• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.362-365
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• 2005

Currently Chemical Mechanical Planarization (CMP) has become an essential step in the overall semiconductor wafer fabrication technology. Especially the CMP pad conditioner, one of the diamond tools, is required to have strong diamond retention. Strong cohesion between diamond grits and metal matrix prevents macro scratch on the wafer. If diamond retention is weak, the diamond will be pulled out of metal matrix. The pulled diamond grits are causative of macro scratch on wafer during CMP process. Firstly, some results will be reported of cohesion between diamond grits and metal matrix on the diamond tools prepared by three different manufacturing methods. A measuring instrument with sharp cemented carbide connected with a push-pull gauge was manufactured to measure the cohesion between diamond grits and metal matrix. The retention force of brazed diamond tool was stronger than the others. The retention force was also increased in proportion to the contact area of diamond grits and metal matrix. The brazed diamond tool has a strong chemical combination of the interlayer composed of chrome in metal matrix and carbon which enhance the interfacial cohesion strength between diamond grits and metal matrix. Secondly, we measured real-time data of the coefficient of friction and the pad wear rate by using CMP tester (CETR, CP-4). CMP pad conditioner samples were manufactured by brazed, electro-plated and sintered methods. The coefficient of friction and the pad wear rate were shown differently according to the arranged diamond patterns. Consequently, the coefficient of friction is increased according as the space between diamonds is increased or the concentration of diamonds is decreased. The pad wear rate is increased according as the degree of diamond protrusion is increased.

• 대한치과교정학회지
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• 제40권3호
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• pp.176-183
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• 2010

고정식 교정장치를 이용한 교정치료 후 교합의 기능적 변화를 평가하기 위해, 교합력 및 교합접촉면적을 측정하여 단기적인 변화 양상을 확인하고 소구치 발치 여부에 따른 차이를 파악하였다. 고정식 교정장치로 치료를 종료한 18세 에서40세 사이의 성인을 남자군과 여자군으로 분류하고, 각각의 군을 4개의 소구치를 발치한 군과 비발치로 치료한 군으로 세부 분류하였다(남자발치군 16명, 남자비발치군 18명, 여자발치군 19명, 여자비발치군 21명). Dental prescalesystem (Fuji Film Corp., Tokyo, Japan)의 pressure sensitive sheet를 5초간 최대교두감합위에서 최대근력으로 교합하도록 한 뒤 CCD camera를 이용해 교합력과 교합면적을 측정하였다. 고정식 교정장치를 제거하고 고정식유지장치를 붙인 직후, 교정장치 제거 1주일, 1개월, 3개월, 6개월, 1년 뒤에 각각 측정하여 비교하였다. 모든 군에서 교정장치 제거 후 1년간의 유지기간 동안 교합력과 교합면적은 점진적으로 증가하였다 (p < 0.05). 모든 측정 시기에서 남자군은 여자군보다 높은 교합력과 교합면적을 보였으며 (p < 0.05), 남자, 여자군 모두에서 발치군과 비발치군 사이에는 교합력 및 교합면적에서 통계적으로 유의한 차이가 관찰되지 않았다 (p > 0.05). 본 연구를 통해 교정치료 후 1년간의 유지기간 동안 교합이 기능적으로 향상됨을 파악하였고, 소구치 발치로 인한 교합의 기능적 저하는 없을 것이라 추측할 수 있었다.

• 대한치과의사협회지
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• 제15권11호
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• pp.763-766
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• 1977

The Purpose of this study was to observe force required to remove some kinds of pin from dentin. The teeth were embedded within a resin cylinder and the occlusal surface was sectioned at a right angle to the axis of the cylinder to expose dentin surface. Thread mate system pin (minim and regular), friction Iocked pin and cemented pin were tested Pin holes were drilled by handpiece and depths of pin holes were tested 1,2 and 3mm. After insertion of the pins into pinhole, tensile loading was performed on the Instron testing machine at the speed of 0.5 inch/min. Results were follewed: 1. In retention, the cemented pins are the least, the friction locked pins intermediate and the self threading pins the greatest in all pins. In self threading pins, regalar pin has greater retention than minim pin 2. The deeper the depth of the pin hole is, the more the retention of the pin increases.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1173-1176
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• 2004

In a previous work we reported the bistable property by doping a chiral material in a splay cell. The bistable states are the splay state and the metastable 180$^{\circ}$twist state. The retention time of the metastable state can be changed by the variation of d/p (cell gap over pitch), cell gap, pretilt angle, azimuthal anchoring force, liquid crystal material, and so on. In this paper we will present uniform bend transition and twist retention time improvement in a multi-domain BCSN LC cell by using the multi cell gap method.

