• 분석과학
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• 제32권4호
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• pp.131-138
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• 2019

This paper reports results on the physical properties of a powder type of $Al_2O_3:C$ commonly used as a luminescence dosimeter using the LM-OSL technique. On the analysis with the general order kinetics model, the LM-OSL signal measured appeared to be composed of three components (fast, medium, slow) showing the largest area in the medium component. The photoionization cross sections of three components were distributed between $10^{-19}{\sim}10^{-21}cm^2$. The values of the thermal assistance energy were evaluated the largest in slow component and the smallest in fast component, which indicates the electrons trapped in defects attributed to slow component should be the most sensitive to thermal vibration among three components. In illumination to blue light, the fast component showed a rapid linear decay and completely disappeared after light exposure time of about 5 s. The medium component decayed with two exponential elements but the slow component did not observed any noticeable change until light exposure time of 40 s. In a dose response study, all components exhibited a linear behaviour up to approximately 10 Gy.

• KIEAE Journal
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• 제14권4호
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• pp.111-117
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• 2014

In South Korea, the government has recently enforced regulations associated with buildings. Temperature restriction in indoor environment is one of the common ways of energy reduction in order not to dissipate heating and cooling energy; however the people who are in restricted temperature feels uncomfortable. Furthermore, occupants cannot feel the same thermal sensation even they are in the same place. For the reason, occupants should express their thermal sensation and HVAC system should be able to apply their demand. It is proved by an adaptive principle. The adaptive model means that people react in ways which tend to restore their comfort, when change occurs such as to produce discomfort. In order to design HVAC control strategies based on adaptive model, we designated an existing office building as a reference building to gather data from actual field. Furthermore, we gathered occupants' thermal sensation and clothing insulation in real-time. We filtered the data with Kalman's filter method. The data was reasonable when there is an alarm messages for asking questionnaire. The response ratio were different in occupants' thermal condition. In conclusion, the filtered occupants' thermal sensation can be used as a real time HVAC control and input value of HVAC control.

• 분석과학
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• 제31권1호
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• pp.7-13
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• 2018

이 연구에서는 구석기 고토양층 석영의 시간분해 광자극 냉광 신호를 측정한 후 측정된 냉광신호로부터 시료의 냉광수명을 산출하였다. 냉광수명의 방사선 조사 후 열전처리 의존성 및 조사선량 의존성, 광자극 펄스 의존성을 모두 고려한 결과, 고토양층 석영의 시간분해 광자극 냉광은 방사선량 100 Gy 조사 후 별도의 열전처리 없이 펄스 주기 $250{\mu}s$, 펄스 폭 $10{\mu}s$, 반복수 100,000번인 광 자극 펄스를 가하여 측정할 때 정확한 냉광수명이 산출됨을 알 수 있었다. 냉광수명의 측정온도 의존성으로부터 산출된 열소광 활성화 에너지 ${\Delta}E$, thermal assistance 활성화 에너지 $E_a$는 각각 $0.60{\pm}0.14eV$, $0.053{\pm}0.029eV$ 이었으며, 이 결과는 기존에 보고된 연구 성과와 매우 잘 일치하였다. 결론적으로 이 연구에서 산출된 고토양층 석영의 운동학 변수 값은 매우 신뢰할 수 있다고 판단된다.

• KIEAE Journal
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• 제14권3호
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• pp.39-45
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• 2014

Energy poverty has been defined as low-income households who paid energy cost more than 10% of their ordinary income. Therefore, there are various subsidy programs focused on house remodeling for low-income households and one of them is the Home Energy Efficiency Assistance Program which have done by Korea Energy Foundation since 2007. The aim of the program is to improve the thermal performance of dilapidated dwellings and analyzed the detached house for the low-income households to develop the building typology. The database contained approximately 3,061 households which was obtained from the program in 2013 and the results of the study were like this; 1) For the shape of residential houses, the number of rectangular shaped building was higher than non-rectangular shaped ones. 2) For the orientation of buildings, the south layout of the detached housing was dominant to gain heating energy into buildings. 3) For the floor area, the average floor area was $44.2m^2$, although its size varied wide variations, which range from $6.3m^2$ to $107.1m^2$. 4) For the windows and doors, the south-facing window was larger than the other side. Finally it would be possible to determine the characteristics of residential houses for low-income families. A future study could establish typology of low-income housing that it would estimate the performance of each model building before and after the retrofit to improve the energy performance.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1611-1625
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• 2020

