• Title/Summary/Keyword: 공저온도

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The Analysis of Geothermal Gradient at Icheon Hot Spa Area (이천 온천원보호지구의 지온경사 해석)

  • Lee, Chol-Woo;Moon, Sang-Ho
    • The Journal of Engineering Geology
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    • v.18 no.2
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    • pp.185-190
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    • 2008
  • Nine wells have been developed for uses of thermal waters at the Icheon hot spa area. Drilling depths of those hot spring wells range from 166 to 294 m and their piezometric heads are located at about 50 m below the surface. Using the differences between the surface and bottom temperatures within all boreholes, we can simply estimate geothermal gradient in this area. Thus, we obtained the highest, lowest and average gradient values as $64^{\circ}C/km$ from SB-2 well, $45^{\circ}C/km$ from SB-1 well and approximately $54.28^{\circ}C/km$, respectively. However, observing the MRD-2 well additionally drilled into the depth of 996 m, we found out that this study area has widely experienced the temperature disturbance due to thermal groundwater penetration through the fracture systems within the depth of 720 m. Unlikely this phenomenon, we can conclude that the groundwater flow below the depth of 720 m does not exist. Therefore, using only those temperature data below the 720 m depth, we can estimate reasonable geo-thermal gradient values as $33^{\circ}C/km$ in this study area. Pumping test shows that outflowing temperature is $36^{\circ}C$ corresponding to the temperature logging data at 720 m depth.

Temperature Log in Boreholes (착정공 온도검층의 이용)

  • 염병우;김형찬
    • Journal of the Korean Society of Groundwater Environment
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    • v.4 no.2
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    • pp.73-77
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    • 1997
  • Temperature log is an effective method for evaluating the thermal situation and ground water flow path within boreholes. When pumping is proceeding, the continuous temperature logs in a neighboring holt are very helpful to assess connectivity between holes. Mean geothermal gradient is calculated as 26.6$^{\circ}C$/km from 400 bottom hole temperatures, their depths, and the annual mean temperature at each location. Various examples of temperature logs in crystalline rocks are described: first examples show linear increases in homogeneous granitic rocks. Another one illustrates that isolated aquifers have connected each other after a borehole is completed. Slopes of temperature gradient indicate ground water inlet and/or outflow within a borehole. The other log concludes that thermal response in observation borehole induced by pumping is related to the location of interconnected fractures.

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Thermoelectric properties of hot pressed polycrystalline $Bi_2Te_3-Bi_2Se_3$ (가압소결된 다결정 $Bi_2Te_3-Bi_2Se_3$ 열전재료의 열전특성)

  • Hwang, C.W.;Hong, I.G.;Paik, D.K.;Choi, S.C.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.4 no.4
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    • pp.363-369
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    • 1994
  • Bimuth telluride base thermoelectrics are prepared by AC current applied hot pressing method. It is possible to minimize the defects arising from the vaporization of Te, thanks to the very short processing time compared to the single crystal growing method. The optimum conditions for the AC applied hot pressing of 95 mol% $Bi_2Te_3-5 mol% Bi_2Se_3$ thermoelectrics are sintering at $400^{\circ}C$, for 2 minutes, under 1500 kgf/$\textrm{cm}^2$, with the particle size of $125 to 250 {\mu}m$, range of powder. The resultant Z value (figure of merit) was $2.2{\times}10^{-3}/K$.

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Cross Flow Filtration of Pichia stipitis by a Hollow Fiber Membrane (Hollow Fiber 막에 의한 Pichia stipitis의 Cross Flow여과)

  • Kim, H.;Chung, I. S.
    • KSBB Journal
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    • v.4 no.1
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    • pp.57-61
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    • 1989
  • The feasibility of separating Pichia stipitis from a fermentation broth using a hollow fiber membrane was evaluated. The permeate flux was affected by such parameters as cell concentration, pH, content of antifoam agents, suction pressure, and recirculation rate. A minor effect of temperature on the flux loss was also observed. A microcomputer-aided backflush was proven effective in alleviating membrane fouling and allowing long term separation of P. stipitis from a fermentation broth.

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A Study on the fabrication parameters in melt spinning and stretching process (용융방사 및 연신공저의 제조변수 연구)

  • 유종범;김진호;김성수
    • Proceedings of the Membrane Society of Korea Conference
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    • 1998.10a
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    • pp.109-111
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    • 1998
  • TIPS 공정에 의한 고분자막 제조기술은 기존의 적정용매가 없어서 분리막 소재로 상용할 수 없었던 결정성 고분자 및 고강도 엔지니어링 플라스틱 등에 대하여 소재의 폭을 넓힐 수 있고 적정 희석제와의 혼합으로 고분자 소재의 용융점을 강화 시킬 수 있어 가공온도의 제약을 어느정도 해결할 수 있다는 장점을 가지고 있다. 또한 TIPS 공정에 의해 제조되는 고분자 matrix, 혹은 고분자 막의 미세구조는 선택된 고분자와 희석제의 종류 및 상분리 mechanism에 따라 크게 달라지므로 이들 제조 변수의 적절한 조절을 할 수 있다. 본 연구에서는 열유도 상분리 공정과 연신공정을 통해 몇가지 제조변수를 조절하여 미세다공성 중공사막을 제조하였다. 고분자-희석제 용융액의 melt viscosity를 변화시켜 보았고, 희석제의 추출 후 열처리를 하여 이에 따른 영향을 알아보았다. 상분리 속도가 막의 구조 및 성능에 미치는 영향을 알아보기 위해 coagulation bath temperature를 변화시켜 보았으며, 몇가지 종류의 coagulant를 사용하여 막을 제조한 후 성능을 측정해 보았다. 또한 기존의 상업용 막과 성능 및 구조를 비교하여 보았다.

