• Maxillofacial Plastic and Reconstructive Surgery
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• 제15권2호
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• pp.123-128
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• 1993

For the purpose of studying postsurgical stability of mandibular prognathism, 18 patients(8 men and 10 women) were selected who underwent sagittal split ramus osteotomy and lateral cephalograms taken preoperatively, immediate postoperatively, and over 6-month follow-up were traced and analysed. The following results were obtained. 1. Average magnitude of setback vas 11.0mm, and aberage relapse was 3.0mm, so the rate of relapse was 27%. 2. Magnitude of mandibular setback contributed to relapse. 3. The patients of less than 10mm setback showed average 10% of relapse rate, and it was of little clinical significance. 4. Proper detachment of pterygomasseteric sling prevention of clockwise rotation of proximal segment and rigid fixation are recommended for the better postoperative stability.

• 한국자동차공학회논문집
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• 제8권4호
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• pp.1-9
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• 2000

To understand the thermal characteristics around the piston ring gap ring gap positions and piston temperatures are measured simultaneously. The locations of piston ring gap are measured by the radio-tracer method and piston temperature are measured by a K-type thermocouple and scissors type linkage system. From these experiments following facts are clarified. Piston temperatures fluctuate according to the piston ring rotation. And the temperature fluctuation is mainly affected by top ring gap position irrelevant to the second ring fop position. If the top ring gap position increases and the temperature of top ring groove shows maximum value when top rin gap position coincide with temperature measuring point. The maximum amplitude of temperature fluctuation which is proportional to the blow by gas rate is around 12-15$^{\circ}C$.

• 천문학회보
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• 제38권2호
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• pp.61.1-61.1
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• 2013

Turbulence is a common phenomenon in astrophysical fluids such as the interstellar medium (ISM) and the intracluster medium (ICM). In turbulence studies it is customary to assume that fluid powered by an energy injection on a single scale. However, in astrophysical fluids, there can be many different driving mechanisms that act on different scales simultaneously. In this work, we assume multiple energy injection scale (2${\surd}$12 and 15

• 한국생산제조학회지
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• 제22권1호
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• pp.107-111
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• 2013

The gyroscopes have been used as a suitable inertial instrument for the navigation guidance and attitude controls. The accuracy as very sensitive sensor is limited by the lock-in region (dead band) due to the frequency coupling between two counter-propagating waves at low rotation rates. This frequency coupling gives no phase difference, and an angular increment is not detected. This problem can be overcome by mechanically dithering the gyroscope. This paper presents the design method of mechanical dither by the theoretical considerations and the verification of the theoretical equations through FEM applications. As a result, comparing to the past result, the maximum prediction error of resonant frequency was within 3 percent and peak dither rate was within 5 percent. It was found that the theoretical equations can be feasible for the mechanical performance of dither.

• 한국결정학회지
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• 제4권1호
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• pp.42-48
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• 1993

K6P4Ol3 응제를 사용하여 TSSG법에 의해 KTP(K Tiop04) 단결정을 성장시켰다. 가열로의 내부에 heatpipe와 복사방열판을 설치하여 도가니 내의 온도 안정성 및 균일도를 향상시켰다. 크고 양질의 단결정을 얻기 위한 목적으로 조업온도 구간,초기 냉각속도, 강제교반, 융제의 재사용과 같은 몇 가지 조업변수들에 따른 영향을 비교 고찰하였다. 본 융제의 조건하에서(0.6g KTP/lg flux), 초기 냉각속도가 0.1℃/hr 이하까지 느릴수록, 적절한 결정 회전이 수반될수록 양질의 단결정성장에 유리하였다. 최대 44 × 39 ×17체 크기의 KTP단결정을 얻을 수 있었으며, 단순가공 상태하에서도 21.3% SHG 변환효율을 나타내었다.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.1949-1954
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• 2010

자이로스콥은 네비게이션을 가이드하거나 특성을 제어하는데 적절한 관성 측정도구로 사용되었다. 매우 민감 한 센서로서의 정확성은 저회전율 역전파 사이의 진동수 커플링으로 인한 폐쇄영역(데드 밴드)으로 결정된다. 이 진동 커플링은 위상차가 없으며, 각증분 값은 검출되지 않는다. 이 문제는 자이로스콥의 기계적인 진동으로 해결될 수 있다. 본 논문은 FEM을 통해 이론적 식들의 이론적 고려사항과 증명의 방법으로 기계 진동의 설계방법을 제시한 것 이다. 결과적으로, 공명 진동수와 최대 진동률의 최대 예측 오차는 5 %이하였다. 진동의 기계적 성능을 위한 이론식 들은 타당하다고 할 수 있다.

