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유성목,박준호,박종태,유종근,Yu, Seong-Mok,Park, Joon-Ho,Park, Jong-Tae,Yu, Chong-Gun 한국전기전자학회 2011 전기전자학회논문지 Vol.15 No.2
본 논문에서는 3중 모드 고효율 DC-DC 벅 변환기를 설계하였다. 설계된 벅 변환기는 부하 전류가 큰 경우(100mA~500mA)에는 PWM(Pulse Width Modulation) 제어 방식을 사용하고, 부하 전류가 작은 경우(1mA~100mA)에는 PFM(Pulse Frequency Modulation) 제어 방식을 사용하며, 부하 전류가 1mA 이하인 대기모드(sleep mode)에서는 LDO(Low Drop Out)를 사용한다. 또한, PFM 모드에서 부하 전류가 작은 경우 효율을 증가시키기 위해 DPSS(Dynamic Partial Shutdown Strategy) 기법을 사용하였다. 그 결과 설계된 변환기는 넓은 부하 전류 범위에서 높은 효율을 얻을 수 있다. 제안된 벅 변환기는 CMOS 0.18um공정을 이용하여 설계되었다. 최대 효율은 96.4% 이고, 최대 부하 전류는 500mA이다. 입력과 출력 전압은 각각 3.3V와 2.5V이며, 칩 크기는 PAD를 포함하여 1.15mm ${\times}$ 1.10mm이다. This paper describes a tripple-mode high-efficiency DC-DC buck converter. The DC-DC buck converter operate in PWM(Pulse Width Modulation) mode at moderate to heavy loads(100mA~500mA), in PFM(Pulse Frequency Modulation)at light loads(1mA~100mA), and in LDO(Low Drop Out) mode at the sleep mode(<1mA). In PFM mode DPSS(Dynamic Partial Shutdown Strategy) is also employed to increase the efficiency at light loads. The triple-mode converter can thus achieve high efficiencies over wide load current range. The proposed DC-DC converter is designed in a CMOS 0.18um technology. It has a maximum power efficiency of 96.4% and maximum output current of 500mA. The input and output voltages are 3.3V and 2.5V, respectively. The chip size is 1.15mm ${\times}$ 1.10mm including pads.
유성목(Seong-Mok Yu),박준호(Joon-Ho Park),박종태(Jong-Tae Park),유종근(Jong-Gun Yu) 대한전기학회 2010 정보 및 제어 심포지엄 논문집 Vol.2010 No.10
This paper describes a low-voltage high-efficiency DC-DC buck converter. The proposed DC-DC buck converter operate in PWM(Pulse Width Modulation) mode at moderate to heavy loads(100㎃~500㎃), in PFM(Pulse Frequency Modulation)at light loads(1㎃~100㎃), and in LDO(Low Drop Out) mode at the sleep mode(<1㎃) The triple-mode converter can thus achieve high efficiencies over wide load current range. The designed DC-DC converter is fabricated in a CMOS 0.18㎛ technology. It has a maximum power efficiency of 96.4% and maximum output current of 500㎃. The chip size is 1.15㎜ × 1.10㎜ including pads.
저압 인버터용 Busbar 재질 변화에 따른 열유동-전자계 연성해석
정원목(W.M.. Jeoung),목진성(J.S. Mock),김선영(S.Y. Kim),홍찬욱(C.O. Hong),김정빈(J.B. Kim),김경서(K.S. Kim),유성열(S.R. Ryoo) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
The Busbar is generally fabricated by molding a number of copper plates, that is used for electric system such as low voltage inverter and converter. It is conducted a study on replacing as other low-cost materials because of upsurge in raw materials for industry. In previous studies, numerical approaches were investigated to predict the effect of the temperature distribution of replacing to this busbar from copper to aluminum. In this study, thermal-fluid-electromagnetic coupled numerical analyses are performed to take into account the Joule heat effect on the numerical evaluation of the busbar material characteristics. Comparisons with experimental results show that the proposed coupled analysis provides more reliable results than the conventional analyses in predicting the temperature characteristics.
