• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권3호
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• pp.238-244
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• 2000

The present study was aimed to investigate the effect of osseointegration according to implant placement timing in the distracted alveolar bone using intraoral distraction device. Six adult mongrel dogs of either sex, weighing about 15kg, were used. The animals were divided into 4-week and 8-week groups according to the timing of implant installation. The left upper and lower premolars and first molars were extracted and an alveoloplasty was performed to simulate an atrophic ridge. After 12 weeks of healing, a segmental osteotomy was made and an intraoral distraction device which was designed for augmentation of vertical height of the edentulous ridge was applied. Latency period was allowed for 5 days and then distraction was made at a rate of 1.2mm/day for 8 days. Four or eight weeks after distraction, implants were installed. Twelve weeks after implant installation, the animals were sacrificed. Macroscopic, radiographic, and histologic examinations of distracted alveolar ridge were performed. No significant abnormalities such as infection and dehiscence of overlying soft tissue were observed. Radiographically, there was slight bone resorption around the medial and distal edges of the alveolar bone segment, and a new bone deposition was observed in the neighboring alveolar crest area in the both groups. The satisfactory osseointegration was achieved in the distracted gap of the both groups, but fibrous tissue appeared on the buccal side of implant in the distracted gap in 4-week group. These results suggest that proper timing of implant installation is 8 weeks rather than 4 weeks after distraction when dental implant is to be placed onto the distracted bone.

• 한국지반신소재학회논문집
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• 제10권2호
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• pp.13-19
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• 2011

PC 암거는 터파기, 하부지반 처리, 암거 거치, 상호접합면에 누수방지용 패킹재 부착, PS 강선의 긴장을 통한 상호박스 접합, 되메우기 등의 일련의 과정으로 시공되어진다. 이 때 부적절한 하부지반 처리는 박스간 상호 부등침하를 야기할 수 있으며 결과적으로 지하수의 와류 및 내부유수의 누수를 발생시키게 된다. 본 연구에서는 하부지반이 연약한 경우 PC 암거 접합부의 부등침하를 저감하기 위하여 개발된 PC 기초판과 일체화된 암거의 거동을 현장 시험시공을 통해 분석하였다. 암거의 거동은 접합부에서 암거간의 벌어짐, 하부지반에 작용하는 토압 증가량, 암거 상부의 침하량 계측을 통해 분석되었으며, 분석결과로부터 PC 기초판과 일체화된 암거가 일반적인 시공방법인 PS 강선의 인장으로 체결된 암거에 비하여 침하 및 접합부에서 벌어짐이 적게 발생하는 것으로 나타났다.

• 한국지반공학회논문집
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• 제19권6호
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• pp.379-385
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• 2003

기존의 섬유보강성토제체의 설계에서 보강재의 변형을 고려하지 않고 연직응력을 보강재의 인장강도로 사용함으로써, 흙구조물의 파괴응력에 대응하는 보강재의 한계응력산정과 그에 따른 보강재의 규격결정이 불가능했다. 보강재에 의해 보강된 성토제체의 파괴면에서 보강재와 흙의 거동은 초기응력단계에서는 일체로서 거동하지만 응력의 증가에 따라 변형량의 차이가 증가한다. 이러한 문제는 흙구조물의 보강재설계에서 중요한 요소로서 보강효과에 큰 영향을 미칠 수 있다. 본 연구에서는 연약지반위에 PET Mat로 보강한 성토제체의 보강재 설계 시 파괴면상의 보강재 설치위치에서 흙과 보강재의 변형량을 고려한 설계방법을 제시하였다. 연구결과에 의하면, 허용안전율을 확보하는 범위내에서 예상파괴면상의 보강재 설치위치에서의 보강재의 인장강도는 흙의 응력 이상이어야 하며, 흙의 변형링${\Delta S}$과 보강재의 변형량${\Delta G}$이 일체로 거동하는 보강재의 소요인장강도를 보강재의 설계인장강도로서 결정하는 것이 합리적이고 경제적인 것으로 평가되었다.

