In the modern society, the sports industry is becoming an important industry that plays an important role in cultural exchange and economic development between countries. Along with this, the size of sports equipment manufacturers is also increasing, and especially in the archery field, domestic companies occupy a high share in the global market. However, in the case of precision accessories, foreign products are imported and used. Among the precision archery accessories, the cushion plunger is subjected to repetitive loads, and the surface damage due to wear affects the accuracy of the archery, so fatigue and wear analysis taking this into account are required. In this paper, a friction simulation was performed to calculate the fatigue life and wear amount of the cushion plunger among the precision archery accessories, and the validity of the analysis model was evaluated by comparing the friction test results.

As product diversity increases and product life cycle gets shorter, lead time reduction and manufacturing cost saving of die & mold are getting important in machinery, automotive, and electronics industries. To develop a novel free-machining die & mold steel, we try to modify the chemical compositions of AISI P20 mold steel by adding boron, nitride, and sulfur. After making three types of mold steels which are base metal of AISI P20 mod., boron and nitrogen added, and boron, nitrogen, and sulfur added to the base metal. Milling tests are carried out using TiN, TiCN, and TiAlN coated WC end-mills under various cutting conditions. Boron and nitrogen added steel machined by TiN coated tool shows the most excellent tool wear and surface roughness characteristics. The results might come from BN inclusions in base metal acting as a stress concentration source and lowering strain resistance during cutting process. The relationship between tool wear and surface roughness are also discussed including feed rate effects.

This study understood what effect was produced on the purchasing decision making of outdoor wear by a shopping orientation, fashion involvement and demographic characteristics offered practical suggestions as to what effect was produced on the store selection criteria, product selection criteria for purchasing decision making in purchasing outdoor wear. This research was conducted through a questionnaire survey, and 397 males in were collected for analysis. The results were as follows. First, shopping orientation group was classified into hedonic shopping orientation group and utilitarian shopping orientation group. And it was classified into high fashion involvement group and low fashion involvement group according to fashion involvement. Product selection criteria were classified into 2 factors such as intrinsic attributes and extrinsic attributes. And store selection criteria were classified into 4 factors such as store atmosphere, store environment, promotion and salesmen. Second, there was partly significant difference in product selection criteria, and store selection criteria between utilitarian shopping group and hedonic shopping group. Third, there was significant difference in product selection criteria and store selection criteria between high fashion involvement group and low fashion involvement group. Finally, there was significant difference in the and according to age, job, and income among demographic characteristics.

목적 : 본 연구에서는 임상 작업치료사들이 간헐적 구강식도관을 적절하게 적용할 수 있는 기준에 대한 근 거자료를 제공하고, 간헐적 구강식도관에 대한 인식을 높이고자 하였다. 연구방법 : 간헐적 구강식도관 적용이 의뢰된 자 57명을 대상으로 작업치료사가 간헐적 구강식도관을 적 용하였다. 의무기록 열람을 통해 대상자들의 특징을 조사하였고, 인지 기능 평가를 위해 한국형 간이 정 신상태 검사(Korean version of Mini Mental State Examination; K-MMSE)를 시행하였다. 훈련을 통해 간헐적 구강식도관 적용을 성공한 군과 실패한 군으로 나누어 두 군의 특징을 비교하였다. 결과 : 57명 중 45명(78.9%)은 간헐적 구강식도관을 적용하였으나, 12명(21.1%)은 간헐적 구강식도관 적 용을 실패하여 영양 섭취 방법을 변경하지 않았다. 실패 원인으로는 인지 저하 4명 (33.3%), 적용 방법에 대한 거부 3명(25.0%), 구역 반사 3명(25.0%), 폐렴 2명(16.7%)순으로 조사되었다. K-MMSE 점수에 서 간헐적 구강식도관 적용을 성공한 군의 점수가 실패한 군의 점수보다 유의하게 높았다. 그러나 각 군의 평균 연령, 발병일로부터 연하재활치료 시작일까지의 평균 기간, 발병일로부터 간헐적 구강식도관 훈련일까지의 평균 기간, 연하재활치료 시작일부터 간헐적 구강식도관 훈련일까지의 평균 기간, 간헐적 구강식 도관 훈련 기간에서는 유의한 차이가 없었다. 결론 : 간헐적 구강식도관 적용은 처치 방법과 관리에 대해 충분한 설명을 들은 환자 및 보호자가 동의하였을 경우 실시가능하다. 또한, 인지 기능과 구역 반사가 간헐적 구강식도관을 적용하기에 적합한 환자에게는 과도기적 영양 지원 방법으로 뿐만 아니라 치료적 목적으로 고려될 수 있다고 사료된다. 그러나 폐렴, 역류 등이 의심되는 경우 적용을 제한할 것을 권고하고 장기간 안전하게 적용하기 위해서는 환자 및 보호자의 철저한 관리가 요구된다.

