• 한국태양에너지학회 논문집
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• 제40권5호
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• pp.23-34
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• 2020

Concentrator photovoltaic (CPV) system consists of high-quality complex optical elements, mechanical devices, and electronics components and can have the advantages of high integration and high-efficiency energy sources. III-V compound semiconductor cells have proven performance based on high reliability in the aerospace field, but have characteristics that require absolute support of the balance of systems (BOS) such as solar position trackers, receivers with heat sinks, and housing instruments. To determine the optimum parameters of secondary optical elements (SOEs) design for CPV systems, we designed three types of CPV modules, classified as non-SOEs type, reflective mirror type, and CPC lens type. We measured the I-V and P-V characteristics of the prototype CPV modules with the angle of inclination varying from 0° to 12° and with a 500-magnification Fresnel lens. The experimental results assumed misalignment of the solar position tracker or module design of pinpoint accuracy. As a result, at the 0° tilt angle, the CPC lens produced lower power due to the quartz transmittance ratio compared to that by other SOEs. However, for tilt angles greater than 3°, the CPC lens type module achieved high efficiency and stability. This study is expected to help design high-performance CPV systems.

• The Journal of Korean Physical Therapy
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• 제24권6호
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• pp.414-418
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• 2012

Purpose: Muscle fatigue affects proprioception, and it causes problems in spinal stability. The purpose of this study was to examine the effect on the accuracy of reproducing the lumbar angles before lumbar exercise and after fatiguing isokinetic lumbar exercise. Methods: Thirty healthy adults participated in this study. Before induction of fatigue by exercise, the proprioception was measured by Biodex. Lumbar positions were passively maintained on stimulation position ($25^{\circ}$ flexion and $25^{\circ}$ extension), and back to the starting position. Subjects actively repositioned the remembered stimulation position, and error degrees between the stimulation position and reposition were measured. Using an isokinetic device at $120^{\circ}$/sec of velocity of angle lumbar flexion/extension exercise resulted in muscle fatigue. The post-fatigue proprioceptive position sense was used in the same way as in pre-fatigue measurement. Results: Means of position sense of pre-fatigue were $2.19{\pm}1.97$ on flexion angle, and $5.04{\pm}2.84$ on extension angle. After exercise induced fatigue, means of position sense were $2.37{\pm}1.83$ on flexion angle, and $4.93{\pm}2.57$ on extension angle. Results of this study showed significant differences of lumbar proprioceptive position sense between pre- and post-fatigue. Conclusion: Lumbar proprioception sense in active repositioning in flexion and extension was affected in the presence of muscle fatigue. Therefore, it should be noted that therapeutic exercise for patients with abnormal proprioceptive sense or elderly people must be performed with care because muscle fatigue can cause secondary damage.

• 한국산림과학회지
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• 제80권4호
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• pp.383-392
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• 1991

경북지방(慶北地方)의 소나무와 곰솔에 대한 Giemsa C-분염(分染)에 의한 유전변이(遺傳變異)를 조사(調査)한 바 다음과 같다. 1. Giemsa C-분염(分染)에 의한 핵형분석(核型分析)에서 소나무와 곰솔의 체세포(體細胞) 염색체수(染色體數)는 2n=24이고 2. 소나무는 arm ratio가 비슷한 M형(型)으로 개체간(個體間)에는 큰 차이가 없었으나 이차협착(二次狹窄)의 수(數)와 위치(位置)가 개체간(個體間)에 다소(多少) 차이(差異)가 있었으며 3. 곰솔은 염색체(染色體) 길이와 arm ratio가 M형(型)으로 소나무와 비슷하고 이차협착(二次狹窄)의 수(數)와 위치가 비슷하여 개체간(個體間)의 변이(變異)는 거의 없었다. 4. 염색체(染色體) C-분염(分染)에 의한 유전변이(遺傳變異)에서 소나무와 곰솔은 12쌍(雙)의 염색체(染色體)에 동원체(動原體) 부분(部分)과 이차협착(二次狹窄) 부위(部位)에 band가 나타났고 5. 소나무는 3번, 4번, 7번 염색체(染色體)에서는 개체(個體)에 관계(關係)없이 모두 이차협착(二次狹窄)에 band가 나타나고 1번, 2번, 5번 염색체(染色體)의 이차협착(二次狹窄)의 band는 개체간(個體間)에 변이(變異)가 있었다. 8번, 9번, 10번, 11번 염색체(染色體)에서는 telomere에 band가 나타나고 개체간(個體間)에 변이(變異)가 있었으며 6. 곰솔은 2번, 3번, 5번, 7번 8번 염색체(染色體)의 이차협착(二次狹窄)에 band가 모두 나타나고 개체간(個體間)에 변이(變異)가 없었으며 telomere에는 band가 나타나지 않았다. 7. C-분염(分染)에 의한 변이(變異)는 소나무에서는 개체간(個體間)에 변이(變異)가 있으나 곰솔에서는 변이(變異)가 없었고 소나무는 4번 염색체(染色體)에서, 곰솔은 8번 염색체(染色體)에서 이차협착(二次狹窄)에 band가 나타나고 있다. 이러한 것이 소나무와 곰솔의 C-분염(分染)에 의한 차이점(差異點)이라고 생각된다.

