• 구강회복응용과학지
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• 제26권4호
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• pp.455-462
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• 2010

치아의 마모를 보이는 환자가 진료실을 찾는 이유는 보통 심미적인 이유, 기능적인 이유, 지각 과민증의 증가 때문이다. 이때 먼저 병인 요소들의 조절이 필요하고, 환자의 나이가 고려되어야 한다. 전반적인 치아 마모를 보이는 환자의 치료를 위하여 때때로 전악을 보철로 수복해야 할 경우가 있고, 이때에는 보철물의 공간 확보를 위한 교합거상이 필요하다. 전악 수복을 할 때 장기적인 좋은 결과를 얻기 위해서는 정확한 진단, 적절한 수직고경 확립, 최적의 수복재료 선정을 바탕으로 지속적인 교합조정 및 구강 위생 관리가 필수적이다. 본 증례에서는 과도한 마모를 보여 심미적인 이유로 병원을 찾아온 환자로, 보철수복 공간을 위하여 교합고경을 증가시켜 중심위를 이용하여 수복한 치험례를 문헌고찰과 함께 보고하고자 한다.

• 대한가정학회지
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• 제37권12호
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• pp.193-203
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• 1999

This study was executed to show influence of material and property of sportswear to physiological responses of body and comfort sensation and to supply basic research data about comfortable sportswear Trainning wear was manufactured with cotton(C) and hygroscopically treated polyester material (FP), and its properties of material were measured. Then rectal temperature, skin temperature, heart rate, weight loss, clothing microclimate and subjective sensation was estimated with study of wearing with these sportswear and examined the influence that it got to physiological responses of body and sensation. Health adult men were selected for subjects and executed at climatic chamber of temperature, $20\pm2^{\circ}C and humidity, $60\pm5%$ R.H. Conclusively sportswear of hygroscopically treated polyester is a favorable functional material. So far factor that affect to physiological comfort sensation has been explained mostly by moisture regain but in our experiment, it turned out that air permeability, water absorption velocity and dynamic oater absorption etc. were affecting factors. So according to this result, air permeability and moisture permeability should be considered with transmittance of temperature moisture for development of comfort material.

• 한국정밀공학회지
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• 제33권8호
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• pp.661-668
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• 2016

Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.

• Elastomers and Composites
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• 제56권4호
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• pp.223-233
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• 2021

In this study, epoxidized liquid isoprene rubber (E-LqIR) was used as a processing aid in a silica-filled natural rubber compound to improve the fuel efficiency, abrasion resistance, and oil migration problems of truck and bus radial tire tread. The wear resistance, fuel efficiency, and extraction resistance of the compound were evaluated according to the molecular weight of E-LqIR. Results of the evaluation showed that the E-LqIR compound had a lower chemical crosslink density than that of a treated distillate aromatic extract (TDAE) oil compound because of the sulfur consumption of E-LqIR. However, the filler-rubber interaction improved because of the reaction of E-LqIR with silica and crosslink with the base rubber by sulfur. As the molecular weight of E-LqIR increased, crosslink with sulfur was facilitated, and the filler-rubber interaction improved, resulting in improved abrasion resistance. The fuel efficiency performance of the E-LqIR compound was poorer than that of the TDAE oil compound because of the low chemical crosslink density and hysteresis loss at the free chain end of E-LqIR. However, the fuel efficiency performance improved as the molecular weight of E-LqIR increased.

• 열처리공학회지
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• 제5권2호
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• pp.122-132
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• 1992

This study has been performed to investigate into some effects of the power density and traverse speed of laser beam on the optical microstructure, hardness and wear characteristics of medium carbon low alloy steel treated by laser surface hardening technique. The results obtained from the experiment are summarized as follows : (1) Optical micrograph has shown that finer lath martensite is formed and the amount of undissolved complex carbides increases as the traverse speed increases under the condition of a given power density, whereas the coarsening of lath martensite and the reduction of undissolved complex carbides occur with increasing the power density at a given traverse speed. (2) Hardness measurements have revealed that as the traverse speed increases, hardness values of outermost surface layer more of less decrease under low power densities, but are uniformly distributed under high power densities, also showing that they are uniformly distributed at low traverse speeds and more or less decrease at high traverse speeds with increasing the power density. (3) The effective case depth has been found to decrease from 0.26 mm to 0.17 mm with increasing the traverse speed from 1.5 m/min to 3.0 m/min at a given power density of $25.48{\times}10^3w/cm^2$ and to increase from 0.20 mm to 0.36 mm with increasing the power density from $19.11{\times}10^3w/cm^2$ to $38.22{\times}10^3w/cm^2$ at a given traverse speed of 2.0 m/min. (4) Wear test has exhibited that the amount of weight loss of laser surface hardened specimen with respect to sliding distance at a given load increases with increasing traverse speed at a given power density and decreses with increasing power density at a given traverse speed.

