• Asian Journal of Turfgrass Science
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• v.15 no.4
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• pp.169-179
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• 2001

This study was conducted to determine the effect of root zone cooling on growth and quality of turfgrasses including Kentucky bluegrass (Poa pratensis L.‘Nuglade’), perennial ryegrass (Lolium perenne L.‘Accent’), tall fescue (Festuca arundinacea Schreb.‘Pixie’), and Japanese lawngrass (Zoysia japonica Steud.) in simulated athletic field during summer season in Korea. Mineral contents in clippings of turfgrasses grown at different soil mixtures and temperatures were also analyzed. Root zone cooling (approximately 4~6$^{\circ}C$ lower than that of untreated-control) resulted in good uniformity, little disease incidence and higher level of chlorophyll contents in cool-season turfgrasses. The effectiveness of root zone cooling in protecting disease incidence from high temperature stress was the most manifest in perennial ryegrass compared to others. Fresh clipping weight in treatment of root zone cooling was increased approximately 2 times in Kentucky bluegrass and perennial ryegrass, and 2.5 times in tall fescue compared to those of control. There was higher growth rate in a soil mixture composed of 80% peat moss ＋10% sand ＋10% soil (v/v/v) than in that of 80% pea moss ＋20% sand (v/v), Mineral contents of N, P, K, Ca, and Mg in clippings of three species of cool-season turfgrasses were significantly increased in treat-ment of root zone cooling but this was not found in Japanese lawngrass. Results showed that root zone cooling has a benefit in keeping good quality and growth of cool-season turfgrasses in sports field under supraoptimal ambient temperature during summer season.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.3
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• pp.175-182
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• 2009

The spent cationic exchange resins and anionic exchange resins were separated from mixed spent exchange resins by a fluidized bed gravimetric separator. The separated resins were identified by an elemental analysis and thermogravimetric analysis. The each test sample was prepared by diluting the slurry made by wet ball milling the cationic exchange resins and the anionic exchange resins separated as a spherical granular form for 24 hours. The resulting test samples showed a slurry form of less than $75{\mu}m$ of particle size and 25,000ppm of $COD_{cr}$. The decomposition conditions of each test samples from a thermal power plant were obtained with a lab-scale(reactor volume : 220mL) supercritical water oxidation(SCWO) facility. Then pilot plant(reactor volume : 24 L) tests were performed with the test samples from a thermal power plant and a nuclear power plant successively. Based on the optimal decomposition conditions and the operation experiences by lab-scale facility and the pilot plant, a commercial plant(capacity : 150kg/h) can be installed in a nuclear power plant was designed.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.270-277
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• 2002

Since founded in 1959, it's well known that the KAPD has pioneered in the researches and clinical aspects of pediatric dentistry in Korea. It's official journal, the Journal of the KAPD, was first published in 1974 and has pressed total 956 articles up to now(March, 2001). In this study, all the articles pressed in this journal have been surveyed, focussing in their main theme, their chronological and thematic distribution. The thematic classification was made with the reference of the previous studies and renowned textbooks in pediatric dentistry. And we obtained the results as follows: 1. The researches on dental materials and dental equipments have shown continuous increase throughout the period. 2. The researches on dental caries, caries prevention and systemic disorders have occupied relatively high proportion consistently. 3. The researches on malocclusions and cysts/minor surgery have shown increasing tendency in the second period, but are decreasing in the third period. 4. The researches on craniofacial growth/development, tooth development/eruption, developmental disorders of teeth, management of eruption space have shown decreasing tendency. 5. The researches on behavioral research, oral habits, occlusion of primary-mixed dentition have shown very low proportion, reaching no more than 1% throughout the period.

• KSBB Journal
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• v.23 no.3
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• pp.245-250
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• 2008

The treatment of a model wastewater containing quinoline in an integrated wet oxidation-aerobic biological treatment was investigated. Partial wet oxidation under mild operating conditions was capable of converting the original quinoline to biodegradable organic acids such as nicotinic, formic and acetic acid, the solution of which was subjected to the subsequent aerobic biological treatment. The wet oxidation was carried out at 250$^{\circ}C$ and the initial pH of 7.0, and led to effluents of which nicotinic acid was oxidized through 6-hydroxynicotinic acid by a Bacillus species in the subsequent aerobic biological treatment. Either homogeneous catalyst of $CuSO_4$ or phenol, which is more degradable in the wet oxidation compared to quinoline, was also used for increasing the oxidation rate in the wet oxidation of quinoline at 200$^{\circ}C$. The oxidation of quinoline in the catalytic wet oxidation and the wet co-oxidation with phenol resulted in effluents of which nicotinic acid was biodegradable earlier in the aerobic biological treatment compared to those out of the non-catalytic wet oxidation at 250$^{\circ}C$. However, the lag phase in the biodegradation of nicotinic acid formed out of the wet oxidation at 250$^{\circ}C$ was considerably shortened after the adaptation of Bacillus species used in the aerobic biological treatment with the effluents of the quinoline wet oxidation.

