http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Kim, Myungjoon,Lim, Gi-Taek,Kim, Yong-Jin,Han, Bangwoo,Woo, Chang Gyu,Kim, Hak-Joon Elsevier 2018 Journal of aerosol science Vol.117 No.-
<P>We developed and investigated the air cleaning performance of a novel electrostatic precipitator (ESP)-type small air purifier with a carbon brush ionizer and an activated carbon fiber (ACF) filter. This version had a high particle charging rate and a low ozone emission rate. Applying a negative voltage of 10 kV to the carbon brush ionizer increased the single-pass particle collection efficiency of 0.3-mu m particles from 17.8% to 47.1%. The flow rate was maintained at 362 L/min, and the efficiency increased to 64.2% as we applied a negative voltage to the collection stage and increased the voltage to 10 kV. This was relatively low when compared to a market-leading commercial HEPA filter-type small air purifier (80.7%). However, our novel purifier showed a particle clean air delivery rate (CADR) of 0.31 m(3)/min, approximately a 1.7 times higher than that for the commercial purifier (0.18 m(3)/min) due to its high flow rate and low pressure drop. We measured the gas removal efficiency in a 1-m(3) test chamber with acetic acid, acetaldehyde, and ammonia; after 30 min of operation, the results were 97.9%, 92.4%, and 87.8% for the novel purifier and 95.2%, 65.4%, and 57.9% for the commercial purifier, respectively. The ozone concentration was measured in a closed test chamber (30.4 m(3)) over 15 h of continuous operation, and it showed a maximum value of 2.5 ppb, much lower than the current standard for ESPs (50 ppb).</P>
Numerical study on heat transfer and pressure drop in laminar-flow multistage mini-channel heat sink
Kim, Yeongseok,Kim, Myungjoon,Ahn, Chisung,Kim, Hyeong U.,Kang, Sang-Woo,Kim, Taesung Elsevier 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.108 No.1
<P><B>Abstract</B></P> <P>Mini-channel has been more studied recently than micro-channel to optimize the heat emission and pressure drop by regulating the channel size and length. In this work, a multistage mini-channel heat sink using water coolant was designed to obtain a larger cooling rate in a small area with a lower pressure drop. To confirm the performance of the structure, we conducted numerical simulations under laminar and single-phase conditions. The diameter and length of the channel were 2 and 530mm, respectively. From the simulation, the local convection coefficient, coolant temperature, channel-wall temperature, effectiveness, and pressure drop were analyzed in relation to the mass flux, heat-source temperature, and number of stage stacks. To obtain valid simulation results on the heat transfer, we used well-matched conventional correlation. The result of the pressure drop was compared with the experimental result to confirm the validity of the hydrodynamic model. The simulation result shows that the maximum cooling rate was 40W/cm<SUP>2</SUP> at a pressure drop of 1383Pa in a quintuple-stage model. However, the triple-stage structure had the best effectiveness of 0.83 under the same simulation conditions. The pressure drop of the multistage structure was higher than that of the single-stage structure. However, the increase of the total pressure drop was small as against the increase of the cooling rate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A multistage mini-channel heat sink is proposed to increase the cooling rate. </LI> <LI> Numerical simulations were done to verify the multistage mini-channel performance. </LI> <LI> The optimum structure is the triple stage that yields the largest heat emission among the multistage mini-channel. </LI> <LI> Multistage structure could improve the cooling rate with the small increase of the pressure drop. </LI> </UL> </P>
A Study on the VR Goggle-based Vision System for Robotic Surgery
Young Gyun Kim,Gyeongbin Mun,Byoungjun Jeon,Jong Hyeon Lee,Dan Yoon,Byeong Soo Kim,Myungjoon Kim,Seong-Ho Kong,Kyu Eun Lee,Chang Wook Jeong,Minwoo Cho,Sungwan Kim 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9
Robot-assisted surgery (RAS) using the da Vinci surgical system (dVSS) has been widely performed owing to its high-definition stereoscopic visualization and improved maneuverability, which has been developed from minimally invasive surgery. However, there was motivation to resolve the chronic fatigue suffered by surgeons because of stereo viewer, the vision system of the dVSS. Reflecting the clinical opinions, a virtual reality (VR) goggle was proposed to enhance the convenience by replacing the stereo viewer, and its applicability was investigated. Based on the da Vinci research kit, validation of the VR goggle was performed by analyzing the condition of its use and implementing the performance assessment. In addition, user evaluations, such as performance analysis, questionnaire surveys, and ergonomic analysis, were conducted to determine the difference in the performance and satisfaction between the stereo viewer and VR goggle. Following the IRB approval, a retrospective analysis of the results was performed. Based on the comparison between the vision systems, the VR goggle was evaluated positively by the surgeons and novices. Satisfaction with the ergonomic properties of the VR goggle averaged 3.9 on a five-point Likert scale, and there was no significant difference in the performance when using the VR goggle and stereo viewer in both groups. Adopting the VR goggle, the volume of the vision system could be decreased by 87.6%. Considering that the VR goggle was better than the stereo viewer in terms of satisfaction and ergonomic analysis with analogous performance, it has the main contribution that the VR goggle can be a promising candidate. as a new vision baseline to research the enhancements of the RAS platform in further studies.
