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A computational procedure on predicting temperature field in automotive friction clutches
Byungha Lee(이병하) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the design stage of friction clutches of automobiles, knowledge on the thermo-elasticity, especially the precise prediction technique of maximum temperature and stress, a priori is very informative, In this study, an efficient and reliable thermal analysis technique for the mechanical clutches by using computer modeling and numerical method was developed. A commercial software STAR-CD™ was used to find the convective heat-transfer coefficients. MSC/NASTRAN™ was followed to predict the temperature of clutch with utilization of estimated coefficients. Some experiments were also performed with a dynamometer to verify the procedure and calibrate the thermal load. As conclusion, a design procedure, including numerical steps and experimental techniques for calibration, was proposed.
150 kJ Compact Capacitive Pulsed Power System for an Electrothermal Chemical Gun
Byungha Lee,Jin-Sung Kim,Seong-Ho Kim,Young-Hyun Lee,Kyung-Seung Yang 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.6
A 150 kJ compact capacitive pulsed power system (CCPPS) capable of delivering electrical energy into an electrothermal chemical (ETC) gun on a vehicle has been studied. The CCPPS provides pulsed electrical energy into a capillary plasma injector which generates plasma of tens of thousands °K in temperature and has a nonlinear resistance depending on the current. The design requirements of the CCPPS are as follows: the maximum power of 250 MW, the pulse width of about 0.6 ms, the volume of no more than 0.5 cubic meter, the efficiency of energy transfer over 80 % and the repetition rate of 4~5 times per minute. The constructed CCPPS is composed of four 37.5 kJ capacitor bank modules in parallel to make a trapezoid pulse shape and to satisfy the design requirements. Each module is designed to achieve high reliability, safety, efficiency and energy density to endure severe operating conditions. The results of the performance test on the CCPPS using a 120 mm ETC gun are described.
Byungha Lee,Hanju Cha 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.3
In this paper, the charging characteristics of series resonant type high voltage capacitor chargers considering the transformer stray capacitance have been studied. The principles of operation for the four operational modes and the mode changes for the four different switching frequency sections are explained and analyzed in the range of switching frequency below the resonant frequency. It is confirmed that the average charging currents derived from the above analysis results have non-linear characteristics in each of the four modes. The resonant current, resonant voltage, charging current, and charging time of this capacitor charger as variations of the switching frequency, series parallel capacitance ratio (k=Cp/Cs), and output voltage are calculated. From the calculation results, the advantages and disadvantages arising from the parallel connection of this stray capacitance are described. Some methods to minimize charging time of this capacitor charger are suggested. In addition, the results of a comparative test using two transformers whose stray capacitances are different are described. A 1.8 kJ/s prototype capacitor charger is assembled with a TI28335 DSP controller and a 40 kJ, 7 kV capacitor. The analysis results are verified by the experiment.
Operation of a 2.4-MJ Pulsed Power System for Railgun
Byungha Lee,Sanghyuk An,Seong-Ho Kim,Young-Hyun Lee,Kyung-Seung Yang,Yun-Sik Jin,Young-Bae Kim,Jongsoo Kim,Chuhyun Cho,Seok-Han Yoon,In-Su Koo IEEE 2014 IEEE transactions on plasma science Vol.42 No.10
<P>A 2.4-MJ capacitive pulsed power system (PPS) for a railgun was fabricated, installed, and tested. It consists of four independent 600-kJ segments. Each segment contains six 100-kJ capacitor bank modules, a capacitor charger, a circuit for charge and dump, a relay box, and a segment controller. The 100-kJ unit module is composed of a metalized film capacitor, semiconductor switches, and an inductor. It was designed for a safe operation within 10 kV and 75 kA. All the modules in a segment are charged with the same voltage, but the trigger times of each module are individually controllable. With the 2.4-MJ PPS and a medium caliber railgun, discharge experiments in the breech-shorted condition and launch experiments using aluminum armatures were conducted. With the results, we modified the electrical circuit parameters of the PPS from the initial designed values. The circuit simulation using the modified parameters showed good agreement with the experiment data.</P>
에너지저장 커패시터의 최적 충전을 위한 직렬공진형 컨버터의 운용 모드 비교
이병하(Byungha Lee),강태섭(Taesub Kang),차한주(Hanju Cha) 대한전기학회 2012 전기학회논문지 Vol.61 No.3
In this paper, charging modes of series resonant converter for a high voltage energy storage capacitor are compared in terms of charging time, peak resonant current, normalized peak resonant current and voltage in each operation mode. Operating principles of the full bridge series resonant converter with capacitor load are explained and analyzed in discontinuous and continuous operation mode. Based on the analysis and simulation result, 0.6ω<sub>r</sub><ω<sub>s</sub><0.75ω<sub>r</sub> and 1.3ω<sub>r</sub><ω<sub>s</sub><1.4ω<sub>r</sub> are evaluated to the best range of switching frequency for charging of an high voltage energy storage capacitor. 1.8 kJ/s SRC prototype is assembled with TI 28335 DSP controller and 40 kJ, 7 kV energy storage capacitor. Design rules based on the comparative analysis are verified by experiment.