• 한국수산과학회지
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• 제50권3호
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• pp.250-256
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• 2017

This study investigated the removal efficiency of organic matter and nitrogen from fish farm effluent by hydraulic retention time (HRT) using an upflow biological filter (ANR system) reactor. The recycling time and influent flow in the reactor were controlled to 14.8, 7.4, 5.5 and 3.2 h to evaluate HRT. In addition, each reactor was coupled to a fixed bed upflow filter charged with media. The results showed that removal efficiency was ${\geq}95%%$ with an HRT of 5.5 h, and nitrification efficiency was reduced to 81% with an HRT of 3.2 h, although nitrification efficiency temporarily decreased due to the shock load as HRT decreased. Total nitrogen removal rate was also reduced to about 65% with an HRT of 3.2 h, which was considered a washout effect of nitrifying and denitrifying microorganisms by increasing the shearing force to the filter media, which decreased organic matter and nitrogen removal efficiency.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.293-300
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• 2004

A new earth retention system(Innovative Prestressed Wale System) has been developed and introduced. IPR earth retention system provides an economical benefit, construction easiness, good performance and safety. IPS is a prestressed wale by using a steel wire, which provides a high stiffness to resist the earth pressure. In order to investigate the applicability and the safety of new IPS system, field tests were performed. A new IPS system applied in a trench excavation performed successfully. Basic principles and mechanism of IPS system and measure performance were presented and discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2406-2409
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• 2008

The concept of optical mobility in the optical particle separation was derived. To verify the concept of the optical mobility, three particles were chosen to test the effects of optical mobility, namely, PSL, PMMA and silica particles. Three different experiments were performed. Firstly, retention distances of the different sized particles were measured and predicted. Secondly, retention distances of particles, having same size but different refractive indices, were measured and predicted. Finally, retention distances of the particles, which had the same optical mobility but very different sized and refractive indices, were measured and predicted.

• 한국지반공학회논문집
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• 제23권7호
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• pp.27-36
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• 2007

프리스트레스트 띠장을 적용한 흙막이 시스템의 안정성을 평가하고 거동 특성을 규명하기 위하여 모형 시험이 수행되었다. 본 흙막이 시스템의 모형 시험을 위해 현장 규모의 프리스트레스트 띠장을 적용한 흙막이 시스템에 대한 차원 해석이 수행되었다. 본 논문에는 새로운 흙막이 시스템에 대한 차원 해석의 절차 및 방법이 제시되어 있다. 차원 해석 결과로부터 모형 규모의 프리스트레스트 띠장을 적용한 흙막이 시스템을 구현하였다. 모형 시험 중 새로운 흙막이 시스템 부재에 대한 계측을 수행하여 흙막이 벽체 배면의 토압 거동, 프리스트레스트 띠장의 변형 거동, 띠장 시스템 부재의 힘 거동과 버팀보의 힘 거동을 파악하였다. 모형 시험 결과는 프리스트레스트 띠장 시스템 부재의 설계 결과와 비교 평가되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1261-1262
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• 2010

• Journal of Acupuncture Research
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• 제35권4호
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• pp.238-243
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• 2018

Background: Various factors can alter the efficacy of acupuncture treatment, such as the location of points, manipulations, depth of insertion, needle retention time, and needle type. In this study, the effect of needle diameter on the efficacy of acupuncture treatment was quantitatively evaluated. Methods: Five acupuncture needles of different diameters used in clinical practice were compared. Force on the porcine tissue phantom was measured using a sensor. Lifting-thrusting and twisting-rotating movements were performed using a needle insertion-measurement system. After repeated measurements, force magnitude was calculated and compared. Following this, we correlated needle diameter and force magnitude during lifting-thrusting and twisting-rotating movements. Results: The force magnitude was significantly altered between needle diameters during lifting-thrusting movements, as shown by a significant positive correlation between needle diameter and force magnitude. In contrast, there was no difference in force magnitude with different needle diameters during twisting-rotating movements. Conclusion: Needle diameter can significantly affect stimuli and force magnitude dependent upon the type of manipulation. Research into the effect of other needle type characteristics and stimulation method is necessary to fully elucidate the role of acupuncture needle choice in treatment efficacy.