• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.738-747
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• 2006

The friction behaviour of Si-wafer, diamond-like carbon (DLC) and two self-assembled monolayers (SAMs) namely dimethyldichlorosilane (DMDC) and diphenyl-dichlorosilane (DPDC) coated on Si-wafer was studied under loading conditions in milli-newton (mN) range. Experiments were performed using a ball-on-flat type reciprocating micro-tribo tester. Glass balls with various radii 0.25 mm, 0.5 mm and 1 mm were used. The applied normal load was in the range of 1.5 mN to 4.8 mN. Results showed that the friction increased with the applied normal load in the case of all the test materials. It was also observed that friction was affected by the ball size. Friction increased with the increase in the ball size in the case of Si-wafer. The SAMs also showed a similar trend, but had lower values of friction than those of Si-wafer In-terestingly, for DLC it was observed that friction decreased with the increase in the ball size. This distinct difference in the behavior of friction in DLC was attributed to the difference in the operating mechanism. It was observed that Si-wafer and DLC exhibited wear, whereas wear was absent in the SAMs. Observations showed that solid-solid adhesion was dominant in Si-wafer, while plowing in DLC. The wear in these two materials significantly Influenced their friction. In the case of SAMs their friction behaviour was largely influenced by the nature of their molecular chains.

• International Journal of Ocean System Engineering
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• 제2권2호
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• pp.106-115
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• 2012

In the present study, TiN and CrN films were coated by arc ion plating equipment onto aluminum alloy substrate, A2024. The film thickness was about 4.65 ${\mu}m$. TiN and CrN films were analyzed by X-ray diffraction and energy dispersive X-ray equipments. The Young's modulus and the micro-Vickers hardness of aluminum substrate were modified by the ceramic film coatings. The difference in Young's modulus between substrate and coating film would affect on the wear resistance. The critical load, Lc, was 75.8 N for TiN and 85.5 N for CrN. It indicated from the observation of optical micrographs for TiN and CrN films that lots of cracks widely propagated toward the both sides of scratch track in the early stage of MODE I. TiN film began to delaminate completely at MODE II stage. The substrate was finally glittered at MODE III stage. For CrN film, a few crack can be observed at MODE I stage. The delamination of film was not still occurred at MODE II and then was happened at MODE III. This agrees with critical load measurement which the adhesive strength was greater for CrN film than for TiN film. Consequently, it was difficult for CrN to delaminate because the adhesive strength was excellent against Al substrate. The wear process, which the film adheres and the ball transfers, could be enhanced because of the increase in loading. The wear weight of ball was less for CrN than for TiN. This means that the wear damage of ball was greater for TiN than for CrN film. It is also obvious that it was difficult to delaminate because the CrN coating film has high toughness. The coefficient of friction was less for CrN coating film than for TiN film.

• 대한금속재료학회지
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• 제46권2호
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• pp.80-87
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• 2008

Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.303-306
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• 2003

Indonesia is a tropical country having a temperature range of 25-35$^{\circ}C$ which can affect the skin and causes damages like aging. This aging process is due, at least, to free radical reactions. For this reason, many attempts had been done to find out creams containing natural antioxidant compound which have a potential of free radical scavenger. Kluwek, a fermented form of foot ball fruit or picung (Pangium edule.Reinw), had been proved to contain antioxidant compound in its methanol fraction oil to which antiaging cream was formulated. Stability evaluation was conducted for cream with Kluwek oil compared to base cream, including organoleptic (colour and odour), pH, viscosity, particle size, centrifugation test and flow characteristics either in room temperature (27$^{\circ}C$) or stress condition (4$^{\circ}C$ and 5$0^{\circ}C$) for 8 weeks continuously, and six times cycling test at 4$^{\circ}C$ and 5$0^{\circ}C$ every 24 hours. The results showed that cream with Kluwek oil and base cream were stable at temperature 27 and 4$^{\circ}C$, cycling test and centrifugation test, but not stable at 5$0^{\circ}C$. Free radical evaluation was done by Electron Spin Resonance and the result showed that cream with Kluwek oil had less free radicals compared to base cream.

• 산업융합연구
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• 제19권6호
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• pp.81-91
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• 2021

