• 한국가스학회지
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• 제14권6호
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• pp.7-14
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• 2010

본 연구에서는 자착화특성이 다른 DME와 n-Butane을 이용하여 다양한 흡기공급방식에 따른 HCCI엔진연소에서 압력상승률의 저감특성에 대하여 조사하였다. 연소실내부의 가스압력측정, 광학측정용 엔진을 이용한 화학발광법의 측정 그리고 화학반응수치계산을 통하여 연소실내부에서 각 국소부분의 연소특성을 파악하였다. 최대압력상승률은 DME와 n-Butane의 혼합 상태에 의해 결정되어진다. DME가 성층화되고 n-Butane이 균일하게 분포되진 조건에서 가장 많이 감소되는데 두 연료가 균일한 경우에 비해서 최대압력상승률은 0.25MPa/ms 로 저감되었고 CA50도 5deg 지각되었다.

• Nuclear Engineering and Technology
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• 제30권5호
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• pp.403-415
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• 1998

The CANDU 6 reactor assembly consists of an array of 380 pressure tubes, which are installed horizontally in a large cylindrical vessel, the Calandria, containing the low pressure heavy water moderator. The pressure tube is located inside the calandria tube and the annulus between these tubes, which forms a closed loop with $CO_2$ gas recirculating, is called the Annulus Gas System(AGS). It is designed to give an alarm to the operator even for a small pressure tube leak by a very sensitive dew point meter so that he can take a preventive action for the pressure tube rupture incident. To judge whether the operator action time is enough or not in the design of Wolsong 2,3 & 4, the Leak Before Break(LBB) assessment is required for the analysis of the pressure tube failure accident. In order to provide the required data for the LBB assessment of Wolsong Units 2, 3, 4, a series of leak detection capability tests was performed by injecting controlled rates of heavy water vapour. The data of increased dew point and rates of rise were measured to determine the alarm set point for the dew point rate of rise of Wolsong Unit 2. It was found that the response of the dew point depends on the moisture injection rate, $CO_2$ gas flow rate and the leak location. The test showed that CANDU 6 AGS can detect the very small leaks less than few g/hr and dew point rate of rise alarm can be the most reliable alarm signal to warn the operator. Considering the present results, the first response time of dew point to the AGS $CO_2$ flow rate is approximated.

• 수산해양기술연구
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• 제28권2호
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• pp.184-190
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• 1992

The combustion characteristics, ignition delay, p-t, dp/dt, Q-t of diesel oil and fish oil blended diesel oils was investigated according to pressure and temperature in a constant volume combustion bomb. The results are as follows: 1) The influence of temperature and pressure on the ignition delay was almost constant in high temperature, regardless of the blending rates, and the ignition delay was shortest in the 60% blend. 2) The maximum pressure was high in order of with pure diesel oil, with the 20% blend and the 60% blend. 3) The rate of pressure rise was high in order of with pure diesel oil, with the 20% blend and the 60% blend. The rate of maximum pressure rise was significantly higher with pure diesel oil than with two blends. 4) The amount of accumulative heat release was large in order of with pure diesel oil, with the 20% blend and the 60% blend.

• 대한치과기공학회지
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• 제35권2호
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• pp.127-136
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• 2013

Purpose: In order to find out the impact of changes in polymerization conditions of orthodontic acrylic resin on maximum load. Methods: While maintaining mixing ratio 3:1 of polymer and monomer in spray-on way in the production condition of polymerization temperature $25^{\circ}C$ or $37^{\circ}C$ for 10 minutes or 30 minutes of polymerization time by pressure $3kfg/cm^2$ or $6kfg/cm^2$ in the lab maintaining $25^{\circ}C$ of room temperature, the change in maximum load rise rate was tested by producing 5 acrylic resin specimens for orthodontics per group to meet the standards of $25mm{\times}2mm{\times}2mm$ and using INSTRON with the 3rd bar 2mm in diameter and parallel support bending device of $15{\pm}0.1mm$ as test equipment showing 30.00mm/min of crosshead speed, $50{\pm}16$ N/min of load ratio in the laboratory of $24^{\circ}C$ room temperature and as a result, the following results were obtained. Results: 1. When increasing pressure from $3kfg/cm^2$ to $6kfg/cm^2$, maximum load was lowered by -4.285%. 2. When increasing polymerization time from 10 minutes to 30 minutes, maximum load rose by 3.848%. 3. When increasing polymerization temperature from $27^{\circ}C$ to $37^{\circ}C$, maximum load rose by 5.854%. Conclusion: Considering the above test results that polymerization time and polymerization temperature when polymerizing acrylic resin for orthodontics according to changes in working conditions had an impact on the rate of rise of maximum load values but the rate of rise was lowered when increasing pressure from $3kfg/cm^2$ to $6kfg/cm^2$, we came to a conclusion that high pressure more than necessary does not affect the rate of rise of maximum load.