The characteristics of abrasive wear of the rubber matrix composites filled with nano sized silica particles were investigated at ambient temperature by pin-on-disc friction test. The range of volume fraction of silica particles tested are between 11% to 25%. The cumulative wear volume and friction coefficient of these materials on particle volume fraction were determined experimentally. The major failure mechanisms were lapping layers, deformation of matrix, ploughing, deboding of particles and microcracking by scanning electric microscopy photograph of the tested surface. The cumulative wear volume showed a tendency to increase nonlinear with increase of sliding distance. As increasing the silica particles of these composites indicated higher friction coefficient.

Materials design and processing development proposed in this study, aims at contributing to high wear resistant and friction characteristics. To find wear resistant and friction with inner elbow pipe, it is needed hardness and frictional condition test to be capable of supplying with high Cr casting steel. The result of HTV(heat treatment in vacuum) shows that hardness increased with increasing Cr content in % carbide phase. It was about 7∼10% of hardness improvement compared to original casting elbow pipe. This behavior of the hardness of Cr casting steel was explained by the types of chemical bonds that hold atoms together in Cr carbide phase. Through the friction coefficient and wear loss test, with the increasing of Cr wt% reduction in the coefficient of friction and wear loss.

The characteristics of abrasive wear on sliding speed of glass fiber reinforcement (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and surface roughness of these materials on sliding speed were determined experimentally. The major failure mechanisms were lapping layers, deformation of resin, ploughing, delamination, and cracking by scanning electric microscopy (SEM) photograph of the tested surface. As increasing the sliding speed the GF/PUR composites indicated higher friction coefficient. The surface roughness of the GF/PUR composites was increased as the sliding speed was higher in wear test.

The effect of load and sliding speed on abrasive wear characteristics of glass fiber/polyurethane (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. Experimental results showed that the surface roughness of the GF/PUR composites was increased as applied load was higher in wear test. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on applied load and sliding speed for these composites. It could be verified by scanning electric microscopy (SEM) photograph of surface tested that major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking.

The present study was undertaken to evaluate the effect of temperature on the results of Charpy impact test for glass fiber reinforced polyurethane(GF/PUR) composites. The Charpy impact test were conducted in the temperature range from -50˚ to 50˚. The impact fracture toughness of GF/PUR composites was considerably affected by temperature and it was shown that the maximum value was appeared at room temperature. It is believed that sensitivity of notch on impact fracture energy were increased with decrease in temperature of specimen. As the GF/PUR composites exposed in low temperature, impact fracture toughness of composites decreased gradually owing to the decrease of interface bonding strength caused by difference of thermal expansion coefficient between the glass fiber/polyurethane resin. And decrease of interface bonding strength of composites with decrease in specimen temperature was ascertained by SEM photographs of Charpy impact fracture surface.

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

탄소 섬유강화 에폭시기지 복합재의 경면 가공한 스테인리스강 상대재와 마찰과 마모에 바탕을 둔 연구에서는 다음과 같은 결론을 얻었다. (1) 복합재의 비마모율은 하중이 증가하면 N방향와 P방향에서는 증가하는 경향을 보이며,AP방향에서는 감소한다. 이것은 마모 메카니즘의 영향으로 속도가 증가하면 마모 이착막의 생성이 빨라져 이착막 속의 탄소섬유가 윤활제의 역할을 하기 때문이다. (2) 복합재의 마찰계수는 하중이 증가하면 N방향과 AP방향에서는 하중 39.2N까지 증가하다가 그 이상의 하중에서는 감소되며 AP방향에서는 하중이 증가함에 따라 서서히 증가하며, 또한 그 값은 N방향에서 가장 크고, AP방향이 가장 적다. (3) 일방향 탄소섬유 강화 복합재의 마모 거동에 미치는 하중의 효과는 다르며 마찰초반에 발생한 섬유에 의한 쟁기질과 섬유 굽힘 및 미소크랙에 의한 섬유 균열과 파괴에 따른 마모 메카니즘의 형태에 의한 것이다.