• Membrane Journal
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• v.23 no.2
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• pp.112-118
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• 2013

Polyancrylonitrile nanofiber membrane (PAM) was prepared by using the electrospinning method with a solution of polyacrylonitrile (PAN) in DMF. The pore-diameter of PAMs and the number of PAM's layer were controlled for the microfiltration (MF) application. In addition, in order to improve the water-flux, AN-PEGMA copolymers have been synthesized via free radical polymerization with poly (ethylene glycol) methyl ether methacrylate and azobisisobutylronitrile (AIBN), and then PAN/AN-PEGMA nanofiber membranes (PAM/APM) were prepared by electrospinning with a mixture of PAN (9 wt%) and AN-PEGMA (3 wt%) in DMF (88 wt%). The prepared membranes were investigated with FT-IR and E.D.S. It was confirmed through scanning electron microscope (SEM), porometer, and porosity analysis that the porous membrane with a uniform diameter (400~600 nm) and a uniform pore characteristics (0.5~0.4 ${\mu}m$) was prepared. For the MF application, water-flux measurements were investigated and then the result was shown that the water permeability value of PAM/APMs introduced AN-PEGMA copolymers was relatively higher than that of the PVdF commercial membrane. From these results, PAN nanofiber membranes prepared by electrospinning could be utilized as a MF membrane.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.421-427
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• 2015

In this study, we have observed the change of the Hounsfield (HU) in the alteration of by changing in size of physical area and setting size of region of interest (ROI) at focus on kVp and mAs. Four-channel multi-detector computed tomography was used to get transverse axial scanning images and HU. Three dimensional printer which is type of fused deposition modeling (FDM) was used to produce the Phantom. The structure of the phantom was designed to be a type of cylinder that contains 33 mm, 24 mm, 19 mm, 16 mm, 9 mm size of circle holes that are symmetrically located. It was charged with mixing iodine contrast agent and distilled water in the holes. The images were gained with changing by 90 kVp, 120 kVp, 140 kVp and 50 mAs, 100 mAs, 150 mAs, respectively. The 'image J' was used to get the HU measurement of gained images of ROI. As a result, it was confirmed that kVp affects to HU more than mAs. And it is suggested that the smaller size of physical area, the more decreasing HU even in material of a uniform density and the smaller setting size of ROI, the more increasing HU. Therefore, it is reason that to set maximum ROI within 5 HU is the best way to minimize in the alteration of by changing in size of physical area and setting size of region of interest.

• Clean Technology
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• v.29 no.4
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• pp.305-312
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• 2023

Due to the strengthening of environmental requirements, aging denitrification facilities need to improve their performance. The present study aims to suggest the possibility of improving performance using computational analysis techniques. This involved modifying both the geometric design and the operating conditions, including the flow path shape of the equipment such as the inlet guide vane and the curved diffusing part, and the flow control of the ammonia injection nozzle. The conditions presented in this study were compared with existing operating conditions in terms of the flow uniformity, the NH₃/NO molar ratio of the mixed gas flowing into the catalyst layer, and the total pressure drop of the facility. The flow field applied in the computational analysis ranged from the outlet of the economizer in the combustion furnace to the inlet of the air preheater, the full domain of the denitrification facility. The performances were derived by solving the flow fields using ANSYS-Fluent and the injection amount of ammonia was adjusted for each nozzle using Design Xplorer. Compared to the denitrification performances of the equipment currently in operation, the conditions proposed in this study showed an improvement in the flow uniformity and NH₃/NO composition ratio by 45.1% and 8.7%, respectively, but the total pressure drop increased by 1.24%.

• Composites Research
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• v.26 no.4
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• pp.254-258
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• 2013

Polypropylene films reinforced with multi-walled carbon nanotubes and exfoliated graphite nanoplatelets were fabricated by extrusion, and the effects of filler type and take-up speed on the mechanical properties and microstructure of composite films were investigated. Differential scanning calorimetry revealed that the addition of carbon nanomaterials resulted in increased degree of crystallinity. However, increasing the take-up speed reduced the degree of crystallinity, which indicates that tension-induced orientations of polymer chains and carbon nanomaterials and the loss of degree of crystallinity due to rapid cooling at high take-up speeds act as competing mechanisms. These observations were in good agreement with tensile properties, which are governed by the degree of crystallinity, where the C-grade exfoliated graphite nanoplatelet with a surface area of $750m^2/g$ showed the greatest reinforcing effect among all types of carbon nanomaterials used. Scanning electron microscopy was employed to observe the carbon nanomaterial dispersion and orientation, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.83.2-83.2
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• 2010

