• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.3
• /
• pp.60-66
• /
• 2006

Notable are the burning rate characteristics of solid propellant burning at extremely high pressure(10000-20000 psia). The burning rate test using closed bomb shows the discontinuous increment around 4000 psia so that the exponent of burning rate(n) is almost double, from 0.4 to 0.8. The pressure-increasing rate of the test motor is about 300 times as high as that of the motor operating at the conventional pressure, less than 2000 psia, is, therefor the burning rate is augmented about 5-50 times. The performance prediction reflecting the pressure-change-rate effect are fairly comparable with the test data at various test conditions.

• Journal of Korean Electronics
• /
• v.2 no.1
• /
• pp.24-30
• /
• 1982

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.2
• /
• pp.215-222
• /
• 1986

This paper presents the results of investigation, the aim of which was to predict theoretically the processes of thermodynamic cycle of M-combustion chamber type diesel engine. The combustion characteristics in cylinder are evaluated from the energy equation for an thermodynamic system in engine cylinder. In order to predict the combustion pressure in cylinder, the engine is divided in various control volumes. The simulation results of combustion characteristics show that the comparison of computed and measured values brings about the good coincidence.

• Korean Journal of Materials Research
• /
• v.10 no.6
• /
• pp.392-397
• /
• 2000

The effect of pressure on the phase transformation in Fe-30Ni-0.35C Alloy and pure metals was investigated by using PDSC(pressure differential scanning calorimeter). As the pressure increased from 1 atm to 60 atm, the $A_s$points of the ausformed martensite and the marformed martensite in Fe-30Ni-0.35C Alloy were lowered about $2~4^{\circ}C$ at reverse transformation. This is why the volume change came down at phase transition(from martensite to autenite). As the pressure increased from 1 atm to 60 atm, $A_f$ points were constant or slightly increased. This is due to the promotion of carbide precipitation with increasing pressure. The enthalpy change of the ausformed martensite in Fe-30Ni-0.35C Alloy was increased by 10~14J/g. The melting points of the pure metals, Se, Sn, Pb, Zn and Te were slightly increased with increasing pressure. The enthalpy changes of the pure metals at melting were little changed or slightly increased with increasing pressure.

• Korean Journal of Food Science and Technology
• /
• v.23 no.5
• /
• pp.605-609
• /
• 1991

The physical properties which must be considered as engineering factors affecting on the evaporation process of fruit juices are boiling point rise, density, viscosity, thermal conductivity and specific heat. These factors are varied with food ingredients, soluble solids, pressure and temperature. In the reserch, it has been worked to obtain the data and to develop prediction model for the boiling point rise as a faction of soluble solid and pressure by the regression of SPSS package program. For the prediction model of density, it was developed as a fuction of soluble solid content on apple and pear juices. For the viscosity model, it was establised by the factors of temperature and content of soluble solid through the optimization program.

• Tuberculosis and Respiratory Diseases
• /
• v.48 no.5
• /
• pp.766-772
• /
• 2000

Background : Pressure rise time (PRT) is the time in which the ventilator aclieves the set airway pressure in pressure-targeted modes, such as pressure control ventilation (PCV). With varying PRT, in principle, the peak inspiratory flow rate of the ventilator also varies. And if PRT is set to a shorter duration, the effective duration of target pressure level would be prolonged, which in turn would increase inspiratory tidal volume(Vti) and mean airway pressure (Pmean). We also postulated that the increase in Vti with shortening of PRT may relate inversely to the patients' basal airway resistance. Methods : In 13 paralyzed patients on PCV (pressure control 18$\pm$9.5 cm $H_2O$ $FIO_2\;0.6\pm0.3$, PEEP 5$\pm$3 cm $H_2O$, f 20/min, I : E1 : 2) with Servo 300 (Siemens-Elema, Solna, Sweden) from various causes of respiratory failure, PRT of 10 %, 5 % and 0 % were randomly applied. At 30 min of each PRT trial, peak inspiratory flow (PIF, L/sec), Vti (ml), Pmean (cm $H_2O$) and ABGA were determined. Results : At PRT 10%, 5%, and 0%, PIF were 0.69$\pm$0.13, 0.77$\pm$0.19, 0.83$\pm$0.22, respectively (p<0.001). Vti were 425$\pm$94, 439$\pm$101, 456$\pm$106, respectively (p<0.001), and Pmean were 11.2$\pm$3.7, 12.0$\pm$3.7, 12.5$\pm$3.8, respectively (p<0.001). pH were 7.40$\pm$0.08, 7.40$\pm$0.92, 7.41$\pm$0.96, respectively (p=0.00) ; $PaCO_2$ (mm Hg) were 47.4$\pm$15.8, 47.2 $\pm$15.7, 44.6$\pm$16.2, respectively (p=0.004) ; $PAO_2-PaO_2$ (mm Hg) were 220$\pm$98, 224$\pm$95, 227$\pm$94, respectively (p=0.004) ; and $V_n/V_T$ as determined by ($PaCO_2-P_E-CO_2$)/$PaCO_2$ were 0.67$\pm$0.07, 0.67$\pm$0.08, 0.66$\pm$0.08, respectively (p=0.007). The correlation between airway resistance and change of Vti from PRT 10% to 0% were r= -0.243 (p=0.498). Conclusion : Shortening of pressure rise timee during PCV was associated with increased tidal volume, increased mean airway pressure and lower $PaCO_2$.