We propose a scaled-down experimental model of vertical air-natural convection channels by applying the modified Ishii-Kataoka scaling method with the assistance of numerical analyses to the Reactor Vault Cooling System (RVCS) of the Proto-type Gen-IV Sodium-cooled fast reactor (PGSFR) being developed in Korea. Two major non-dimensional numbers (modified Richardson and Friction number) from the momentum equation and Stanton number from the energy balance equation were identified to design the scaled-down experimental model to assimilate thermal-hydraulic behaviors of the natural convective air-cooling channel of RVCS. The ratios of the design parameters in the PGSFR RVCS between the prototype and the scaled-down model were determined by setting Richardson and Stanton number to be unity. The friction number which cannot be determined by the Ishii-Kataoka method was estimated by numerical analyses using the MARS-KS system code. The numerical analyses showed that the friction number with the form loss coefficient of 2.0 in the scale-down model would result in an acceptable prediction of the thermal-hydraulic behavior in RVCS. We also performed experimental benchmarking using the scaled-down model with the MARS-KS simulations to verify the appropriateness of the scale-down model, which demonstrated that the temperature rises and the average air flow velocity measured in the scale-down model.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1654-1659
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• 2017

The boundary layer of a two-dimensional forced convective flow along a persistent moving horizontal needle in an electrically conducting magnetohydrodynamic dissipative nanofluid was numerically investigated. The energy equation was constructed with Joule heating, viscous dissipation, uneven heat source/sink, and thermal radiation effects. We analyzed the boundary layer behavior of a continuously moving needle in Blasius (moving fluid) and Sakiadis (quiescent fluid) flows. We considered Cu nanoparticles embedded in methanol. The reduced system of governing Partial differential equations (PDEs) was solved by employing the Runge-Kutta-based shooting process. Computational outcomes of the rate of heat transfer and friction factors were tabulated and discussed. Velocity and temperature descriptions were examined with the assistance of graphical illustrations. Increasing the needle size did not have a significant influence on the Blasius flow. The heat transfer rate in the Sakiadis flow was high compared with that in the Blasius flow.

• Geomechanics and Engineering
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• 제16권4호
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• pp.363-373
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• 2018

The evaluation of Thermo-Hydro-Mechanical (THM) coupling behavior is important for the development of underground space for various purposes. For a high-level radioactive waste repository excavated in a deep underground rock mass, the accurate prediction of the complex THM behavior is essential for the long-term safety and stability assessment. In order to develop reliable THM analysis techniques effectively, an international cooperation project, Development of Coupled models and their Validation against Experiments (DECOVALEX), was carried out. In DECOVALEX-2015 Task B2, the in situ THM experiment that was conducted at Horonobe Underground Research Laboratory(URL) by Japan Atomic Energy Agency (JAEA), was modeled by the research teams from the participating countries. In this study, a THM coupling technique that combined TOUGH2 and FLAC3D was developed and applied to the THM analysis for the in situ experiment, in which rock, buffer, backfill, sand, and heater were installed. With the assistance of an artificial neural network, the boundary conditions for the experiment could be adequately implemented in the modeling. The thermal, hydraulic, and mechanical results from the modeling were compared with the measurements from the in situ THM experiment. The predicted buffer temperature from the THM modelling was about $10^{\circ}C$ higher than measurement near by the overpack. At the other locations far from the overpack, modelling predicted slightly lower temperature than measurement. Even though the magnitude of pressure from the modeling was different from the measurements, the general trends of the variation with time were found to be similar.

• 에너지공학
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• 제24권4호
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• pp.192-199
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• 2015

북한은 "자력갱생"의 경제기조 아래, 에너지 수급원을 수력과 화력에 집중해왔으나, 구 공산권의 몰락에 따른 관련 기자재 공급 불안정, 홍수 등 각종재해에 따른 설비 노후화 등에 기인한 극심한 에너지난을 겪으며, 에너지원의 다양화에 대한 관심이 대내외적으로 증대되고 있다. 특히, 신재생에너지는 북한 송전망 상황에 부합하는 분산형 에너지원이라는 점과, 자력갱생 기조에 부합하는 자체 생산 가능한 에너지라는 점에서 대북 에너지지원의 최선책으로 회자되고 있으며, 바이오가스는 식량증산과 연계하여 북한 주민의 인권 향상에 기여할 수 있어, 인도적 지원측면에서 FAO, WFP 등 국제기구를 통한 지원이 원활할 것으로 예상되는 바, 신재생에너지원 중에서도 지원가능성이 가장 높은 에너지원으로 손꼽히고 있다. 그러나 한편으로는 지원 물품의 군사적 용도로의 전용가능성과 전략물자의 유입에 대한 우려 또한 높은 실정이며, 북한의 핵실험 및 미사일 발사 등 군사적 도발에 따른 UN 안전보장이사회결의와 국제사회의 경제제재가 대북 지원의 걸림돌이 되고 있다. 본 논문에서는 바이오가스플랜트의 대북지원 가능 물품에 대하여 UN 제재품목여부를 기반으로 제재가능성을 평가하고, 원활한 대북지원을 위한 해결책을 논하고자 한다.