본 연구는 보수볼을 이용한 발목 근력 강화 운동과 테이핑이 엄지발가락가쪽휨증 환자의 정적과 동적 발바닥 압력에 어떠한 영향을 미치는지 알아보고자 실시하였다. 대상자는 엄지발가락가쪽휨증을 가지고 있는 20대 남녀 26명이며, 테이핑군(Taping group, TG; n=13)과 발목 강화 운동군 (Ankle strengthening group, ASG; n=13)으로 무작위로 배치하였고, 각 군은 총 4주에 걸쳐 해당 중재를 실시하였며, 중재 전과 후에 정적, 동적 발바닥 압력을 측정하였다. 집단 간 변화량의 차이를 알아보기 위해 독립 T검증을 실시하였고, 집단 내의 사전-사후값의 측정값 차이가 유의한지 알아보기 위해 대응표본 T검증을 실시하였다. 통계적 유의수준은 α= .05로 설정하였다. 발의 전체 체중에 대한 비율(Foot)은 왼쪽 발의 ASG가 TG에 비해 집단 내 변화량이 유의하게 감소하였고(p<.05), 발의 표면적(Surface area)에서는 오른쪽 발의 TG가 ASG에 비해 집단 내 변화량이 유의하게 증가하였다(p<.05). 발의 엎침 운동의 정도(MP/change ratio)는 오른발의 TG가 ASG에 비해 집단 내 변화량이 유의하게 감소하였고(p<.05), 발의 힘(Force)에서는 왼발의 TG가 ASG에 비해 집단 내 변화량이 유의하게 증가하였으며(p<.05), 집단 간의 변화에서는 TG의 변화량이 ASG의 변화량보다 유의한 차이가 나타났다(p<.05). 따라서 보수볼을 이용한 발목 강화 운동과 테이핑은 엄지발가락가쪽휨증을 가진 환자에게 효과적인 변화를 주기에는 부족하다고 할 수 있다.

• 한국입자에어로졸학회지
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• 제15권4호
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• pp.173-182
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• 2019

Since airborne viruses have been known to aggravate indoor air quality, studies on the development of anti-viral air filter increase recently. In this study, the pressure drop and anti-viral efficiency of TiO₂ coated ceramic ball filter were evaluated. After the filter being inserted into a commercial room air cleaner, chamber test with aerosolized bacteriophage MS2 was performed. The porosity of TiO₂ coated ceramic ball filter was 0.85, and pressure drop was about 13 Pa for 1 m/s of air velocity. The anti-viral efficiency was about 93% when the reaction time was 25 minutes in a 1 ㎥ chamber.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.25-31
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• 2014

This paper details application of a DLC(Diamond Like Carbon)-coating to the swash plate and the ball joint of pistons that make sliding contact with the piston shoes of an axial piston pump. This process, aimed to reduce the frictional and leakage power losses of the hydrostatic piston shoe bearings at the low speed range. At lower speeds than 100rpm, the positive effects of the DLC-coating on the power loss reduction of the hydrostatic piston shoe bearings could be confirmed. These effects resulted in little improvement in volumetric efficiency of the test pump, but the mechanical efficiency could be raised by up to 5% at 100rpm; here, the DLC-coated swash plate played a more dominant role than the DLC-coated ball joint.

• Tribology and Lubricants
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• 제6권2호
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• pp.68-75
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• 1990

The metal-dithiophosphates as lubricant additives for reducing friction and wear, increasing load-carrying capacity and a antioxidant are very important as new additives developed in these day. The synthetic results of Metal-DTPs were described. The wear test was conducted with 4-Ball machine and wear debris were analyzed by ferrography. The tribological performances of Metal-DTPs were compared with Zn-DTP.

• Tribology and Lubricants
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• 제5권1호
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• pp.57-63
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• 1989

The soluble Mo-DTP compounds as lubricant additives for reducing friction and wear, increasing loadcarrying capacity, and as antioxidants is very important as a new additive developed in these day. The method of the compounds are described and the composition is analyzed with $^{31}$P NMR spectrometer. The wear test is conducted with 4-ball machine and the debris are analyzed by ferrography. Also the tribological performance of Mo-DTP compounds are compared with Moly Van L and Zn-DTP.

• Journal of Animal Science and Technology
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• 제55권5호
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• pp.461-466
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• 2013

본 연구는 시중에서 유통 중인 완자제품의 품질특성을 비교하여 완자제품의 개발에 기초자료로 활용하고자 대형마트에서 시판되고 있는 5개의 제품을 회사별로 나누어 실시하였다. 완자제품의 일반성분 분석 결과 수분 함량은 53.92~63.45%, 단백질 함량은 24.36~27.00%, 지방 함량은 10.43~17.46%이었고, 회분 함량은 1.22~1.71%의 수준이었다. 품질특성에서 pH는 6.41~6.68의 범위였으며, 가열감량은 12.27~18.42% 수준이었다. 또한 제품 1개 당 무게는 11.72~27.68 g로 나타났다. 육색에서 명도는 52.69~74.98, 적색도에서도 2.45~6.09의 수준을 나타내었다. 완자제품의 조직 특성에서도 제품사이에 변이가 나타났는데, hardness는 T1이, cohesiveness는 T1과 T5가, chewiness는 T1에서 높은 수준을 나타내었다. 관능검사의 결과에서는 T1이 다른 처리구들에 비해 다즙성 짠맛, 풍미, 색깔, 외관 그리고 전체 기호도가 가장 높은 점수를 나타내었다. 이상의 결과에서 시중 완자제품들은 일반성분, 가열감량, 육색 및 조직특성에서 변이가 나타내었는데, 이는 원료 배합비, 첨가제 및 성형 크기의 차이에서 기인한 것으로 사료되었다.