• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.439-439
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• 2012

ZnO 나노로드는 큰 밴드갭 에너지(~3.37 eV)와 60 meV의 높은 엑시톤 결합 에너지(exciton binding energy)를 갖고 있으며, 우수한 전기적, 광학적 특성을 지닌 1차원 나노구조의 금속산화물로서 태양전지 및 광전소자 널리 응용되고 있다. 이러한 ZnO 나노로드를 성장하는 방법 중에 전기화학증착법(electrochemical deposition method)은 전도성 물질위에 증착된 시드층(seed layer)을 성장용액에 담그어 전압을 인가하여 만들기 때문에 기존의 수열합성법(hydrothermal method), 졸-겔 법(sol-gel method)보다 비교적 간단한 공정과정으로 저온에서 빠르게 물질을 성장시킬 수 있는 장점이 있다. 한편, 디스플레이 산업에서 ITO (indium tin oxide)는 투명 전도성 산화물(transparent conductive oxide)로써 가시광 파장영역에서 높은 투과율과 전도성을 가지며, 액정디스플레이, LED (Light emitting diode), 태양전지 등의 다양한 소자에 투명전극 재료로 쓰이고 있다. 또한 최근 ITO를 유연한 PET (polyethylene terephthalate) 기판 위에 증착은 얇고, 가볍고, 휘어지기 쉬워 휴대하기 편하기 때문에 차세대 광전자소자 응용에 가능성이 크다. 본 연구에서는 ZnO 나노로드를 ITO/PET 기판위에 전기화학증착법으로 성장하여, 구조적 및 광학적 특성을 분석하였다. 시드층을 형성하기 위해 RF 마그네트론 스퍼터를 이용하여 ~20 nm 두께의 ZnO 박막을 증착시킨 후, zinc nitrate와 hexamethylenetetramine이 포함된 수용액에 시료를 담그어 전압을 인가하였다. 용액의 농도와 인가전압을 조절하여 여러 가지 성장조건에 대한 ZnO 나노로드의 구조적, 광학적 특성을 비교하였다. 성장된 시료의 형태와 결정성을 조사하기 위해, field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD)을 사용하였으며, UV-vis-NIS spectrophotometer, photoluminescence (PL) 측정장비를 사용하여 광학적 특성을 분석하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.458-465
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• 2011

UAV-UGV teaming concept has been proposed that can compensate for weak points of each platform by providing carrying, launching, recovery and recharging capability for the VTOL-UAV through the host UGV. The teaming concept can expand the observation envelop of the UGV and extend the operational capability of the UAV through mechanical combination of each system. The spherical-shaped coaxial rotorcraft UAV is suggested to provide flexible and precise interface between two systems. Hybrid navigation solution that included vision-based target tracking method for precision landing is investigated and its experimental study is performed. Feasibility study on length-variable rotor to provide the compact configuration of the loaded rotorcraft platform is also described.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2001.02a
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• pp.14-18
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• 2001

현대의 우리들의 생활환경 중에는 약 10만 종류 이상의 아주 많은 화학물질이 존재하고 있으며 매년 약 1000종류의 새로운 화합물이 상품화되고 있다고 알려져 있다. 이들 중 일부는 우리의 일상생활에 편리한 기능을 가져다 주는 역할을 하고 있으나 최근 생태계 및 인체에 유해한 영향을 미치는 물질로 판명되는 사례가 증가하고 있다. 그들 중에는, 성호르몬과 유사한 구조를 가지기 때문에 호르몬 수용체에 잘못 결합하여 호르몬 활성을 異常히 높이는 등의 영향을 미치는 것이 알려져 있으며, 또, 약물대사 효소의 유도나 효소활성의 저해 등에 의한 물질대사의 교란, 면역계통의 저해, 발암작용 등의 영향에도 미치는 것이 알려져 있다. 이러한 일군의 물질은 내분비계 장애물질(Endocrine disruptors; 환경 호르몬)로 불리며, 최근의 여성에 있어서 유방암의 발생율의 상승이나 남성의 정자수의 감소, 혹은 어떤 종의 야생 생물에 있어서 생식기능 장해(악어 수컷 생식기의 퇴화, 수컷 잉어등의 암컷화, 일부 권패류의 임포섹스 등)는 이러한 내분비계 장애물질에 의하여 유발되고 있다고 하는 가능성이 지적되고 있다. 그렇지만, 이러한 내분비계 장애물질의 환경 중에서의 분포나 다양한 생물에의 영향에 관한 연구는 세계적으로도 아직 부족하고 내분비계 장애물질의 실태나 그 메카니즘 및 그것이 가지는 의미에 대하여는 아직 명확하게 규명되어 있지 않고 있어, 그것에 의한 생체영향의 평가를 총합적으로 검토하기까지에는 이르지 않고 있다. 이러한 물질에 관한 연구는 최근 선진국을 중심으로 활발한 연구가 수행되고 있으나, 우리 나라에 있어서의 연구는 지금까지는 아직 미미한 수준에 머물고 있다. 따라서, 이러한 내분비계 장애물질을 빠른 시기에 발견하여 그것들에 의한 영향을 평가하고, 그 영향을 미연에 방지하는 데에 필요한 대책을 강구하기 위한 많은 연구가 필요 불가결하다. 본고에서는 이러한 환경호르몬 물질 중 본 연구실에서 수행한 내용을 중심으로 유해화학물질 오염 및 대책에 대하여 간단히 발표하고자 한다. 발표내용은, 남해안을 중심으로 조사한 유기주석화합물 오염, 광양만에서의 PAHs(다환방향족탄화수소류) 및 Bisphenol A 오염에 관한 연구결과와 이러한 유해화학물질 오염을 평가하고 관리하는 하나의 유용한 방법으로서 위해성 평가에 대하여 실례를 중심으로 간단히 소개하고자 한다.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.522-525
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• 1985