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Plasma Effects on Nucleation of the RPCVD/MOCVD Copper Films

  • 이종현;이정환;손승현;박병남;배성찬;최시영
    • Proceedings of the Korean Vacuum Society Conference
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    • 2000.02a
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    • pp.132-132
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    • 2000
  • Cu는 Al에 비하여 낮은 저항(1.8 $\mu$$\Omega$-cm)과 높은 EM 저항성을 가지고 있어 미래의 고속 ULSI 배선물질로 그 중요성이 더욱 증가되고 있으며, 현재까지 많은 연구가 진행되고 있다. 따라서, 본 논문에서는 이러한 방법들을 고려하여 CVD Cu의 문제점인 낮은 성장률의 개선과 Cu 박막의 특성을 향상하고자 수소 플라즈마 공정을 이용하여 plasma 전처리가 초기 Cu 핵생성에 미치는 영향에 대하여 연구하였다. 본 실험에 사용된 장비는 Cu RPCVD/MOCVD이다. 초기 Cu 핵의 생성에 있어서의 수소 플라즈마의 효과를 조사하기 위하여 다음과 같은 3가지의 방법으로 행하였다. 첫 번째는 Cu 박막 형성에서 플라즈마를 사용하지 않은 방법, 두 번째는 플라즈마 전처리공정을 행한 뒤, Cu 박막 증착시 플라즈마는 사용하지 않은 방법, 세 번재는 플라즈마 전처리공저을 행한 뒤 Cu 증착시에도 플라즈마를 사용한 방법이다. 이 세가지 방법의 핵생성 차이를 분석하기 위해서 각각 10초, 20초, 40초 증착시킨 후 grain의 크기와 개수를 비교하였다. 또한 플라즈마의 power에 따른 Cu 핵생성율도 조사하였다. 수소 전처리동안 working pressure는 10분 동안 1 torr로 유지되었으며 substrate의 온도는 20$0^{\circ}C$, r.f.power는 100watt로 설정하였다. Cu RPCVD의 증착조건은 r.f.power는 10watt, substrate의 온도는 20$0^{\circ}C$, gas pressure는 1 torr, Ar carrier gas는 50sccm, hydrogen processing gas는 100sccm, bubbler 온도는 4$0^{\circ}C$, gas line의 온돈느 6$0^{\circ}C$, shower head의 온도는 $65^{\circ}C$로 설정하였다. 증착된 Cu 박막은 SEM, XRD, AFM를 통해 제작된 박막의 특성을 비교.분석하였다. 초기 plasma 처리를 한 경우에는 그림 1에서와 같이 현저히 증가한 초기 구리 입자들이 관측되었으며, 이는 도상 표면에 활성화된 catalytic site의 증가에 기인한다고 보여진다. 이러한 특성은 Cu films의 성장률을 향상시키고, 또한 voids를 줄여 전기적 성질 및 surface morphology를 향상시키는 것으로 나타났다.

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Numerical Analysis of Phase Behavior and Flow Properties in an Injection Tubing during Gas Phase CO2 Injection : Application of Demonstration-scale Offshore CO2 Storage Project in the Pohang Basin, Korea (기체상태의 CO2 주입시 주입관내 상변화 및 유동 특성의 수치해석적 연구 : 포항분지 해상 중소규모 CO2 지중저장 사업에 적용)

  • Jung, Woodong;Sung, Wonmo;Han, Jeong-Min;Song, Youngsoo;Wang, Jihoon
    • Journal of the Korean Institute of Gas
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    • v.25 no.4
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    • pp.10-18
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    • 2021
  • CO2 storage technology in an aquifer is one of the most effective way to decrease global warming due to a high storage capacity and economics. A demonstration-scale offshore CO2 storage project was performed in a geological deep aquifer in the Pohang Basin, Korea for a technological development of large-scale CO2 storage. A challenging issue in the early design stage of the project was to establish the proper injectivity during CO2 injection. To solve this issue, injection conditions were calculated by calculating injection rate, pressure, temperature, CO2 phase change, and thermodynamic properties. For this study, we simulated and numerically analyzed CO2 phase change from gas to supercritical phase and flow behavior in transport piping and injection tubing using OLGA program. Our results provide the injectivity conditions of CO2 injection system combined with a bottomhole pressure of an aquifer.

Numerical Analysis of Flow Characteristics in an Injection Tubing during Supercritical CO2 Injection: Application of Demonstration-scale CO2 Storage Project in the Pohang Basin, Korea (초임계 상태의 CO2 주입시 주입관내 유동 특성의 수치해석적 연구: 포항분지 중소규모 CO2 지중저장 실증 사업에 적용)

  • Jung, Woodong;Sung, Wonmo;Han, Jeongmin;Song, Youngsoo;Wang, Jihoon
    • Journal of the Korean Institute of Gas
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    • v.26 no.4
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    • pp.9-17
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    • 2022
  • This paper is the continuation of our previous paper, which we refer to as numerical analysis of phase behavior and flow properties in an injection tubing during gas phase CO2 injection. Our study in this paper show the results during supercritcal CO2 injection under the same project. Geological CO2 storage technology is one of the most effective method to decrease climate change due to high injectivity and storage capacity and economics. A demonstration-scale CO2 storage project was performed in a deep aquifer in the Pohang basin, Korea for a technological development in a large-scale CO2 storage project. A problem to consider in the early stage design of the project was to analyze CO2 phase change and flow characteristics during CO2 injection. To solve this problem, injection conditions were decided by calculating injection rate, pressure, temperature, and thermodynamic properties. For this research, we simulated and numerically analyzed CO2 phase change from liquid to supercritical phase and flow characteristics in injection tubing using OLGA program. Our results provide discharge pressure and temperature conditions of CO2 injection combined with a pressure of an aquifer.