• 드라이브 ㆍ 컨트롤
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• 제11권2호
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• pp.30-35
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• 2014

The pumps of electro-hydrostatic actuators operate most frequently in boundary lubrication speed range, as they compensate for the position control errors as a control element. When conventional swash plate type piston pumps are applied to electro-hydrostatic actuators, the frictional power losses as well as the wear rate of sliding components, such as piston shoes can increase drastically under the boundary friction condition. In this paper, the power losses of the piston shoes were investigated which were engendered by a frictional solid-to-solid contact and leakage flow rate of their hydrostatic bearing. In order to reduce them, DLC-coating was applied to the swash plate and the ball joint of pistons along with its effects were demonstrated. In addition, it was also shown that the wear rate of the piston shoes could be markedly reduced using the DLC-coated swash plate.

• 대한치과보철학회지
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• 제59권2호
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• pp.210-219
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• 2021

치아의 과도한 마모는 저작 효율 감소, 교합평면 붕괴 및 안모 변화를 일으킬 수 있다. 수직고경 변화를 동반한 전악 수복의 경우 측두하악관절, 저작근 및 치아의 동통을 유발할 수 있으므로 정밀한 진단과 치료 계획이 요구된다. 본 증례는 69세 남성으로 구치부 지지가 상실된 상태로 과도한 치아 마모 증상을 보이는 상태였다. 가철성 교합안정장치 및 임시보철물로 증가된 수직고경의 적응 정도를 평가하였고, 임플란트를 동반한 지르코니아 고정성 보철물을 이용하여 최종 보철 수복을 진행하였다. 안정적인 전방유도 설정, 적절한 구치부의 이개, 중심위에서 균등한 치아 접촉을 부여하여 기능 및 심미적으로 만족스러운 치료 결과를 보였기에 보고하고자 한다.

• Tribology and Lubricants
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• 제35권1호
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• pp.1-8
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• 2019

Demand for plastic gears are increasing in many industries due to their low production cost, light weight, applicability without lubricant, corrosion resistance and high resilience. Despite these benefits, utilizing plastic gears is limited due to their poor material properties. In this work, DLC coating was applied to improve the tribological properties of polyamide66 gear. 0 V, 40 V, and 70 V of negative bias voltages were selected as a deposition parameter in DC magnetron sputtering system. Pin-on-disk experiment was performed in order to investigate the wear characteristics of the gears. The results of the pin-on-disk experiment showed that DLC coated polyamide66 with 40 V of negative bias voltage had the lowest friction coefficient value (0.134) and DLC coated PA66 with 0 V of negative bias voltage showed the best wear resistance ($9.83{\times}10^{-10}mm^3/N{\cdot}mm$) among all the specimens. Based on these results, durability tests were conducted for DLC coated polyamide66 gears with 0 V of negative bias voltage. The tests showed that the temperature of the uncoated polyamide66 gear increased to about $37^{\circ}C$ while the DLC coated gear saturated at about $25^{\circ}C$. Also, the power transmission efficiency of the DLC coated gear increased by about 6% compared to those without coating. Weight loss of the polyamide66 gears were reduced by about 73%.

• 대한치과보철학회지
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• 제57권3호
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• pp.280-287
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• 2019

구강이라는 특수한 환경 속에서 치아는 평생을 거쳐 마모, 부식 등을 겪게 된다. 점진적이며 일정한 치아의 마모는 노화의 자연스러운 현상이나, 특정 요소에 의한 마모나 부식 등은 병적인 요소이며 교합면의 병리적 손상과 이에 따른 교합 부조화, 심미적 문제, 턱관절 장애 등을 야기할 수 있다. 본 증례는 26세의 젊은 여성 환자로 전반적인 치아의 마모와 부식이 동반된 상태였다. 디지털 안모 분석, 생리적 안정위, 전치부 치관 길이 평가 등을 통해 진단 납형을 제작하였다. 디지털 분석을 통해 치관연장술에 필요한 가이드를 제작하여 수술을 진행하였고 임시 보철물을 통하여 저작 기능 및 심미성을 회복하였다. 지르코니아 최종 보철로 수복하여 심미적, 기능적으로 만족할만한 결과를 얻었으므로 이 증례를 보고하고자 한다.

• 구강회복응용과학지
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• 제39권4호
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• pp.222-228
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• 2023

교모는 치아 간의 접촉으로 인하여 치아 경조직이 소실되는 것으로, 심한 경우 상아질이 노출되어 선택적인 부식과 치아의 과도한 마모가 동반되는데, 이를 cupping이라고 부른다. 이러한 병소를 치료하지 않고 방치할 경우 병소의 크기가 점차 커지게 되어 지지되지 않는 법랑질이 파절되고, 결과적으로 심미성과 저작 기능이 저하된다. 본 증례보고에서는 심한 교모로 인해 cupping과 법랑질 파절이 동반된 환자에서 유기필러가 함유되어 부드러운 성질을 지닌 레진을 이용하여 직접수복을 실시하였다. 6년 후의 경과관찰에서 교합면의 충전은 대부분 탈락하였으나 협측의 충전은 비교적 온전하게 남아 있음을 관찰할 수 있었고, 이런 형태의 레진이 교합력이 크게 가해지는 부위보다는 교합력이 비교적 약하게 가해지는 부위에 적합한 재료임을 확인할 수 있었다.