• 한국연소학회지
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• 제4권1호
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• pp.1-15
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• 1999

In order to analyze the sensitivity on the pulverized coal flames of the several variables, a numerical study was conducted at the gasification process. Eulerian approach is used for the gas phase, whereas lagrangian approach is used for the solid phase. Turbulence is modeled using the standard $k-{\varepsilon}$ model. The turbulent combustion incorporates eddy dissipation model. The radiation was solved using a Monte-Carlo method. One-step two-reaction model was employed for the devolatilization of Kideco coal. In pulverized flame of long liftoff height, the initial turbulent intensity seriously affects the position of flame front. The radiation heat transfer and wall heat loss ratio distort the temperature distributions along the reactor wall, but do not influence the reactor performance such as coal conversion, residence time and flame front position. The primary/secondary momentum ratio affects the position of flame front, but the coal burnout is only slightly influenced. The momentum ratio is a variable only associated with the flame stabilization such as flame front position. The addition of steam in the reactor has a detrimental effect on all the aspects, particularly reactor temperature and coal burnout.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.195-198
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• 2002

A positron camera, consisting of a pair of Anger-type scintillation detectors, has been developed for verifying the ranges of irradiation beams in heavy-ion radiotherapy. Images obtained by a centroid calculation of photomultiplier outputs exhibit a distortion near the edge of the crystal plane in an Anger-type scintillation detector. The images of a $\^$68/Ge line source were detected and look-up tables were prepared for the position correction parameters. Asymmetry of the position distribution detected by the positron camera was prevented with this correction. As a result, a linear position response and a position resolution of 8.6 mm were obtained over a wide measurement field.

• 한국의학물리학회지:의학물리
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• 제21권4호
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• pp.311-322
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• 2010

양성자 치료 시, 이차 입자는 암 부위 이외의 영역에 선량을 전달하고 이차 암 발생 가능성을 내재하기 때문에 이에 대한 정확한 분석은 중요한 역할을 한다. 본 연구의 목적은 불균질 물질에 의해 양성자 빔으로부터 발생 된 이차입자의 플루언스와 에너지 분포가 받는 영향에 대해 Geant4 (Geometry And Tracking) 전산모사를 통해 분석 하는 것이다. 불균질 조건은 브래그 커브 내에 최대 선량의 30% (플라토)와 80% (브래그 피크) 선량 지점에 두께 2 cm의 지방, 뼈 그리고 폐 등가 물질을 삽입하여 구성하였다. 또한, 양성자의 에너지는 100, 130, 160 그리고 190 MeV로 변화시켰으며, 이차 입자에 대한 결과는 불균질 물질에서의 이차입자의 플루언스와 에너지 분포로 나타내었다. 이차입자의 플루언스는 불균질 물질의 밀도에 적은 영향을 받지만, 삽입위치, 양성자의 초기 에너지에 따라서는 영향을 받지 않는다. 이차입자의 에너지 분포는 불균질 물질의 삽입 위치에 따라 다르다. 플라토 영역 내에서 이차입자의 에너지 분포는 물질의 밀도에 영향을 받지만, 브래그 영역 내에서는 불균질 물질의 밀도와 양성자의 초기 에너지에 영향을 받는다. 본 연구는 더욱 복잡한 불균질 물질에서의 이차입자의 분포에 대한 예측 가능성을 내제한다.