1.5 MVA SYSTEM 고압 인버터의 열유동 해석과 실험을 통한 정합성 검증 평가
목진성(C.S. Mock),유성열(S.R. Ryoo),김선영(S.Y. Kim),안상국(S.K. Ann),전재현(J.H. Jun),홍찬욱(C.O. Hong),나승호(S.H. Na),김경서(K.S. Kim) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
As the demand for saving energies has been getting higher all over the world the development for high-voltage and high capacity inverters has been achieved to reduce energy by controling the consumption patterns of industrial electric equipments. H-Bridge Multi-Level high-voltage inverter being researched is the single phase H-Bridge inverter by using low-voltage power semiconductor devices. It can make high-voltages close to a sine wave by connecting composed cells on series. This is a topology without filters because of the low input and output harmonic, and usages of it have been expanded in metal, oil, natural gas and electricity generation industries. The optimal operation conditions on these kinds of high-voltage inverters are varied by running environment conditions, and the performance tests for thermal stability of inner electric semiconductors changes are partially impossible because of facilities. In this research, the junction temperature of power electronics devices, distribution of surface temperature on heat sink and inner temperature and velocity of cells and systems have been drawn as the results by using ANSYS ICEPAK specialized in CFD simulation of power electronics equipments to secure the thermal reliability of cells and systems for 1500kW high-voltage inverters. Through these outcomes the ventilation structures and an effective arrangement of heat components of cell-based inverters could be applied to the plan for a uniform flow distribution of a high-voltage inverter system. Moreover, the consistency of thermal-flow simulation was proven by comparison of actual temperature through the cell-based performance tests.
유성열(Seong-Ryoul Ryoo),목진성(Chin-Sung Mock),조태식(Tae-Sik Cho),김철주(Chul-Ju Kim) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
The present study deals with the results of a thermo-fluid analysis applied to the cooling plate of the water cooling system developed for IGBT stacks which was designed to keep the power semi-conductors from over heating problems. The cooling plate is to absorb a maximum quantity of 10kW from 4 IGBTs which are to be placed on both sides of the cooling plate 2 IGBTs of them on each surface. For the analysis Adina of CFD Program was used and an analysis was conducted to obtain the knowledges on heat and mass flow at both the plate and fluid flow inside. For the simulation the operational conditions of a temperature difference of 15℃ for the working fluid and a uniform heat flux of about 92000 W/m2 on the surface in contact with an IGBTs.
수술 후 재발한 유두상 갑상선 암의 경부 재발 위험인자에 대한 연구
하태권,유성목,김상효,Tae Kwun Ha,M.D.,Sung Mock Ryu,M.D. and Sang Hyo Kim,M.D. 대한갑상선-내분비외과학회 2010 The Koreran journal of Endocrine Surgery Vol.10 No.4
Purpose: Papillary thyroid carcinoma (PTC) is known to have a favorable prognosis and long-term survival due to its biologic characteristics of slow growth and late distant metastasis. However, its characteristic of lymph node metastasis has resulted in a high incidence of neck recurrence and only rare lung metastasis. The objective of this study is to analyze the characteristics of recurrent or persistent thyroid cancer and to evaluate the risk factors for the development of recurrence. Methods: We retrospectively reviewed 479 consecutive cases of PTC and these patients had undergone surgical operations from January 2004 to December 2006. We assessed age, gender, the tumor characteristics, the operative methods and the recurrence patterns, and the correlations between these factors and recurrence were analyzed. Results: Of the 479 patients with PTC and who were initially treated with surgery at our hospital, 42 patients (8.8%) had recurrent disease. Univariate analysis showed that an age less than 45 years, male gender, extra-thyroidal extension, lymph node metastasis, multifocality, bilaterality and neck node dissection were related to a higher rate of recurrence. Of these, lymph node metastasis and central or lateral neck node dissection were the independent risk factors for recurrent PTC on the multivariate analysis. Conclusion: The significant factors influencing locoregional recurrence and distant metastasis were cervical lymph node metastasis and incomplete neck node dissection. In order to reduce the rate of recurrence of PTC, an exact preoperative evaluation of the nodal status and formal neck node dissection are recommended during the initial surgery in patients who have these factors of recurrence. (Korean J Endocrine Surg 2010;10:261-265)