• 전기학회논문지
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• 제66권4호
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• pp.659-665
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• 2017

Power semiconductor devices required the low on-resistance and high breakdown voltage. Wide band-gap materials opened a new technology of the power devices which promised a thin drift layer at an identical breakdown voltage. The diamond had the wide band-gap of 5.5 eV which induced the low power loss, high breakdown capability, low intrinsic carrier generation, and high operation temperature. We investigated the p-type pseudo-vertical diamond Schottky barrier diodes using a numerical simulation. The impact ionization rate was material to calculating the breakdown voltage. We revised the impact ionization rate of the diamond for adjusting the parallel-plane breakdown field at 10 MV/cm. Effects of the field plate on the breakdown voltage was also analyzed. A conventional diamond Schottky barrier diode without field plate exhibited the high forward current of 0.52 A/mm and low on-resistance of $1.71{\Omega}-mm$ at the forward voltage of 2 V. The simulated breakdown field of the conventional device was 13.3 MV/cm. The breakdown voltage of the conventional device and proposed devices with the $SiO_2$ passivation layer, anode field plate (AFP), and cathode field plate (CFP) was 680, 810, 810, and 1020 V, respectively. The AFP cannot alleviate the concentration of the electric field at the cathode edge. The CFP increased the breakdown voltage with evidences of the electric field and potential. However, we should consider the dielectric breakdown because the ideal breakdown field of the diamond is higher than that of the $SiO_2$, which is widely used as the passivation layer. The real breakdown voltage of the device with CFP decreased from 1020 to 565 V due to the dielectric breakdown.

• 복식문화연구
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• 제16권6호
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• pp.1035-1049
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• 2008

The purpose of this study was specifically focused on the lower garment sizing system of adolescent apparel, especially on trousers for adolescent boys. Research Method was performed by using the physical measurements of adolescent boys ($14\sim19$ years old, n=1,344) based on the 'he fifth Korean national physical standard reports' surveyed by SIZEKOREA. The basic materials for this study are obtained from the observations of physical characteristics and classification of physical figures based on the characteristics from waist down. The results from this study are as follows. 1) according to the analyses of physical changes, most items including height, circumference, length, breadth and depth were increased at the age of $14\sim18$ and gradually reduced at the age of 19. 2) The factors which compose the lower body resulted were appeared that the first factor was vertical factor, the second factor was horizontal factor, the third factor was hip length, and the last factor was buttlock-popliteal length. 3) Formalization of physical figures for adolescent boy's lower body analyzed from factors grouped three types. 4) The basic parts that we used to propose the apparel sizing system distinguished by physical figures were Waist Circumference (Omphalion) (every 3cm regular gap) and Hip Circumference (irregular gap). Physical figures assigned 5 to Type T, and 4 to type M. The reference measurement items were divided into 7 items which are correlated with apparel manufacture.

• 한국전산구조공학회논문집
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• 제30권4호
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• pp.363-370
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• 2017

본 논문에서는 원통형 혼합기를 대상으로 블레이드의 각도, 길이, 개수 및 블레이드와 탱크 바닥과의 간극을 설계변수로 선정하고, 각각의 설계변수가 혼합성능에 미치는 영향을 분석하였다. 이산요소법을 이용하여 임펠러 회전에 의한 고체 입자의 혼합공정을 해석하였으며, 혼합지수를 도입하여 혼합성능을 정량적으로 평가하였다. 다양한 설계변수의 조합을 고려한 실험계획법으로 설계변수의 주효과와 교호작용을 분석함으로써, 블레이드 각도가 입자의 혼합성능에 가장 지배적인 영향을 미치며 간극의 영향은 상대적으로 작다는 결론을 도출할 수 있었다. 또한 가장 우수한 혼합성능을 보이는 설계변수의 조합을 제시하였다.