• 대한기계학회논문집B
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• 제34권5호
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• pp.449-456
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• 2010

HCCI 엔진은 고효율, 저공해를 실현할 수 있는 차세대 내연기관이다. 그러나 HCCI 엔진이 상용화되기 위해서는 몇 가지 문제점들이 해결되어야 한다. 그 중에서 가장 큰 문제점은 과도한 압력 상승률이 노킹을 발생시키기 때문에 운전영역이 제한되는 것이다. 이번 연구의 목적은 HCCI 엔진에서 압력상승률 저감을 위하여 온도 성층화와 농도 성층화 효과를 조사하는 것이다. 그리고 Multi-zone 모델을 이용한 화학반응 수치해석을 통하여 연소 및 배기가스 특성에 미치는 영향을 알아보았다. 수치해석에서 2 단계 열발생을 가지는 DME와 1단계 열발생을 가지는 메탄을 사용하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.409-414
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• 2009

Since cryogens are stored at very low temperatures, the cryogenic storage systems are quite sensitive to heat leaks. Even though the vessel operated under sealed condition with vacuum insulation and reflective coatings are used, the heat leakage into the vessel is still unavoidable. Therefore, this paper concerns with numerical study of self-pressurization used to analysis the optimum design with the variation volume fraction, effect of heat flux and storage pressure of liquid nitrogen. The result shows that as the volume fraction increases, the pressure rise reduces and the relatively at atmosphere pressure is better than the higher one. In addition, higher heat flux leads the pressure rise increases faster than low one. The additional of heat pipe system to reduce the pressure rise rate also has been done. By this comparison, the optimum design for storage umbilical cord blood can be selected.

• 대한약리학회지
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• 제1권1호
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• pp.53-61
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• 1965

Effects of intraventricular norepinephrine (NE) on rabbit blood pressure and heart rate were investigated. 1) Blood pressure was little affected by small doses of NE (below $500{\mu}g$) but showed marked rise by 1 mg. 2) Heart rate was decreased by intraventriccular NE $(200{\sim}500{\mu}g)$. One mg of NE caused less pronounced bradycardia than with smaller doses. The bradycardia could not be observed in vagotomized or atropinized animals. 3) Intraventricular NE potentiated reflexive bradycardia produced by 5-hydroxytryptamine. 4) Cord-sectioned rabbit showed different responses; the smaller doses $(100{\sim}200{\mu}g)$ produced transitory bradycardia and depression of blood pressure, which followed by tachycardia and pressure rise. The transitory bradycardia and depressor effects were not observed in cord-sectioned and vagotomized rabbit. 5) Treatment of animals with reserpine, guanethidine and hexamethonium changed the effects of intraventricular NE on blood pressure, i.e., in these cases the smaller doses of NE caused maked elevation of blood pressure. 6) From these observations it was inferred that central NE caused stimulation of cardioinhibitory and vasomotor center. The former seemed to be more sensitive to NE than the latter. Susceptibility of the vasomotor center to NE seemed to be influenced by peripheral sympathetic tone.

• 한국환경보건학회지
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• 제32권3호
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• pp.222-226
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• 2006

Smoking of tobacco cigarettes is associated with a rise in blood pressure together with increase in heart rate. This study was aimed to examine the acute effect of tobacco and non-tobacco cigarette smoking on the blood pressure and heart rate by randomized crossover study. In the results, systolic/diastolic blood pressure and heart rate changes after smoking were significantly different between male and female group. Blood pressure and heart rate were elevated after smoking, but statistical significance for the difference was identified only in the female group. Because Non-tobacco smoke made from leaves of E. ulmoides has no nicotine, its effect on blood pressure and heart rate was negligible. Remarkable difference of heart rate changes in women was observed between tobacco cigarette smoking group and non-tobacco cigarette smoking group.

• 한국터널지하공간학회 논문집
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• 제6권1호
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• pp.25-40
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• 2004

밀장전한 암반발파공에서 화약폭발로 전파되는 초음속 충격파는 암반중에 전파되면서 차자로 저음속 충격파, 소성파, 탄성파로 변화된다. 이 연구는 발파압력파의 최대압력 도달시간 산정에 중점을 두었고 연계된 논문 I (the companion paper)에서는 최대 발파업력 산정에 중점을 두었다. 이 연구에서 최대압력 도달시간을 화약밀도, 단열지수, 폭광파속도, 감쇠지수, 동적항복강도, 소성파속도, 암반밀도, 탄성파속도, Hugoniot 상수의 함수식으로 유도하였다 최대합력 도달시간에 대한 매개변수분석 결과 암반특성치가 화약특성치보다 더 크게 영향을 미쳤다. 최대압력 도달시간의 확률분포는 화약과 암반 특성치의 확률분포로부터 Rosenblueth 확률모델로 조합하여 산출되었다. 화약과 암반특성의 불확정성이 발파진동의 불확정성에 미치는 영향을 수치해석으로 분석하였다. 불확정성 분석결괴 화약특성보다 암반특성의 불확정성이 발파진동에 더 크게 영향을 미쳤다. 수치해석 분석결괴 최대 발파양력과 최대양력 도달시간의 바인 하중재하율이 발파진동에 큰 영향을 미쳤다. 또한 화약특성보다 암반특성이 하중재하율에 더 크게 영향을 미쳤다.

• 대한기계학회논문집
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• 제16권1호
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• pp.180-188
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• 1992

본 연구에서는 와류실식 디젤 기관에 경유-물의 유화연료 사용시 시관의 회전 속도(1500rpm)가 일정인 경우 물의 첨가량(체적비, 0~20%)과 기관의 부하(BMEP,2.1~ 7.5kg/$\textrm{cm}^2$)변화에 따른 연소실내 압력, 압력상승률 및 열발생률, 착화지연 기간, 연료 소비율 등의 연소특성과 CO, HC, NOx 및 매연의 배출능도 등 유해 배출 가스에 미치는 영향에 관하여 실험적으로 구한 것이다.