• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.223-230
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• 2014

This study examined emission characteristics of far-infrared ray, formaldehyde, volatile organic compounds and deodorization rate of particleboard prepared at different target board densities and resin content levels, using the xylem part of Broussonetia Kazinoki Sieb. The deodorization rate increased, as the target density of board and resin content increased. Emission rates of the far-infrared ray and total volatile organic compounds (TVOCs) were 0.892~0.899, and $0.074mg/m^2{\cdot}h$ for particleboard prepared with the resin content of 13% and target density of $0.6g/cm^3$ while the deodorization rate was 80~90% for the same particleboard. The formaldehyde emission factor ranged from $0.004mg/m^2{\cdot}h$ to $0.006mg/m^2{\cdot}h$ for all particleboard fabricated at different resin content and target densities. These results indicate that particleboard prepared from the xylem part of Broussonetia Kazinoki Sieb have a potential as a building construction material.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.231-237
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• 2009

This study presents a numerical model to simulate density currents developing two dimensionally. The ${\kappa}-{\varepsilon}$ model is used for the turbulence closure. Elliptic flow equations are solved by the finite volume method. In order to investigate the applicability of the numerical model, discontinuous density currents are simulated numerically. The vortices due to the instability at the interface are simulated, showing a good agreement with the experimental visualizations in the literature. It is also investigated that the transition from slumping phase to inertial phase occurs when a bore generated at the end wall overtakes the front. However, the propagation of the density current is retarded compared with the experimental results. Two-dimensional modeling seems to have an effect on underestimating the front velocity of the density current.

• Composites Research
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• v.31 no.6
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• pp.323-331
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• 2018

The effect of stainless steel jagged-pin reinforcement on the pull-off strength of the composite hat-joint was studied by the test. The pins were physically and chemically surface-treated and inserted in the thickness direction over the interface where the skin and stiffener meet. The specimens including the jagged-pins were made by co-curing process. Diameters of the jagged-pins were 0.3, 0.5 and 0.7 mm. The pin areal densities were set to 0.5 and 2.0% based on the interface area where the skin and stiffener meet. The specimens using 0.3 mm diameter normal (un-jagged) pins with 2.0% areal density were additionally fabricated and tested to investigate the pin shape effect on the pull-off strength. The pull-off strengths of specimens reinforced with 0.5% areal density by 0.3, 0.5, and 0.7 mm diameter pins were 45, 19 and 9% higher than those of un-reinforced specimens, respectively. In case with 2.0% pin areal density, the strengths were 127, 45, and 11% higher than those of un-reinforced specimens, respectively. The test results show that the higher pin areal density results in the higher strength when the pin diameter is the same. When the pin areal density is the same, the smaller pin diameter leads to higher strength. When the joints using jagged-pins and normal pins in 2.0% areal density with 0.3 mm diameter, the joints of jagged-pins showed the 64% higher strength. From the results of this study, it was confirmed that jagged-pin reinforcement can be an effective method for improving the pull-off strength of composite hat-joint.

• Journal of the Korean Institute of Gas
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• v.11 no.2 s.35
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• pp.31-36
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• 2007

In order to study on the corrosion characteristics of STS 304 pipeline steel weldment for gas cooling & heating system. the electrochemical polarization test and corrosion test by impressed potential in 0.5M $H_2SO_4+0.01M$ KSCN solution was carried out. Also, SEM and hardness of welding zone was measured. And then passive behavior, corrosion behavior by the impressed potential and SEM aspect and hardness behavior of base metal(BM) and heat affected zone(HAZ) for STS 304 pipe were investigated. The main results are as follows: 1) The critical anodic current density of heat affected zone(HAZ) is drained more highly than that of base metal(BM), and primary passive potential of HAZ become higher than that of BM. 2) The passive current density of TUE is drained more highly than that of BM, and passive region of BM become bigger than that of HAZ. 3) By the impressed potential, the current density of HAZ is drained more than that of BM.

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.10a
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• pp.123-123
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• 2021

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.04a
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• pp.65-65
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• 2021

• Proceedings of the KOR-KST Conference
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• 1998.10a
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• pp.3-10
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• 1998

본 연구에서는 동적통행시간예측을 위한 하나의 방법으로 블록밀도법을 도입하여 가로상의 일정한 구간을 세분화하고 몇 개의 블록으로 분할한 후 교통류를 유체근사화시키고 각 블록의 밀도를 일정시간 마다 갱신해 나가는 방법을 채택하였다. 즉, 각 블록에서 주어진 밀도의 초기치와 최하류부의 블록에서 유출교통량을 이용하여 일정시간 간격으로 모든 블록에서의 밀도를 수정해 가는 유체의 연속방정식의 개념을 도입하였다. 또한, 본 연구에서는 첨단교통시스템에 적용될 동적통행시간 예측을 위해 기존의 연속교통류만을 대상으로 하던 것에서 벗어나 신호등을 포함한 단속교통류를 대상으로 하였다. 또한 교통류의 저밀도 구간과 고밀도 구간을 분리하여 Ele복합모형을 적용하여 교통류를 해석하고 가급적 실제 상황과 유사하게 근접시키고자 하였다. 이 이론을 근거로 구축된 모델에 실제 현장에서 얻어진 교통량, 밀도, 속도 등의 자료들을 투입하고 통행시간의 예측을 도모하였다.

• 한국지구과학회:학술대회논문집
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• 2005.02a
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• pp.147-152
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• 2005

인공구조물인 댐체의 밀도 분포를 밝히기 위하여 사력댐에서 고정밀중력탐사를 수행하였다. 얻어지는 중력이상값이 매우 작은 양이므로 정밀한 지형보정을 위하여 삼각요소법을 도입하였다. 역산을 위해서도 댐체의 모양을 그대로 반영할 수 있도록 임의 다면체로 구성하였고, 글로벌 역산인 ASA를 이용하여 해석하였다. 해석결과는 댐의 코어 부분과 모래와 암석으로 채워진 부분이 명확히 구분되었고, 댐의 중앙부에 상대적인 저밀도가 존재하는 수평적인 밀도 변화도 확인할 수 있었다.

• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.76-76
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• 2023

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.125-130
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• 2021

In the AAPM CT performance phantom, there is little data on the CT number of the effective atomic number and physical density corresponding to each peg and water of the CT number calibration insert. Therefore, the necessity of documentation was raised.The purpose of this study is to calculate the effective atomic number for each peg and water of the CT number calibration insert in the AAPM CT performance phantom, and to measure the CT number for the calculated effective atomic number and physical density for comparative analysis.In order to obtain CT number data on the effective atomic number and physical density of each peg and water from the CT number calibration insert of the AAPM CT performance phantom, the effective atomic number for each peg and water was first calculated. Then, CT slices were obtained by scanning the CT number calibration with a CT scanner. CT numbers were measured for each peg and water in the central CT slice. As a result, the CT numbers for the effective atomic number showed a nonlinear pattern of repeating the increase and decrease as the effective atomic number increased. In addition, the CT numbers for physical density showed a nonlinear pattern of repeating the increase and decrease as the physical density increased.