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정우찬,한봉석,이홍림 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.8
Theoretical equation to calculate thermal fatigue life was derived in which slow crack growth theory was adopted. The equation is function of crack growth exponent n. Cyclic thermal fatigue tests were performed at temperature difference of 175, 187 and 200$^{\circ}C$ respectively. At each temperature difference critical thermal fatigue life cycles of the alumina ceramics were 180,37 and 7 cycles. And theoretical thermal fatigue life cycles were calculated as 172, 35 and 7 cycles at the same temperature difference conditions. Therefore thermal fatigue behavior of alumina ceramics can be represented by derived equation. Also theoretical single cycle critical thermal shock temperature difference can be calculated by this equation and the result was consistent with the experimental result well.
정우찬,한봉석,이홍림,이형직 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.10
The thermal fatigue behavior of alumina ceramics was investigated by water quenching method. Single-quench thermal shock tests were performed to decide the critical thermal shock temperature difference ($\Delta$Tc) which was found to be 225$^{\circ}C$ Cyclic thermal shock fatigue tests were performed at temperature diff-erences of 175$^{\circ}C$, 187$^{\circ}C$ and 200$^{\circ}C$ respectively. After cyclic thermal shock fatigue test the distributions of retained strength and crack were observed. Retained strength was measured by four point bending method and crack observation method bydye penetration. In terms of the retained strength distribution the critical number of thermal shock cycles(Nc) were 7 for $\Delta$T=200$^{\circ}C$, 35 for $\Delta$T=187$^{\circ}C$ and 180for $\Delta$T=175$^{\circ}C$ respec-tively. In terms of the crack observation the critical number of thermal shock cycles were 5 for $\Delta$T==200$^{\circ}C$ 20 for $\Delta$T==187$^{\circ}C$ and 150 for $\Delta$T=175$^{\circ}C$ respectively. The difference of Nc investigated by two different methods is due to the formation of the longitudinal cracks which had no effect on the four point bending strength. Therefore the thermal fatigue behavior of alumina ceramics could be more accurately described by the crack observation method than the retained strength measurement method.
정우찬,문흥만,장민호,이현곤,황명환,우인성 한국가스학회 2019 한국가스학회지 Vol.23 No.6
This study deals with a process for recovering hydrogen isotopes from fusion exhaust gas. The goal of this process is to remove impurities, maximally recover only pure hydrogen isotopes. Experiments using hydrogen and deuterium were conducted to confirm the possibility of the recovery of hydrogen isotopes. In the exhaust gas containing H2, impurities was removed in the membrane process, and only pure H2 was recovered. And the H2 in the exhaust gas of the He-GDC(Glow Discharge Cleaning) process was recovered using a cryogenic adsorption process. In addition, HAZOP analysis was performed for qualitative risk assessment. For scenario analysis, the damage prediction ALOHA program was used to calculate the range of influence. Finally measures were sought to improve safety. 본 연구는 핵융합 배기가스에서 수소동위원소를 회수하기 위한 공정에 관한 것이다. 이 공정은 불순물을 제거하고 수소동위원소만을 최대로 회수하는 것이 목표이다. 수소와 중수소를 이용한 실험을 통해 수소동위원소의 회수가능성을 확인하고자 하였다. 수소가 포함된 배기가스는 주로 분리막 공정에서 불순물을 제거하여 순수한 수소만을 회수하고, 헬륨-글로우 방전 세척 공정의 배기가스는 초저온 흡착 공정을 이용해서 수소를 회수하였다. 또한 정성적 위험성 평가를 위해 HAZOP 분석을 실시하였다. 시나리오 분석을 위해서 피해 예측 ALOHA 프로그램을 사용하여 영향 범위를 산출하고, 안전성 방안을 모색하였다.
핵융합 배가스 중 수소 회수를 위한 촉매반응 특성 연구
정우찬,정필갑,김정원,문흥만 한국수소및신에너지학회 2015 한국수소 및 신에너지학회논문집 Vol.26 No.5
In D-T fusion reaction, D2 (duterium) and T2(tritium) are used as fuel gas. The exhaust gas of nuclear fusion includes hydrogen isotopes Q2 (Q means H, D or T), tritiated components (CQ4 and Q2O), CO, CO2, etc. All of hydrogen isotopes should be recovered before released to the atmosphere. This study focused on the recovery of hydrogen isotopes from CQ4 and Q2O. Two kinds of experiments were conducted to investigate the catalytic reaction characteristics of SMR (Steam Methane Reforming) and WGS (Water Gas Shift) reactions using Pt catalyst. First test was performed to convert CH4 into H2 using 6% CH4, 6% CO / Ar feed gas. In the other test, 100% CO gas was used to convert H2O into H2 at various reaction conditions (reaction temperature, S/C ratio, GHSV). As a result of the first test, CH4 and CO conversion were 41.6%, 57.8% respectively at 600°C, S/C ratio 3, GHSV 2000 hr -1 . And CO conversion was 72% at 400°C, S/C ratio 0.95, GHSV 333 hr -1 in the second test.
밑면격리 하이브리드 제어시스템에 적용된 제어기 축소기법
정우찬,이진호 대한건축학회지회연합회 2007 대한건축학회지회연합회 학술발표대회논문집 Vol.2007 No.1
The purpose of this study is to verify an applicability of Balanced Model Reduction(BMR) technique known as one of the controller reduction technique, for an active vibration control in a base isolated structure subjected to the seismic excitations. A controller devised in a reduced order can have beneficial effects not only on computing time required for generating the input forces but also on the hardware implementations. The control algorithm used in the closed loop control system in this study is called Loop Transfer Recovery(LTR) method to enhance the robust stability against the uncertainties inherently existing in the mathematical model, resulting in a full order controller. The order of the controller is then reduced by BMR technique as the prescribed procedures. The performance of the reduced controller is determined from the time history responses as well as the frequency responses. The results indicate that the reduced order control system using BMR technique with LTR method(BMR/LTR) exhibits nearly identical responses characteristics to those of the full order control system in both the time and the frequency domain.
Pd 분리막을 이용한 수소동위원소 회수 실험과 공정 시뮬레이션
정우찬,박종환,한상우,장민호,이현곤 한국수소및신에너지학회 2021 한국수소 및 신에너지학회논문집 Vol.32 No.4
Hydrogen isotopes, which are used as raw materials in fusion reaction, participate in the reaction only in small amount, and most of them are released together with impurities. In order to recover and reuse only hydrogen isotopes from this exhaust gas, a recovery process is required, and most of the hydrogen isotopes can be recovered using a Pd Membrane. In this study, the recovery rate of hydrogen isotopes was measured through the first and second stage Pd membrane experiments. In the case of the experiment using a single stage Pd membrane, about 99.2%, and in the case of the first stage and second stage Pd membrane connection experiments, a recovery rate of 99.9% or more was obtained. Therefore, the recovery rate of Pd membrane process applied to hydrogen can be applied to hydrogen isotopes. In addition, the simulation model was established using aspen custom modeler, a commercial software, and the validity of the simulation was checked by applying the references and experimental data. The simulation results based on the experimental data showed a difference of 2% or less.