• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.47-48
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• 2001

본 연구의 목적은 폐 구리염화물 용액을 원료로 사용하여 분무열분해 공정에 의해 평균입도가 1㎛이하이며 입도분포가 균일하고 치밀한 조직을 나타내는 미립의 구리산화물 분말을 제조하는데 있다. 또한 본 연구에서는 분무열분해 공정에 의해 생성되는 분말의 특성에 영향을 미치는 반응 온도, 원료용액의 유입속도, 분위기 기체 및 공기의 유입속도, nezzle tip 크기 및 원료용액의 농도 등의 반응인자들의 영향을 검토하였다.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.226-227
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• 2007

유도결합 플라즈마(ICP)에서 안테나의 특정부분에 유도자기장을 보강 또는 상쇄 시키는 형태의 두 안테나를 고안하였다. 플라즈마 밀도와 전자온도, 플라즈마 전위, 전자에너지 분포함수 등의 플라즈마 파라미터들로 그 특성을 비교하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.60.1-60.1
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• 2011

비정질 indium-gallium-zinc-oxide (a-IGZO)는 thin film transistor (TFT)에 적용되는 대표적인 active layer로써 높은 이동도를 갖고, 도핑 농도의 제어가 용이하며 낮은 온도에서도 대면적에 증착할 수 있는 특성을 가지고 있다. 특히 저온에서 대면적 증착이 가능한 장점을 갖고 있어 LCD 분야뿐만 아니라 다양한 분야에서 상용화하려는 연구가 시도되고 있다. a-IGZO를 구성하는 물질 중에 이동도에 중요한 역할을 미치는 In은 대표적인 투명전극물질인 indium-tin oxide (ITO)에서 고전류 구동에 의한 확산이 널리 알려져 이에 대한 증명과 개선을 위한 연구가 진행되고 있다. 보고된 결과에 따르면 device에 지속적인 구동 전압을 가했을 때 In이 유기층로 확산되어 organic light emitting diode(OLED)의 성능을 저하시키는 것으로 알려져 있다. 따라서, a-IGZO에서도 고전류 구동에 의한 indium의 이동이 필수불가결하다고 판단된다. 본 연구에서는 a-IGZO TFT에 고전압 구동을 반복적으로 시행함으로써 발생하는 전기적 특성의 변화를 확인하였고, 동일한 소자의 전극과 채널 사이의 계면에서 In 분포를 energy dispersive spectrometer (EDS)로 관찰하여 In 분포와 전기적 특성 간의 상관관계에 대해 연구하였다.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.89-94
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• 2009

The stack effect in high-rise buildings is expected more significant at nights in winter due to the large temperature difference between the inside and outside of the buildings. However, the existence of large openings such as natural ventilators on the floor may effect the position of neutral plane, smoke spread at fire and thus obstruct the door openings for rescue. In this paper, the vertical and horizontal pressure distribution with different openings of natural smoke ventilators was experimentally analyzed by investigating pressure differentials.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.625-636
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• 2017

This study looked into the behavior of precast concrete track due to temperature variation and initial track deformation and examined the effect of initial deformation and deformation caused by temperature gradient on the stress distribution of slab under train load. In this paper, one of two papers in a series, a finite element analysis model for calculating deformation and stress of precast concrete track was proposed; the temperature distribution and displacements measured at the precast concrete track in the field were compared with the analytical results. The results show that the slab always curled up due to initial deformation; by comparing the measured displacements with the displacements calculated by taking measured temperatures at each depth as input, the effective built-in temperature (EBITD), the temperature difference between the top and bottom of the slab corresponding to the initial deformation, can be estimated. If EBITD is relevantly assumed, the calculated displacements correlate well with the measured ones.

• Journal of Bio-Environment Control
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• v.21 no.1
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• pp.1-11
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• 2012

The objective of the present study is to provide data needed to find double covering method to be able to improve environment of temperature, humidity and PPF in tomato greenhouse. The distribution charts of temperature, humidity and PPF which were measured in environment control conditions such as thermal insulation, air heating, roof ventilation and air fog cooling in conventional and air inflated double layers greenhouses were drawn and analysed. The thermal insulation effect of the air inflated greenhouse was the same as that of conventional greenhouse because the temperature between insulation curtain and roof covering material was equal in heating season. The ventilation effect of the air inflated greenhouse was superior to the conventional greenhouse. The temperature distribution in the fog cooled greenhouse was uniform and the cooling effect was about $3.5^{\circ}C$. The condensation on the roof covering surface could be controlled by removing the moisture between insulation curtain and roof covering by using humidifier. The PPF of conventional greenhouse was more decreased than the air inflated greenhouse as time went by because the transmittance of conventional greenhouse declined by dust collected on the inside plastic film owing to rolling up and down operation for ventilation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.7
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• pp.567-578
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• 2015