The dried soymilk residue (SMR) was added into soybean water extract in order to investigate its effect on physical characteristics of soybean curd. As the mixing ratio (d. b.) increased, the volume and water holding capacity of the curd was reduced and penetration value was increased. However, the Sag value was rather increased until 20% of mixing ratio reached and then decreased drastically by 30% addition of SMR. The overall physical and sensory quality showed that substitution of soybean with SMR by 10% was recommendable without significant unfavorable change in quality of soybean curd. The proposed method of absorption of unbound water on filter paper was proved to be simple and reliable for measurement of water holding capacity of soybean curd.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.474-479
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• 2016

As the Eco-energy is recently required, electrical energy is fast increased. Several induction heating methods are attractive for Eco-energy and energy saving. In this paper, electrical fan heater was designed and developed with new concept for energy saving by electromagnetic induction heating. Proposed system was composed of three module, blast part, induction heating part and power transformation part. Induction heating method was adapted for heating and the resonant inverter was used for increasing of the power transformation efficiency. Full-bridge resonant inverter was adopted to resonant inverter. This system was composed of induction heating part made with metal(SUS 40 series), and power transformation part made with rectifier module, filter module and resonant inverter. From these results, the proposed new electric heater could be saved the energy from faster increasing the temperature compared to commercial gas and other electric heater. This electrical fan heater is possible to be used in field of home, commercial and agricultural area for eco-energy saving heater.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.818-826
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• 2012

In this paper, the improvement methods of the computational efficiency of the conjunction screening algorithm, which calculates the closest distance between primary satellite and space objects are presented. First method is to use GPU(Graphics Processing Unit) that has high computing power and handles quickly large amounts of data. Second method is to use Apogee/Perigee filter which excludes non-threatening objects that have low probability of collision and/or minimum distance rather than that of thresh hold. Third method is to combine first method with second method. As a result, the computational efficiency has been improved 34 times and 3 times for the first method only and second method only, respectively. On the contrary, the computational efficiency has been dramatically improved 163 times when two kinds of methods are combined.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.521-526
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• 2016

Some thiadiazole and dithiocarbamate derivatives were desinged and synthesized in order to study the potential use as anti- wear additives. Their anti-wear properties in three different base oils (DB-51, soybean, and 100 N) were evaluated using a four-ball wear tester (ASTM D4172). The solubilities of dithiocarbamate derivatives in the base oils were better than those of thiadiazole derivatives. The compounds containing oleoyl group rather than nonanoyl group gave good anti-wear properties. The solubilities and anti-wear properties were explained by the polarity of the compounds.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.757-761
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• 1995

The relationship between the molecular structure of rice starch and the texture of cooked rice was investigated using hot-water soluble rice starch. The structure of hot-water soluble starch bound amylose which was composed of small molecular weight and amylopectin which was composed of chain length of $\overline{DP}\;10{\sim}20$, and the average composition of amylose : amylopectin was 7 : 3. The molecular weight of amylose was the smaller and super long chain of amylopectin was the fewer, the extractable ratio of hot-water soluble rice starch was the higher. And hot-water solubility of rice starch be responsible for molecular structure of starch. On the texture of cooked rice, the extractable ratio of hot-water soluble rice starch was the higher, the hardness was the lower and the adhesiveness was the higher. The results suggest that the molecular structure of rice starch could be responsible for the texture of cooked rice.

• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.613-617
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• 1988

This study was undertaken to observe the effects of partial replacement of acorn starch with dent, cross-linked, or acid modified corn starches, and of refrigeration on sensory characteristics of acorn mooks(starch gels). Triangle test was used to determine if there were noticeable differences among the monks. In order to find the source of differences, various sensory properties of the monks were evaluated with quantitative descriptive analysis on unstructured scale. The results indicated that added corn starches affected significantly most of the sensory characteristics evaluated. Control acorn monks had greater intensities in color, clarity, bend property, firmness and cohesiveness. Monks containing cross-liked corn starch were more similar to control than the other mixed starch monks, fresh or refrigerated.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.210-216
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• 2002

Air abrasion technology can prepare enamel and dentin for bonding, similar to etching by acidic gels and solutions. Longer treatment can excavate pit and fissures, preparing the tooth for immediate placement of bonded resin materials. Although not appropriate for every clinical situation, the air abrasive technology minimizes heat, vibration and bone-conducted noise associated with conventional means of caries removal since the cutting is accomplished by air pressure. Also, patients treated with the air-abrasion technology rarely request anesthesia. Air abrasion technology was more effective in treating early carious lesions and stains compared to lesions where caries had already progressed to produce soft dentin and the strong air stream and noise caused by the evacuation system was a major discomfort to pediatric patients, and the experience and skillfulness of clinician should be required for accurate and proper tooth preparation.