탄소 섬유강화 에폭시기지 복합재의 경면 가공한 스테인레스 강 상대재와 마찰과 마모에 바탕을 둔 연구에서 다음과 같은 결론을 얻었다. (1) 일방향 탄소섬유 강화 복합재의 마모 거동에 미치는 미끄럼 방향의 효과는 다르며 작용하는 마모 메커니즘의 형태에 의존한다. (2) 상온에서 경면 가공한 스테인리스 스틸에 대하여 미끄럼이 일어나면 AP 방향에서 높은 마모 저항과 낮은 마찰계수가 관찰되었다. (3) 복합재의 비마모율은 미끄럼 속도가 증가하면 N방향과 P방향에서는 감소하는 경향을 보이며, AP 방향에서는 증가하다가 감소한다. 이것은 마모 메카니즘의 영향으로 속도가 증가하면 마모 이착막의 생성이 빨라져 이착막 속의 탄소섬유가 윤활제의 역할을 하기 때문이다. (4) 복합재의 마찰계수는 미끄럼 속도가 증가하면 3방향 모두 증가하다가 일정한 값에 수렴하면 N방향이 가장 크며, P방향과 AP방향 순이다. 이는 N방향에서 마찰초반에 발생한 섬유의 쟁기질에 의한 상대재 표면의 손상과 돌기변형에 따른 것이며, AP방향의 마찰계수가 가장 낮다.

반응 가스 분압의 조절에 의한 HCD식 이온 도금 법으로 다양한 조성의 Ti(C, N) 경질 피막을 ASP30 공구강에 도금하였고 이 피막의 내마모성에 대한 조성의 영향을 경도, 밀착력 및 마모기구의 변화 등의 관점에서 고찰하였다. 경도는 질소나 탄소와 같은 비금속 성분량의 증가에 비례하지만 탄소함유량의 중가는 밀착력을 오히려 감소시켰다. 이 경향은 피막 밀도가 비교적 작은 정략적비 이하인 구간([C+N]/Ti<1)에서 보다 그 이상인 조성에서 영향이 뚜렷하였다. 따라서 피막의 내마모 특성은 높은 경도를 유지할 수 있는 ([C+N]/Ti>1)인 구역 내에서 밀착력 저하에 의한 adhesive 형태로의 마모 기구 변이를 억제할 수 있는 저 탄소 조성을 가질 때 최대로 된다.

페놀수지 결합재에 PAN섬유(PF), PAN계 탄소섬유(CF) 그리고 아라미드 섬유(AF)를 보강재로 사용하여 단일섬유 보강복합재를 제조하였으며 이들 섬유를 각각 두 종류씩 혼성하여 혼성섬유 보강복합재를 제조하였다. 각 보강복합재를 섬유의 보강분율에 따른 마찰 및 마모특성을 시험하였다. CF 보강복합재(CFRP)가 마찰계수와 마모량이 가장 낮게 나타났으며, PF 보강복합재(PFRP)는 가장 높은 마찰계수와 마모량을 나타내었다. PF에 CF나 AF를 보강한 혼성복합재의 경우 마찰계수가 0.311~0.328로 혼성비에 따라서는 큰 차이를 보이지 않은 반면, PF의 보강분율이 증가할수록 마모량은 증가하였다. CF와 AF를 보강한 혼성복합재의 마찰계수는 0.264~0.309로 가장 낮게 나타났고, AF의 보강분율이 증가함에 따라 마찰계수는 증가하는 양상을 나타내었으며, 가장 적은 마모량과 함께 안정된 마모형태를 보였다.