• 천문학회보
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• 제35권1호
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• pp.71.2-71.2
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• 2010

Cooling hot gas sets a floor on the ionization level for diffuse gas in the ISM in general and the galactic halo. Many high galactic latitude sight lines, cooling hot gas is the dominant source of the ionization. Such sites are prime regions for the formation of both C IV and Si IV ions at a temperature of T~105K. To study of the ISM that have the 104.5~6K ionization state by ionization or photoionization by the collision, searching for the radiation energy that is emitted at far ultra violet range is required. In this paper, we report the analysis of NGP( North Galactic Pole, $l:270^{\circ},b:90^{\circ},rad:40^{\circ}$) region by fuv($1350{\sim}1750{\AA}$) data that are surveyed with FIMS. After making the FIMS FUV image of the NGP region, we divided up into 50 small regions for that and got the spectrum emission lines from each one.

• 천문학회보
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• 제35권2호
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• pp.70.2-70.2
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• 2010

Cooling hot gas sets a floor on the ionization level for diffuse gas in the ISM in general and the galactic halo. Many high galactic latitude sight lines, cooling hot gas is the dominant source of the ionization. Such sites are prime regions for the formation of both C IV and Si IV ions at a temperature of T~105K. To study of the ISM that have the 104.5~6K ionization state by ionization or photoionization by the collision, searching for the radiation energy that is emitted at far ultra violet range is required. In this paper, we report the analysis of NGP(North Galactic Pole, $l:0^{\circ},b:90^{\circ}$,rad: $40^{\circ}$) region by fuv($1350\sim1750\AA$) data that are surveyed with FIMS. After making the FIMS FUV image of the NGP region, we divided up into some small regions for that and got the spectrum emission lines from each one.

• 대한기계학회논문집
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• 제18권5호
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• pp.1218-1226
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• 1994

The shock tube is a useful device for investigating shock phenomena, spray combustion, unsteady gas dynamics, etc. Therefore, it is necessary to analyze exactly the flow phenomena in shock tube. In this study, the mechanics of its reflected shock zone has been investigated by using of the one-dimensional gas dynamic theory in order to estimate the transition from initial reflection of shock wave region. Calulation for four kinds of reflected shock tube temperature (i.e. (a) 1388 K (b) 1276 K (c) 1168 K (d) 1073 K) corresponding to the experimental conditions have been carried out sumarized as follows. (1) The qualitative tendency is almost the same as in that conditions in region of reflected wave region. (2) High temperature period (reflected shock wave temperature) $T_{5}$, exists 0-2.65 ms. (3) Transition period from temperature of reflection shock wave is far longer than the calculated one. This principally attributed to the fact that the contact surface is accelerated, also, due to the release of energy by viscoity effect. This apparatus can advance the ignition process of a spray in a ideal condition that involved neither atomization nor turbulent mixing process, where, using a shock tube, a column of droplets freely from atomizer was ignited behind a reflected shock.

• 천문학회보
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• 제41권2호
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• pp.39.2-40
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• 2016

The molecular gas surrounding an H II region is thought to be a place where star formation can be induced. Such triggered star formation can arise form the overpressurization of existing density enhancements or thought the collapse of a swept up layers of material. In this talk, We will discuss the results of a study of star-formation activity associated with the outer Galaxy ring-shaped H II regions KR 7, KR 81, KR 120 and KR 140 using archival Spitzer and WISE data along with the JHK observations. We used CO data cubes from the FCRAO and TRAO in order to define extent of the molecular cloud associated each HII region. Using the infrared data sets, We identified and classified YSO populations within each molecular cloud using measures such as the class I/II ratio and YSO spatial density. Along with this, one of the main question in the study of star formation is how protostar accrete material from their parent molecular clouds and observations of infall motions are needed to provide direct evidence for accretion. Combining our observation of the YSO population distribution with time scales associated with YSO evolution and HII expansion, we investigated the possible significance of triggered star formation in the molecular cloud surrounding each region.

• 한국분무공학회지
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• 제26권4호
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• pp.171-181
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• 2021

This study presents a prediction methodology of thermodynamic properties by using RK-PR Equation of State in a wide range of temperature and pressure conditions including both sub-critical and super-critical regions, in order to obtain thermophysical properties for hydrocarbon aviation fuels and their products resulting from endothermic reactions. The density and the constant pressure specific heat are predicted in the temperature range from 300 to 1000 K and the pressure from 0.1 to 5.0 MPa, which includes all of the liquid and gas phases and the super-critical region of three representative hydrocarbon fuels, and then compared with those data obtained from the NIST database. Results show that the averaged relative deviations of both predicted density and constant pressure specific heat are below 5% in the specified temperature and pressure conditions, and the major sources of the errors are observed near the saturation line and the critical point of each fuel.

