침전법에 의한 알루미나 분말제조 IV.ZrO₂의 분산에 의한 Al₂O₃/ZrO₂ 복합체의 제조 및 기계적 특성

홍기곤,이홍림,이형직,이호순 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.2

In this study, a precipitation method, one of the most effective liquid phase reaction, was adopted in order to prepare high-tech Al₂O₃/ZrO₂ composite ceramics. Al₂(SO₄)₃·18H₂O, ZrOCl₂·8H₂O and YCl₃·6H₂O were used as starting materials and NH₄OH as a precipitation agent. Fine powders were prepared at optimum calcination condition. Sinterability of each fine powder and the effects of ZrO₂ on the grain size and mechanical properties of Al₂O₃ were investigated. The composition of Al₂O₃/ZrO₂ composites was fixed as Al₂O₃-15v/o ZrO₂(+3m/o Y₂O₃). The effect of MgO on the grain size of Al₂O₃ZrO₂ ceramics was also investigated.

고출력 CW Nd:YAG 레이저를 이용한 인코넬 600의 용접 특성

유영태,신호준,임기건 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.6

The welding characteristics of Inconel 600 Alloy using a continuous wave Nd:YAG laser are experimentally investigated. The major process parameters studied in the present laser welding experiment were the positions of focus, laser power and travel speed of laser beam. We measured the fusion zone size and its shape using an optical microscope for the observation of cross-sectional area. We performed two tests regarding the tension and the micro hardness for welding quality estimation. Then we measured residual stress in welds by electronic speckle pattern interferometry(ESPI). In conclusion, the optimum butt welding process parameters were 0.5mm focus position, 1.6kW laser power, 1m/min travel speed and 5.5ℓ/min assist gas discharge.

편측형 션형유도전동기의 벡터제어 시뮬레이션

정병호(Byung-Ho Chung),임홍우(Hong-Woo Lim),최연옥(Youn-Ok Choi),조금배(Geum-Bae Cho),백형래(Hyung-Lae Baek),오금곤(Geum-Gon Oh) 전력전자학회 2002 전력전자학술대회 논문집 Vol.- No.-

LIM have mall11y different poll1t considering rotary induction motor, that is end effect In this paper described that, end effect, adding to the rotary induction motor They can be designed because of affects magnetizing inductance and series resistance in the d-axis circuit. After LIM modeling, Using<br/> SVPWM, apply to vector control this model. We can verify feasibility of field oriented control technology can control speed by simulation

FIRE PROPAGATION EQUATION FOR THE EXPLICIT IDENTIFICATION OF FIRE SCENARIOS IN A FIRE PSA

HO-GON LIM,SANG-HOON HAN,JOO HYUN MOON 한국원자력학회 2011 Nuclear Engineering and Technology Vol.43 No.3

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: (1) there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and (2) there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a 2x3 rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification.

Development of a swing check valve model for a low velocity pipe flow prediction

Lim, Ho-Gon,Park, Jin-Hee,Jang, Seung-Cheol Elsevier 2006 Nuclear engineering and design Vol.236 No.10

<P><B>Abstract</B></P><P>A swing check valve is commonly used to prevent a reverse flow in the pipe lines of a nuclear power plant. The flow resistance by the swing check valve varies with the location of the swing disk in the velocity range lower than the required minimum velocity for a full opening of the swing disk, thereby the fluid flow is significantly affected by the dynamic motion of the swing disk. Such a phenomenon is very important to analyze safety issues, one of which is the gravity feed following a loss of the residual heat removal (RHR) which occurs during a mid-loop operation. This paper focused on the development of a new check valve model to enhance the capability of the thermal-hydraulic system code. A new angular momentum equation for the disk of a swing check valve is proposed. The proposed model is implemented into the MARS code and verified through a comparison of the simulation results with the experimental data. In particular, the results of the simulation for the gravity feed line are comparably consistent with the real test data performed in a nuclear power plant.</P>