• Transactions on Electrical and Electronic Materials
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• 제7권4호
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• pp.196-203
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• 2006

An air-gap type FBAR was designed using Leach equivalent model for analyzing a vertical structure of the FBAR. For the top electrode, Pt, and the bottom electrode, Au, of $1.2{\mu}m$ thickness and the piezoelectric of 0.8,urn thickness, the resonance and anti-resonance occurred at 2.401 GHz and 2.460 GHz, respectively. $S_{11}$ was increased and $S_{21}$ was decreased as the resonance area of FBAR was widened. We observed the characteristics of insertion loss, bandwidth and out-of-band rejection of ladder-type FBAR BPF by changing resonance areas of series and shunt resonators and by adding stages. As the resonance area of series resonator was increased, insertion loss was improved but out-of-band rejection was degraded. And as the resonance area of shunt resonator was increased, insertion loss was degraded a little but out-of-band rejection was improved even without adding stages. We, also, changed the shape of the resonance area from square shape to rectangle shape to examine the effects of the resonator shape on the characteristics of the BPF. The best performances were observed when the sizes of series and shunt resonator are $150{\mu}m{\times}l50{\mu}m\;and\;5{\mu}m{\times}50{\mu}m$, respectively. Out-of-band rejection was improved about 10dB and bandwidth was broadened from 30MHz to 100MHz utilizing inductor tuning on $2{\times}2\;and\; 4{\times}2$ ladder-type BPFs.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권6호
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• pp.367-374
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• 2000

This paper presents a method to fabricate freestanding structures by (100) silicon anisotropic etching and nickel electroless plating. The electroless plating process is simpler than the electroplating, and provides good coating uniformity and improved mechanical properties. Furthermore, the (100) silicon anisotropic etching in KOH solution with being aligned to <100> direction provides vertical (100) sidewalls on etched (100) surface. In this paper, the effects of the nickel electroless plating condition on the properties of electroless plated metal structures are investigated to apply fabrication of micro structures and then various micro structures are fabricated by nickel electroless plating. And then, the structures are released by silicon anisotropic etching in KOH solution with a large gap between the structure and the substrate. The fabricated cantilever structures are $210\mum$. wide, $5\mum$. thick and $15\mum$. over the silicon substrate, and the comb structure has the comb electrodes which are $4\mum$. wide and $4.3\mum$. thick separated by$1\mum$. It is released by silicon anisotropic etching in KOH solution. The gap between the structure and the substrate is $2.5\mum$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.210-211
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• 2007

Amid booming PV(photovoltaic) industry, BIPV(Building Integrated PV) is one of the best fascinating PV application technologies. To apply PV in building, variable factors should be reflected such as installation position, shading, temperature effect and so on. Especially a temperature should be considered, for it affects both electrical efficiency of PV module and heating and cooling load in building. Transparent PV modules were designed as finished material for spandrels are presented in this paper. The temperature variation of the modules with and without air gap and insulation were compared and analyzed. The results showed that the module with air gap and insulation has a much larger temperature variation than another transparent module. The temperature of the module reached by 55degree C under vertical irradiance of lower 500$W/m^2$. And the temperature difference between these modules was about 15degree C. To analyze the output performance of module according to temperature variation, separate module was manufactured and measured by sun-simulator. The results showed that 1 degree temperature rise reduced about 0.45% of output power.

• 농촌계획
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• 제22권3호
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• pp.107-118
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• 2016

In order to ensure revenue of agricultural products which have encountered the dramatic decline of prices in distribution, the export of the domestic farm produce was started and it has been considered to play the significant role to make fundamentals for securing the stable revenue of farms and future of agricultural industries. The Korean government has endeavored to increase scale and volume of export and make the stable structure for export transaction by supporting government policies. Since the export of the agricultural products was influenced by multiple and uncertain factors such as the gap of GDP, distance, the difference of climatess between countries, in this study of agricultural exports, the attributes of export according to changed factors are derived by using RCA and gravity model. As the complexity of export environment has been increased compared to the past, it is necessary to analyze the attributes of agricultural exports. In this study, by using network theory, trade network of agricultural product, the periodic changes of relations, the changes of centrality and maxium flow are derived. Even though the trade quantity of existing agricultural fresh products are still small, the study derived the need to vertical integration for expanding agricultural product export by applying network theory.