• 한국미생물·생명공학회지
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• 제38권4호
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• pp.475-480
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• 2010

Actinomycetes are Gram-positive soil bacteria and one of the most important industrial microorganisms due to superior biosynthetic capabilities of many valuable secondary metabolites as well as production of various valuable bioconversion enzymes. Among them are cytochrome P450 hydroxylase (CYP), which are hemoproteins encoded by a super family of genes, are universally distributed in most of the organisms from all biological kingdoms. Actinomycetes are a rich source of soluble CYP enzymes, which play critical roles in the bioactivation and detoxification of a wide variety of metabolite biosynthesis and xenobiotic transformation. Cyclosporin A (CyA), one of the most commonly-prescribed immunosuppressive drugs, was previously reported to be hydroxylated at the position of 4th N-methyl leucine by a rare actinomycetes called Sebekia benihana, leading to display different biological activity spectrum such as loss of immunosuppressive activities yet retaining hair growth-stimulating side effect. In order to improve this regio-selective CyA hydroxylation in S. benihana, previously-identified several secondary metabolite up-regulatory genes from Streptomyces coelicolor and S. avermitilis were heterologously overexpressed in S. benihana using an $ermE^*$ promoter-containing Streptomyces integrative expression vector. Among tested, SCO4967 encoding a conserved hypothetical protein significantly stimulated region-specific CyA hydroxylation in S. benihana, implying that some common regulatory systems functioning in both biosynthesis and bioconversion of secondary metabolite might be present in different actinomycetes species.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권4호
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• pp.401-406
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• 1999

편측성 혹은 양측성 구순구개열환자에서 일차 구순 성형술후 나타나는 이차 구순 기형은 세심한 관찰을 통한 문제점에 대한 정확한 인식을 통해 상순, 홍순부, 피부와 근육등의 적절한 교정술로 심미성, 기능적 회복을 이룰 수 있다. 저자들은 이차 구순 기형으로 나타난 구륜근의 부정유합, 휘파람 변형과 부족한 입술등에 대해 적절한 성형술로 심미적, 기능적으로 양호한 결과를 얻었기에 보고하는 바이다.

• 한국레이저가공학회지
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• 제16권3호
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• pp.11-21
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• 2013

As parts are becoming more complex and smaller with the development of new materials, high-quality laser precision processing is getting the limelight. Laser enables quick processing and less deformation of materials. It also enables welding with diverse materials. In this study, the pole rod and tap for the secondary battery were laser-welded using cross and coaxial nozzles. The results of the comparative analysis of cross and coaxial nozzles according to the processing parameters showed that the coaxial nozzle had more sensitive welding characteristic to the nozzle position or pressure than the cross nozzle. This indicated that the processing parameters should be carefully determined for the welding with the coaxial nozzle. The pole rod and tap were welded together in a form of T joint to improve the output of the secondary battery, and the cross nozzle had a better welding characteristic than the coaxial nozzle.

• 대한기계학회논문집B
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• 제23권5호
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• pp.687-694
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• 1999

An experimental study was carried out in two laboratory-scale reactors to investigate the effect of heating rate on the behavior of flame front in a pulverized coal flame. Each. reactors had different heating mechanisms. For reactor A losing large heat through transparent quartz wall. pulverized coal particles were ignited by secondary air of 1050K. Flame front could be visualized through the transparent wall. Reactor B was insulated with castable refractory to minimize the heat loss through the reactor wall and accompanied with secondary air of 573K. Flame front was estimated from the gas temperature and species concentration measured using R-type thermocouple(Pt-Pt/Rh 13%) and gas chromatograph at various coal-air ratios and swirl intensities. The flame front position was closely related with the magnitude of heating rate. The heating rate for lifted flame was of the order of $10^4$ to $10^5K/s$ and for coal Ignition at least over $10^4K/s$. The heating mechanism had little impact on the extinction limits. The weak swirl number of 0.68 forced the flame front to move toward the upstream by the rapid mixing of coal and air. The primary/secondary momentum ratio was an inappropriate variable to distinct the liftoff of flame.