Single droplet-wall collision heat transfer characteristics on a heated plate above Leidenfrost temperature were experimentally investigated considering the effects of impact velocity. The collision characteristics of the droplet impinged on the heated wall and the changes in temperature distribution were simultaneously measured using synchronized high-speed video and infrared cameras. The surface heat flux distribution was obtained by solving the three-dimensional transient heat conduction equation for the heated substrate using the measured surface temperature data as the boundary condition for the collision surface. As the normal impact velocity increased, heat transfer effectiveness increased because of an increase in the maximum spreading diameter and a decrease in the vapor film thickness between the droplet and heated wall. For We < 30, droplets stably rebounded from a heated wall without breakup. However, the droplets broke up into small droplets for We > 30. The tendency of the heat transfer to increase with increasing impact velocity was degraded by the transition from the rebounding region to the breakup region; this was resulted from the reduction in the effective heat transfer area enlargement due to the breakup phenomenon.

• Journal of the Korean GEO-environmental Society
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• v.14 no.7
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• pp.19-29
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• 2013

Analysis via classical soil mechanics theory is either ineffective or inappropriate for fully describing stress distribution or failure conditions in cold regions, since mechanical properties of soils in cold regions are different from those reported in the classical soil mechanics theory. Therefore, collecting and analyzing technical data, and systematic and specialized research for cold regions are required for design and construction of the structure in cold regions. Freezing and thawing repeat in active layer of permafrost region, and a loading condition affecting the structure changes. Therefore, the reliable analysis of mechanical properties of frozen soils according to various conditions is prerequisite for design and construction of the structure in cold regions, since mechanical properties of frozen soils are sensitive to temperature condition, water content, grain size, relative density, and loading rate. In this research, the direct shear apparatus which operates at 30 degrees below zero and large-scaled low temperature chamber are used for evaluating shear strength characteristics of frozen soils. Weathered granite soil is used to analyzed the shear strength characteristics with varying freezing temperature condition, vertical confining pressure, relative density, and water content. This research shows that the shear strength of weathered granite soil is sensitively affected by various conditions such as freezing temperature conditions, normal stresses, relative densities, and water contents.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.636-645
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• 2022

In this study, we investigated the adsorption characteristics of methyl orange (MO), an anionic dye, on ginkgo shell-based activated carbon (AC). For this purpose, ACs (GS-1, GS-2, and GS-4) with different textural properties were prepared using ginkgo shells and potassium hydroxide (KOH), a representative chemical activating agent. The correlation between the textural characteristics of AC prepared and the mixing ratio of KOH was investigated using nitrogen adsorption/desorption isotherms. The MO adsorption equilibrium experiment on the prepared ACs was conducted under different pH (pH 3~11) and temperature (298~318 K) conditions, and the results were investigated by Langmuir, Freundlich, Sips and temperature-dependent Sips equations. The feasibility of the MO adsorption treatment process of the prepared AC was also investigated using the dimensionless Langmuir separation factor. The heterogeneous adsorption properties of MO for the prepared AC examined using the adsorption energy distribution function (AED) were closely related to the system temperature and textural characteristics of AC. The kinetic results of the batch adsorption performed at different temperatures can be satisfactorily explained by the homogeneous surface diffusion model (HSDM), which takes into account the external mass transfer, intraparticle diffusion, and active site adsorption. The relationship between the activation energy value obtained by the Arrhenius plot and the adsorption energy distribution function value was also investigated. In addition, the adsorption process mechanism of MO on the prepared AC was evaluated using Biot number.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4072-4080
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• 2014

The Peltier Module has been used to dissipate the heat from electronic devices and electronic components. In this module, a heat sink is used to release the operating heat into the air outside. This study addressed the heat transfer characteristics for a heat sink with an inner tunnel. Under forced and natural convection conditions, the heat transfer characteristics were different. Therefore, the cooling and heating performances were studied for the heat sink, which has an inner tunnel. The heat transfer conditions were also evaluated by performing an experimental test, which investigated the heat transfer characteristics related to the variance in time and temperature distribution. Experiments on the heat transfer characteristics of the heat sink were conducted based on the forced and natural convection and temperature distribution changes. In the cooling experiment, the A- and B-shaped cooling pin heat sinks decreased the temperature of the forced convection than the temperature of natural convection. In the forced and natural convection, the A- and B-shaped decreased to a minimum of $-15^{\circ}C$. Under the forced and natural convection conditions, A- and B-shaped cooling pin heat sinks decreased the temperature when the voltage was increased. In the heating experiment, the A- and B-shaped cooling pin heat sinks increased the temperature of the forced convection than the temperature of natural convection. In forced convection, when the voltage was $15^{\circ}C$, the temperature of the A-shaped cooling pin heat sink increased to $150^{\circ}C$, and the temperature of the B-shaped cooling pin heat sink increased to $145^{\circ}C$. Under forced and natural convection conditions, the A- and B-shaped cooling pin heat sinks showed an increase in temperature with increasing voltage.