MOSAIQUE – A network based software for probabilistic uncertainty analysis of computerized simulation models

Lim, Ho-Gon,Han, Sang-Hoon,Jeong, Jae Jun Elsevier 2011 Nuclear engineering and design Vol.241 No.5

<P><B>Research highlights</B></P><P>► We developed network-based software for uncertainty analysis named as MOSAIQUE. ► MOSAIQUE can automatically generate sample input of a computer simulation code. ► Massive sampling calculations can efficiently be performed by network computing. ► MOSAIQUE also provides post-processing function for the simulation results.</P> <P><B>Abstract</B></P><P>Uncertainty and/or sensitivity analyzes are widely used in safety analysis using a computational code. When performing uncertainty analysis, massive time and resources are needed to satisfy the requirements of sampling of the statistical parameters or even distributions of the key parameters. MOSAIQUE (Module for SAmpling Input and QUantifying Estimator) was developed to facilitate the uncertainty analysis using a simulation code. The major functions of MOSAIQUE are (1) to sampling parameter based on its distribution information and generating sampling inputs, (2) to control the calculations using multiple PCs, and (3) to process the calculation results for the generation of information for key parameters. MOSAIQUE was applied for the simple uncertainty calculation, in which tedious time consuming processes could be sufficiently automated including large time reduction by using network computing.</P>

The Effect of an Aggressive Cool-Down Following A Refueling Outage Accident in which a Pressurizer Safety valve is Stuck Open

Lim, Ho- Gon,Park, Jin-Hee,Jang, Seung-Cheol Korean Nuclear Society 2004 Nuclear Engineering and Technology Vol.36 No.6

A PSV (pressurizer safety valve) popping test carried out in the early phases of a refueling outage may trigger a test-induced LOCA(loss of coolant accident) if a PSV fails to fully close and is stuck in a partially open position. According to a KSNP (Korea standard nuclear power plant) low power and shutdown PSA (probabilistic safety assessment), the failure of a high pressure safety injection (HPSI) accompanied by the failure of a PSV to fully close was identified as a dominant accident sequence with a significant impact on low power and shutdown risks (LPSR). In this study, we aim to investigate and verify a new means for mitigating this type of accident using a thermal-hydraulic analysis. In particular, we explore the applicability of an aggressive cool-down combined with operator actions. The results of the various sensitivity studies performed there will help reduce LPSR and improve Refueling outage safety.

FIRE PROPAGATION EQUATION FOR THE EXPLICIT IDENTIFICATION OF FIRE SCENARIOS IN A FIRE PSA

Lim, Ho-Gon,Han, Sang-Hoon,Moon, Joo-Hyun Korean Nuclear Society 2011 Nuclear Engineering and Technology Vol.43 No.3

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: (1) there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and (2) there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a $2{\times}3$ rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification.

저전력 블루투스 비콘 기반 스마트 도어락 시스템 설계

임형곤(Hyung Gon Lim),김혁진(Hyeok Jin Kim),이나영(Na Young Lee),이경호(Ho Kyung Ho),박미화(Mee Hwa park) 한국정보과학회 2017 한국정보과학회 학술발표논문집 Vol.2017 No.12

회전 관성을 고려한 전달행렬법 기반의 Expansion Joint 진동해석

신동호(Shin, Dong-Ho),김상호(Kim, Sang-Ho),윤형호(Yoon, Hyung-Ho),임희곤(Lim, Hee-Gon),오재응(Oh, Jae-Eung),이정윤(Lee, Jung-Youn) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.7

Simplified formulae for axial and bending natural frequencies of a bellows are developed using an equivalent thin-walled pipe model. The axial and bending stiffness of bellows is determined using lumped transfer matrix method. Transfer matrix method which includes the rotary inertia is used to calculate the natural frequencies for axial and lateral vibration. The result from the simplified formula are verified by those from as experiment result and a finite element analysis. This comparisons show good agreement with the each other.