평판형 고체산화물 연료전지(planar SOFC : Solid oxide Fuelcell)는 높은 전류 효율 및 출력밀도를 가지는 중,대형 발전용 전기소자이다. SOFC 스택을 600~800도에서 작동할 경우, 금속 분리판에서 휘발된 크롬에 의한 열화현상과 금속의 산화에 의한 표면 저항의 증가가 큰 문제점으로 알려져 있으며, 이를 개선하기 위한 많은 연구가 진행되고 있다. 본 연구에서는 금속 분리판의 열화를 억제하기 위한 여러 보호코팅의 특성을 밝히고, 특성차이의 원인을 분석하고자 하였다. 모재는 상용 STS444합금 (Nisshin steel 생산) 2.0mmt 박판을 사용하였으며, 표면 상태를 균일하게 하기 위하여 표면은 동일한 #1200 번 사포로 연마후 코팅하였다. 적용한 코팅은 전기도금 Ni 코팅, (MnCo)3O4 wet powder spray 코팅, (MnCo)3O4 ADM코팅 3종이었으며, 코팅층의 두께는 최적 공정조건에 따라 달리 하였다. 산화후 형성되는 표면 산화물의 전기적 특성을 평가하기 위하여 시험편의 비면적 저항 (ASR : area specific resistance)을 장시간 측정하였다. 측정편의 크기는 가로 4cm ${\times}$ 세로 4cm였으며, 100시간 공기중 산화후 측정하였다. 표면 접촉을 높이기 위하여 Pt paste를 40~50um도포하였으며, 1~0.1A인가된 전류에 대한 저항을 4전극법 (4-probe)으로 측정하였다. 표면 코팅층이 크롬 휘발을 억제하는 정도를 평가하기 위하여 크롬 휘발량을 측정하였다. 시편은 가로 1.5cm ${\times}$ 세로 1cm 였으며, 공급된 공기와 수분의 혼합가스와 응축기 표면에 흡착된 크롬의 양을 ICP-MASS법으로 측정하였다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.170-170
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• 2017

기후변화 따른 스마트팜 돈사 외부 환경의 변화에 대응하고, 사육 환경을 능동적으로 개선하기 위한 연구가 수행 중이다. 돈사 내 열전달 요소 간 상호 역학성 분석을 위해서 고려해야할 사항은 입기구, 보온 등, 열풍기, 단열제, 위치, 방향, 돈사의 연평균 온도, 습도, 연중 일사량, 가축의 열복사 등 상호 복잡하게 연관되어 있는 물리량이다. 돈사 전체 열손실, 자연발생 에너지량, 강제발생 에너지량, 난방용량 등을 고려한 순간 열부하 산정을 위한 여러 방법 중 우선적으로 CFD(Computational Fluid Dynamics)를 이용하였다. 순간 열부하 산정을 위한 해석 도구 선정에 있어서 다양한 유체 및 기체 전산 유체역학 Solver(Fluent, Open-FOAM, Blender)를 고려하였다. 공간 Mech를 수행하기 위한 도구로는 공개 소프트웨어 인 FreeFem++ 3.51-4 (http://www.freefem.org)를 이용하였다. 이 과정에서 일부 기체 (암모니아)의 농도를 난수로 변화시키는 기법을 적용하여 가상적으로 돈사의 환경을 Pseudo 시뮬레이션 하였다. 결과적으로 Fluent에 비하여 OpenFOAM을 이용하여 얻은 열유동의 방향(속도)과 크기 백터가 상대적으로 크게 나타났다. Fluent가 시계열 상에서 혼합 기체 물리량 변화를 무시할 수 있는 안정되고 균일한 환경에 적합하기 때문인 것으로 판단되었다. Blender의 경우 Lattice Boltzmann methods 과 Smoothed-particle hydrodynamics 방법을 이용한 유체/입자 동력학 모델링을 제공함에 있어 시각적 효과를 강조하는 기능에 중점을 두었다. Fluent와 Blender에서 제공하는 해석 연산 모듈의 정확성 검증을 위해선 공간 분해능을 높인 정밀 계측 시스템을 이용하여 검증할 필요가 있다. Open-FOAM를 이용한 열부하 분석 수행이 상대적으로 높은 절대값을 보이는 특성은 열부하 제어 시스템의 Overshoot를 유발할 가능성이 있으므로 이에 대한 해석 모델의 보정이 추가적으로 필요할 것이다. CFD의 한계인 시간 복잡도를 낮추고 상대적으로 높은 시계열 분해능을 확보할 경우 돈사 내 환기시스템에 맞는 소요 환기량 실시간 산정이 가능해지고 외부기상 및 돈사내부 복사열을 활용함과 동시에 돈군 순환에 상응하는 실시간 열부하 관리 시스템 도출이 가능할 것이다.