간에 따른 온도분포를 측정하였고, 이 온도분포를 바탕으로 적분법 및 Ansys-Fluent를 활용하여 비정상 열유속을 계산하였다. 정상 연소압에서 열유속은 1.8~1.9 ㎿/㎡, 대류열전달계수는 740~760W/㎡K 을 나타내었다. In this study, to measure heat flux of a liquid rocket engine combustion chamber using kerosene/liquid oxygen, a combustion test was performed at mixture ratio 2.2 and chamber pressure 9.5 bar. The temperature distribution was measured by a heat flux gauge installed in the wall of the combustion chamber and the unsteady heat flux was calculated using the integral method and Ansys-Fluent from the temperature information. The heat flux and the heat transfer coefficient was calculated to be 1.8~1.9 ㎿/㎡ and 740~760 W/㎡ K respectively at steady chamber pressure.