• 대한기계학회논문집B
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• 제34권6호
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• pp.569-577
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• 2010

다상 유체 시스템에 적용할 수 있는 다중스케일 입자 시뮬레이션 기법을 개발하였다. 거시 모델과 미시모델이 만나는 경계영역에서 세가지로 구별되는 기능을 수행하도록 하였다. 먼저, 기상과 액상을 분리하여 연결하기 위해 벽을 설정하였다. 또 경계영역을 근처에서 경계의 위치를 측정하고 이것에 벽의 각도와 위치가 연동하여 접촉각 값을 미시모델에서 거시모델로 전달하게 하였다. 마지막으로, 입자의 삽입과 제거를 통해 경계영역의 질량과 온도를 거시적 조건에 맞추도록 하였다. 이 알고리즘들을 적용한 완전습윤과 부분습윤시스템들은 좋은 결합 결과를 보였다.

• Journal of Advanced Marine Engineering and Technology
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• 제36권2호
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• pp.238-243
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• 2012

저탄소 친환경 대체 에너지의 한 분야인 수소에너지는 화석연료의 개질 및 물의 전기분해 등 다양한 방법을 통해 얻어진다. 수소를 연료로 사용하는 연료전지인 PEMFC용 1kW급 평판형 수소생산시스템을 자체 개발 중이다. 연소조건에 따른 평판형 수소생산시스템의 개질적정온도까지의 승온시간과 CO, $O_2$, $CO_2$의 평균 농도를 통해 개질기 내 연소기의 특성을 조사하여 개질기의 적정 운전조건을 확인하였다. 차후 PEMFC용 고효율 평판형 수소생산시스템의 개발에 있어 수치해석, 수소수율 및 시스템의 전체 효율을 연구하기 위해 기초연구를 진행하였다.

• 한국환경보건학회지
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• 제21권4호
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• pp.1-9
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• 1995

This study was carried to investigate the biodegradability of phenol in the wastewater with the two sludge blanket-packed bed reactor in series. Each reactor had a dimension of 0.09 m i.d. and 1.5 m height and consisted of two regions. The lower region was a sludge blanket of 0.5 m height and the upper region was a packed-bed of 1 m height. The packed bed region was charged with ceramic raschig rings of 10 mm i.d., 15 mm o.d. and 20 mm length. The reactors were operated at 35$\circ$C and the hydraulic retention time(HRT) was maintained 24 hours. The synthetic wastewater composed of glucose and phenol as major components was fed into the reactor in a continuous mode with incereasing phenol concentration. In addition, the nutrient trace metals($Na^+, Mg^{2+}, Ca^{2+}, PO_4^{3-}, NH_4^+, Co^{2+}, Fe^{2+}$ etc.) were added for growing anaerobes. The phenol concentration of the effluent, the overall gas production, the composition of product gas, the efficiency of COD reduction and the duration of acclimation period were measured to determine the performance of the anaerobic wastewater treatment system as the phenol concentration of the influent was increased from 600 to 2400 mg//l. Successfully stable biodegradation of phenol could be achieved with the anaerobic treatment system from 600 to 1, 800 mg/l of the influent phenol concentration. The upper level of influent phenol loading was high enough to meet most of the practical requirement. The duration of acclimation increased with the phenol loading. At steady state of the influent phenol concentration of 1800 mg/l, the treatment performance indicated the phenol reduction efficiency of 99%, the COD reduction efficiency of 99% and the gas production rate of 37 l/day. At the influent phenol concentration of 2400 mg/l, however, the operation of the treatment system was noted unstable. While the concentration of methane in biogas decreased with increasing the influent phenol loading, the carbon dioxide was increased. However, the concentration of hydrogen was varied negligibly. The concentration of methane was high enough to be used as a fuel. As a result, it is suggested that anaerobic phenol wastewater treament was economical in the sense of energy recovery and wastewater treatment.

• 천문학회지
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• 제34권4호
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• pp.285-287
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• 2001

We have studied the nonlinear evolution of a magnetized disk of isothermal gas, which is sustained by its self-gravity. Our objective is to investigate how the Jeans, Parker, and convective instabilities compete with each other in structuring/de-structuring large scale condensations in such disk. The Poisson equation for the self-gravity has been solved with a fourth-order accurate Fourier method along with the Green function, and the MHD part has been handled by an isothermal TVD code. When large wavelength perturbations are applied, the combined action of the Jeans and Parker instabilities suppresses the development of the convection and forms a dense core of prolate shape in the mid-plane. Peripheral structures around it are filamentary. The low density filaments connect the dense core to the diffuse upper region. On the other hand, when small wavelength perturbations are applied, the disk develops into an equilibrium state which is reminiscent of the Mouschovias's 2-D non-linear equilibrium of the classical Parker instability under an externally given gravity.

• Current Photovoltaic Research
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• 제7권1호
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• pp.15-20
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• 2019

Most high-efficiency n-type silicon solar cells are based on the high quality surface passivation and ohmic contact between the emitter and the metal. Currently, various metalization methods such as screen printing using metal paste and physical vapor deposition are being used in forming electrodes of n-type silicon solar cell. In this paper, we analyzed the degradation factors induced by the front electrode formation process using e-beam evaporation of double passivation structure of p-type emitter and $Al_2O_3/SiN_x$ for high efficiency solar cell using n-type bulk silicon. In order to confirm the cause of the degradation, the passivation characteristics of each electrode region were determined through a quasi-steady-state photo-conductance (QSSPC).