팬데믹으로 인한 의료자원의 소진(消盡)시 치료의 우선순위(Triage)
안병하(Byungha Ahn) 한국비교사법학회 2022 비교사법 Vol.29 No.4
갑작스런 팬데믹으로 전세계가 어려움을 겪고있다. 특히 팬데믹 초기 대응과정에서의 극심한 혼란은 소위 선진국이라고 하는 나라조차도 피할 수 없는 것이었다. 이러한 경험들을 거치며 이번과 같은 예기치 못한 팬데믹 상황에서 필요한 의료자원의 수가 급증하는 환자의 수를 따르지 못할 때 어떠한 환자부터 치료해야 하는지에 관해 관심이 모아지게 되었고, 실제로 유럽의 몇몇 나라들에서는 의사단체 등에서 이와 관련한 지침을 발표하기도 하였다. 하지만 환자의 생명과 직결되는 이러한 선택의 문제는 민간에 맡겨놓을 성질의 것이 아니라 헌법적 가치에 입각하여 규범적으로 정당화되어야 할 문제이다. 이러한 인식을 기초로 하여 트리아지에 관해 고찰해 본 결과 본고에선 다음과 같은 결론에 이르게 되었다. 물론 트리아지 상황이 발생하지 않도록 대비하는 것이 가장 중요한 일임에는 변함이 없다. 1. 사전적 트리아지는 헌법적 가치에 반하지 않지만, 사후적 트리아지는 인간의 존엄에 반하며 예방적 트리아지는 생명권에 반한다. 2. 의학적 적응증(Indikation), 치료에 대한 환자의 동의, 치료의 긴급성은 트리아지의 전제조건이며 이들과 트리아지의 기준은 구별되어야 한다. 3. 허용되는 트리아지의 기준으로는 환자의 회복가능성이 가장 유력한 것이며, 그 외에 아주 예외적으로 환자의 구조자로서의 기능이나 단기체류 외국인인지 여부, 선착순 등이 엄격한 요건 하에 고려될 여지가 있다. 이에 반해 환자의 연령이나 사회적 지위, 트리아지 상황에 대한 책임, 제비뽑기 등은 올바른 기준이 될 수 없다. 4. 현재 국내의 상황과 같이 아직 트리아지에 관한 입법이 없는 상황에서 의사는 ‘정당한 사유’에 기한 진료의 거부, 의무의 충돌과 같은 법리에 의해 민법상 책임을 피할 수 있을 것이라 생각된다. Die ganze Welt leidet unter der plötzlich ausgebrochenen Corona-Pandemie. Sogar in den Industrieländern (Erste Welt Ländern) war zu Beginn der Pandemie eine medizinisch chaotische und angespannte Situation unvermeidlich. Diese Erfahrung brachte die Wichtigkeit der Triage während einer Pandemie ans Licht, sodass sogar ärzteverbände verschiedener Lnder dazu eigene Richtlinien veröffentlichten. Handlungsanweisungen bei Lebensnotstand sind in erster Linie jedoch eine normative Frage, die durch die Gesetzgeber geregelt werden muss. Aufgrund dieser Erkenntnis kommt die vorliegende Arbeit zu den folgenden Ergebnissen. 1. Während die ex-ante-Triage grundsätzlich nicht der Wertordnung der Verfassung widerspricht, sind die sog. präventive sowie ex-post-Triage nicht zulssig. Letzteres entspricht nicht der Würde des Menschen und die präventive Triage verletzt das Lebensrecht der nicht behandelten Patienten. 2. Eine medizinische Indikation, die Einwilligung des Patienten und die Dringlichkeit der Behandlung gehören zu den Voraussetzungen einer Triage, welche von ihren materiellen Kriterien wie der Erfolgsaussicht zu unterscheiden sind. 3. Als zulässiges Kriterium ist vor allem die Erfolgsaussicht zu nennen. Im Ausnahmefall können unter strengen Voraussetzungen folgende Kriterien bercksichtigt werden: ob der Patient für die Rettung anderer unersetzbar ist oder ob der Patient nicht ein Ausländer ist, der keinen Beitrag zur nationalen Gesundheitsversicherung leistet. Jedoch darf es keine Benachteiligung geben bezüglich Alter, sozialen Status oder Verschulden des Patienten. Los ist auch ein ungeeignetes Mittel, weil dadurch das Ziel der Triage nicht erreicht wird. 4. Es gibt noch kein Triage-Gesetz in Korea. In dieser Situation setzt sich der Arzt, der die Triage durchführt, in die straf- und zivilrechtliche Haftungsgefahr. Mit Hilfe der verschiedenen Rechtfertigungsgründe wie Pflichtenkollision oder berechtigten Behandlungsverweigerung kann er aber einer Haftung entgehen.