• Journal of the Korean Chemical Society
• /
• v.27 no.2
• /
• pp.102-110
• /
• 1983

The effect of pressure and temperature on the stabilities of the benzene-iodine charge transfer complex have been investigated through ultraviolet spectrophotometric measurements in n-hexane. The stabilities of the complexes were measured at temperatures of 25, 40 and $60^{\circ}C$ up to 1600 bars. The equilibrium constant of the complex formation was increased with pressure and decreased with temperature raising. The absorption coefficient was increased with both pressure and temperature. Changes of volume, enthalpy, free energy and entropy for the formation of complexes were obtained from the equilibrium constants. The red-shift at a higher pressure, the blue-shift at a higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions.

• KDI Journal of Economic Policy
• /
• v.15 no.3
• /
• pp.37-52
• /
• 1993

우리나라에서는 70년대 중반 여후 공공요금관리(公共料金管理)가 물가정책의 주요수단으로 인식되어 왔으나, 다른 나라의 경험을 살펴보면 물가상승압력(物價上昇壓力)의 근본적인 해소가 전제되지 않는 가격규제정책(價格規制政策)은 유효한 물가대책(物價對策)이 아니라는 것이 보편적으로 인정되고 있다. 본고(本稿)의 분석(分析)에 의하면, 공공요금(公共料金)의 변동과 기타물가지수(소비자물가지수에서 공공요금 및 농축수산물지수를 제외한 것)의 변동간에는 장기적으로 같이 움직이는 공적분관계(共積分關係)가 존재한다. 그러나 일반의 인식과는 달리 공공요금의 변동이 기지물가변동(其地物價變動)을 초래하는 것이 아니라, 기타물가상승(其他物價上昇)이 공공요금상승을 유발하였던 것으로 나타났다. 이는 과거의 공공요금관리정책(公共料金管理政策)이 물가대책으로서의 유효성은 높지 않았음을 의미한다. 따라서 향후의 물가안정(物價安定)은 공공요금 등에 대한 직접적인 가격억제(價格抑制)보다는 경제전체의 물가상승압력(物價上昇壓力)을 완화시킬 수 있는 안정위주의 거시정책기조(巨視政策基調)를 통하여 이뤄 나가야 할 것이다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05a
• /
• pp.532-537
• /
• 1996

영광 1호기의 일차계통인 원자로 냉각재 평균온도( $T_{avg}$)를 적정값으로 미세조정하여 운전할 때, 2차계통 주요 운전변수인 주증기압력이 상승하고 터빈출력이 상승함을 발견하여 이에 대한 터빈사이클 열성능 변화를 발전소 전체 열평형 계산에 의해 정량적으로 파악하고, 그 원인을 열역학 2법칙에서의 엔트로피개념을 이용한 유용에너지의 최대값인 엑서지이론을 적용하여 분석하고자하였다. 분석 결과 열평형 계산에서는 전체 열량의 대부분인 63.2%가 복수기에서 손실되는 것으로 나타나는 반면, 열역학 제2법칙의 엑서지를 이용한 분석에서는 비가역손실이 주로 터빈(전체 엑서지의 12.7%)에서 일어나고 그 다음이 복수기(5.7%), 급수가열기(2.1%) 그리고 1,2단 재열기 (1.0%)의 순으로 전체 사이클에서 일어나며, 주증기 압력이 상승할 때 터빈 출력이 상승하는 주원인은 주증기의 유용성(엑서지)이 크게 증가하는 것에 비해 터빈사이클에서의 비가역손실은 적게 증가하기 때문으로 나타났다.다.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.17 no.4
• /
• pp.365-370
• /
• 1988

한외여과법을 이용한 식품 페액의 단백질 분리, 회수에 관한 조작조건의 최적화를 위하여 cheese whey의 투과유속에 대한 세정효과의 영향과 조작압과 한계유속의 상관관계를 측정하여 다음의 결과를 얻었다. 세정의 효과로부터 유지 전용세제를 사용한 경우가 막의 투과유속의 회복율이 가장 높았으므로 whey중에 소량 함유되어 있는 유지분이 막의 투과유속의 저하에 큰 영향을 미침을 알 수 있었고, cheese whey를 한외여과법에 의하여 농축, 분리하는 경우 사용압력범위 $1{\sim}10kg/cm^2$에서 분획분자량 100,000인 막을 사용하는 경우 조작압력 약 $7kg/cm^2$에서 한계유속에 달하였으며, 그 이상으로는 압력을 가하여도 투과유속은 상승하지 않았다. 또한 이력현상의존재도 고려하여 볼 때 과도한 압력은 한외여과의 경우 투과유속의 상승에 효과가 없음을 알 수 있었다.