• 한국잡초학회지
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• 제17권1호
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• pp.124-134
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• 1997

As control of plant diseases, insects and weeds were heavily relied on pesticides, residues of pesticides in environment and food supply were recently focused by environmentalists and consumer groups. The reduction of pesticide use was implemented in Sweden, Denmark, Netherland, England, and United States. Therefore, it is very important to discuss environmentally sound systems of weed management including cultural, mechanical, and integrated weed control. Mechanical methods using tillage, cultivation, mulching, burning, mowing, solarization, and UHF are used as one of most effective environmentally sound weed management systems. Cultural practices favoring the crops are excellent weed management measures. Correct seedbed preparation for the soil and cultural system, and use competitive cultivars contribute to weed management. Increasing crop density by higher seeding rate or by narrowing row width and careful attention to optimum fertility to produce vigorous crop plants increase competitiveness of crops against weeds. Crop rotation breaks life cycles of weeds by alternating the crop it must associate with. Herbicides are efficient and profitable to control weeds, but must be part of a total weed management program with use of minimum rate. The best weed management will be an integrated approach including two or more methods to manage weed problems.

• 한국ITS학회 논문지
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• 제19권1호
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• pp.121-131
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• 2020

현재의 교통정보는 루프검지기나 영상검지기를 통해 수집된다. 이러한 방법은 날씨와 시간에 영향을 많이 받기 때문에 이를 대체할 교통정보 생성 시스템이 필요하다. 이러한 문제점을 해결할 수 있는 기술로 무선 네트워크를 이용한 교통정보생성 시스템이 연구 단계에 있다. 차량 내의 스마트폰을 이용하여 교통정보를 생성하는 시스템에 대해 제안하고 필드 테스트를 통해 얻어진 수집율과 통행시간 오차율을 통해 제안방법의 성능을 검증하였다. 또한 회전방향별 교차로 통행정보를 생성하는 알고리즘에 대해 제안하고 이러한 유효정보의 양을 증가 시키는 방안에 대해 제시하고 결과를 확인한다.

• 한국환경보건학회지
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• 제21권4호
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• pp.49-55
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• 1995

Dyes are released into the environment as industrial wasterwater. Dyes are considered to be a pollution problem because of the wide spread into environment with a variety of colors. Continuous biodegradation of reactive dyes such as Rifacion Red H-3EB, Rifazol Blue BT, Rifacion Yellow P4G and Rifacion Brown RT were demonstrated using multistage rotating disc contactor immobilized by Aspergillus sojae B-10. Aspergillus sojae B-10 was cultivated the optimal medium containing 2.0% glucose, 0.08% $NaNO_3$, 0.1% $KH_2PO_4$ and 0.5% $MgSO_4\cdot 7H_2O$, pH 5 at 32$\circ$C. Mycelium of Aspergillus sojae B-10 were guck to the rotating disc for 10 days until steady state. For continuous biodegradation of reactive dyes by using rotating disc contactor, it was most effective biodegradation in the medium containing 1,000 ppm each dyes at the medium feeding rate of 20 ml per hour. Under the conditions biodegradation of each dyes on 2, 4 and 6 days were 20~50%, 75% and 96%, respectively. Therefore, practical application of reactive dyes were carried out at the feeding rate of 20 ml/h as synthetic wasterwater containing 500 ppm of mixture reactive dyes. It was found the highest levels of 94% biodegradation during 20 days.

• 한국전산유체공학회지
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• 제21권1호
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• pp.58-63
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• 2016

This research is to investigate the performance analysis for efficient design with four different inlet angles of the centrifugal pump impeller. Assuming that the rotation speed and exit angle are fixed, Four cases of the centrifugal pumps were numerically analyzed using ANSYS FLUENT. According to the numerical results, head and pump efficiency at inlet angle of 20 degrees was highest. There is no big difference of efficiency at inlet angle of 20 degrees compared to the inlet angle 30 degrees. About 15% of efficiency at inlet angle of 20 degrees is higher than inlet angle of 40 degrees and 31% higher than inlet angle oof 50 degrees. Because there is liner functional relationship between speed and flow rate, suction flow rate at inlet angle of 20 degrees is superior to the inlet angle of 30 degrees as much as 0.89%, inlet angle of 40 degrees as 13%, inlet angle of 50 as 28.4%. Head at inlet angle of 20 degrees is superior to the inlet angle of 30 degrees as much as 0.4%, inlet angle of 40 degrees as 2.7%, inlet angle of 50 degrees as 3.2%. There should exist highest efficiency and also optimal design shape at inlet angle of 20 degrees.