김명준 ( Myungjoon Kim ),강새하늘 ( Saehaneul Kang ),남한 ( Han Nam ) 한국심리유형학회 2021 심리유형과 인간발달 Vol.22 No.2
본 연구는 MBTI에 관심을 지닌 연구자들 및 MBTI 사용자들을 위하여 이들 두 채점체계의 특징을 비교·소개하고자 하는 목적으로 수행되었다. MBTI Form M은 두 가지 채점 방식을 가지고 있다. 즉 문항반응이론(IRT)에 기반한 컴퓨터 채점과 단일 배점 방식에 기반한 자가채점 방식이다. 구체적 연구내용으로 첫째, 자가채점 방식의 일반적 특징과 선호문자 산출 과정을 기술하고 해당 방식으로 산출한 문항의 양호도와 검사의 신뢰도를 확인하였다. 둘째, 컴퓨터채점 방식의 일반적 특징과 선호문자 산출 과정을 기술하고 해당 방식으로 산출한 문항의 양호도와 검사의 신뢰도를 확인하였다. 특히 MBTI 사용자 및 연구자에게 생소할 수 있는 문항반응이론을 컴퓨터채점 방식에 적용하고 해석하는 방법을 자세히 기술하였다. 셋째, 두 채점체계로 산출한 선호문자의 일치율을 계산하여 지표별 선호를 구분하는 가장 정확한 중간점을 기술하였다. 이와 같은 연구를 위하여 2012년부터 2020년까지 어세스타에 누적된 자료 중 대한민국 인구 분포와 맞게 비례층화 방식으로 표집한 19,070명을 분석에 사용하였다. 주요연구 결과는 다음과 같다. 첫째, 문항의 양호도를 나타내는 자가채점 방식의 선호문자 예언율이 E, I, S, T, J 문자에서 Form G와 비교해 개선된 것으로 나타났으며, 4개 지표의 문항내적합치도 또한 .90 수준으로 나타났다. 둘째, 문항반응이론으로 산출한 3모수를 통해 문항의 양호도를 확인한 결과 변별도 기준으로는 E-I 지표가, 난이도 기준으로는 E-I, S-N 지표가, 추측도 기준으로는 E-I, T-F 지표가 매우 좋은 수준으로 나타났다. 추가로 문항반응이론에서 신뢰도를 의미하는 검사정보함수를 그래프로 산출한 결과 선호도 추정치인 세타(θ)의 중간점 부근에서 가장 많은 정보를 포함하여 선호도가 뚜렷하지 않은 사람들의 유형을 정확히 분류해주는 것으로 나타났다. 셋째, 자가채점과 컴퓨터채점의 선호문자를 비교한 선호지표별 일치율은 96.3%~98.1%로 나타났으며, 자가채점 지표별 문항의 절반을 기준으로 선호지표를 결정할 때 일치율이 가장 높았다. 마지막으로 두 채점절차의 차이로 인해 발생하는 선호문자의 불일치는 대부분 중간범위에서 발생되는 것을 확인하였다. 끝으로 본 연구의 의의와 후속연구 제언을 구분하여 논의하였다. There are two scoring methods in MBTI Form M. One is Item Response Theory (IRT)-based computer scoring method, and the other one is unit-weight based self-scoring method. This study introduces and compares the unique characteristics of those two different scoring methods and summarizes the findings for MBTI users and researchers. In this study, there are three main contributions. First, authors addressed the aspects of self-scoring method and the process of obtaining preference types, and then examined the quality of items. Additionally, the overall reliability of assessment was described. Second, the characteristics of computer scoring method and the process of obtaining preference type were discussed, and the item’s quality and reliability of the assessment were examined. In particular, authors elaborated the details of IRT application to MBTI scoring for audiences, including MBTI users and researchers. Lastly, the preference types’ concordance rate from the two scoring methods was calculated to see the most accurate middle point, which identifies the preference indicator. In total, 19,070 samples were used in this study. The samples were collected from Assesta’s server that contained archived data from 2012 to 2020, and proportional stratified sampling method was used to obtain the final samples. There are three main findings in this study. First, the predictive rate was advanced from E, I, S, T, and J indicators. The predictive rate of preference type (self-scoring method) is an indicator of item’s quality, which was improved in comparison with the same rate from Form G. Additionally, internal consistency of four indicators were found to be .90 or above. Second, each item’s quality was examined by using three parameters from IRT model. Specifically, in terms of the good item indices, item discrimination index was good in E-I indicator, item difficulty index was good in E-I and S-N indicators, and item guessing index was good in E-I and T-F indicators. In addition, test information function, which is the indicator of reliability in IRT, was computed with a graph. The result showed that the majority of information was found near the middle point of theta (θ; preference estimate), which helps in identifying people who do not have a clear preference. Third, the preference type’s concordance rate was 96.3~98.1%, which was compared with the preference results from the computer and self-scoring methods, and the concordance rate was highest when people decided their preference types in the middle of self-scoring items. Lastly, the inconsistencies of preference types due to the differences of two scoring methods was mostly found in the middle range. At the end, the implications of this study and the future research directions were discussed.
Park, Myungjoon,Park, Junsik,Choi, Joungcheul,Kim, Jinwoo,Jeong, Seonghoon,Seung, Manho,Lee, Seokkiu,Kim, Jingook [Institute of Electrical and Electronics Engineers 2019 IEEE transactions on electromagnetic compatibility Vol.61 No.1
<P>Voltage noise and operation errors in an integrated circuit (IC) due to electrostatic discharge (ESD) events were measured, validated, and analyzed in this paper. A simplified structure of a laptop personal computer and an IC with a D-type flip-flop were designed and manufactured for the experimental tests. Every signal input to the IC was simultaneously measured during the ESD tests, and validated with the simulated results using a full-wave solver and a simple circuit model. Next, SPICE simulations were conducted using the measured voltages with ESD tests. The output waveforms and the statistical occurrence ratios of the operation failures found from the SPICE simulations were compared with measured values. Furthermore, the effects of decoupling capacitors on the IC operation failures due to ESD were investigated.</P>