• Composites Research
• /
• 제15권4호
• /
• pp.17-22
• /
• 2002

미세 직경을 갖는 복합재료 나선형 스프링 (CS)가 광점퍼코드 (OJC)를 보강하기위한 매체로써 개발되었다. 이 스프링의 외경은 약 2~3mm로써 광점퍼코드에 갑작스런 측면 하중으로 부터 광섬유의 손실을 막기위해 삽입 보강할 수 있도록 제작되었다. 섬유 형태 (Y-type)와 밴드 형태 (B-type)의 복합재료 스프링이 제작되어 그 효과를 비교하였다. 측면 하중에 대한 기계적 특성은 동일 직경의 금속 스프링 및 일반 광점퍼코드의 물성치와 비교하여 제시하였다. 실험 결과로부터 복합재료 스프링이 보강된 광점퍼코드의 경우 굽힘에 대한 높은 저항력을 지니고 있음에 따라 광섬유의 내부 손상에 의한 광 손실의 감소률이 낮음을 알 수 있었다 얻어진 주요 결과들은: (1) Y-type의 CS의 경우 B-type과 비교하여 높은 측압 저항력을 지님을 알 수 있었다 (2) 일반 OJC와 비교하여 CS-OJC의 경우 광 손실이 현격이 낮음을 알 수 있었다. (3) 일반 스프링의 측압 하중시의 응력 분포 형태를 제시하였으며. 실험으로부터 얻어진 결과로부터 복합재료 스프링이 보강된 광점퍼 코드의 경우 매우 높은 구조적 안정성을 보임을 알 수 있었다.

• Journal of Electrical Engineering and Technology
• /
• 제1권2호
• /
• pp.211-215
• /
• 2006

This paper presents a new structure for the universal motor using soft magnetic composite (SMC). The stator for this new type of motor is made by combination of the SMC pole and the silicon steel yoke. The shape of the 3D SMC pole is designed to minimize ohmic loss and amount of stator coil. To design the pole shape, the 3D analysis in the design procedure is replaced with an equivalent 2D analysis. Finally, the optimal shape is analyzed by 3D FEM and the performance is discussed.

• Restorative Dentistry and Endodontics
• /
• 제15권2호
• /
• pp.17-33
• /
• 1990

The purpose of this study was to evaluate the fracture toughness of dental composite resins and to investigate the filler factor affecting the fracture behaviour on which the degree of fracture toughness depends. Six kinds of commercially available composite resin;, including two of each macrofilled, microfilled, and hybrid type were used for this study, The plane strain fracture toughness ($K_{10}$) was determined by three-point bending test using the single edge notch specimen according to the ASTM-E399. The specimens were fabricated with visible light curing or self curing of each composite resin previously inserted into a metal mold, and three-point bending test was conducted with cross-head speed of 0.1mm/min following a day's storage of the specimens in $37^{\circ}C$ distilled water. The filler volume fractions were determined by the standard ashing test according to the ISO-4049. Acoustic Emission(AE), a nondestructive testing method detecting the elastic wave released from the localized sources In material under a certain stress, was detected during three-point bending test and its analyzed data was compared with, canning electron fractographs of each specimen. The results were as follows : 1. The filler content of composite resin material was found to be highest in the hybrid type followed by the macrofilled type, and the microfilled type. 2. It was found that the value of plane strain fracture toughness of composite resin material was in the range from 0.69 MPa$\sqrt{m}$ to 1 46 MPa$\sqrt{m}$ and highest In the macrofilled type followed by the hybrid type, and the microfilled type. 3. The consequence of Acoustic Emission analysis revealed that the plane strain fracture toughness increased according as the count of Acoustic Emission events increased. 4. The higher the plane strain fracture toughness became, the higher degree of surface roughness and irregularity the fractographs demonstrated.

• Restorative Dentistry and Endodontics
• /
• 제19권1호
• /
• pp.194-204
• /
• 1994

The purpose of this study was to evaluate the surface hardness of composite resins according to heat treatment. storage condition and storage time. In this study. two kinds of composite resin inlays and one kind of conventional posterior composite resin were used as experimental materials. One hundred eighty composite resin specimens were constructed from composite resin inlays and conventional posterior composite resin. The conditions of this study were heat treatment. storage condition and storage time. Hardness readings were taken from the top surface of each samples using the Vickers microhardness tester(MHT-l. Matsuzawa. Japan}. The following results from this study were obtained: 1. Regardless of storage condition. both composite resin inlay and conventional posterior composite resin have a higher surface hardness under heat treatment than not. 2. Composite resins with heat treatment have a higher surface hardness under dry storage than under water immersion. 3. In case of Clearfil Photo Posterior and Brilliant Enamel with heat treatment. there was no significant difference with time. but Clearfil CR Inlay with heat treatment. there was statistical difference after 24 hours. 4. Surface hardness of composite resins with coarse hybrid type was higher than that of composite resin with fine hybrid type.

• Food Science and Biotechnology
• /
• 제15권1호
• /
• pp.133-137
• /
• 2006

Wheat gluten-chitosan composite film (WGCCF) can prevent moisture migration and enhance the antimicrobial properties of gluten in intermediate-moisture foods like sandwiches. To mimic the structure of actual sandwich-type products we developed multi-layer food models, where moisture content and water activity differ. Water activity gradients direct moisture migration and therefore determine product characteristics and product stability. A 10% wheat gluten film-forming solution was mixed with chitosan film-forming solution (0-3%, w/w) and evaporated to generate WGCCF. Addition of 3% chitosan enhanced the mechanical properties of the film composite, lowered its water vapor permeability, and improved its ability to protect against both, Streptococcus faecalis and Escherichia coli, in a 24 hr sandwich test (reduction of 1.3 and 2.7 log cycles, respectively, compared to controls). Best barrier and antimicrobial performance was found for 3% chitosan WGCCF at pH 5.1. Film of this type may find application as barrier film for intermediate-moisture foods.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
• /
• pp.935-937
• /
• 1999

In this study, 1-3 type composite specimens were fabricated with PZT powders prepared by the molten-salt synthesis method and Eccogel polymer matrix. A virtual level-meter was fabricated with a 1-3 type composite probe and electronic unit for underwater application. There was no difference in values between a virtual and measured level on its level meter.

• 한국결정성장학회지
• /
• 제21권6호
• /
• pp.253-258
• /
• 2011

본 연구에서는 1_3형 압전복합체(1-3 type piezo-composite)의 전기-기계적 성능을 수치적으로 분석하였다. PZT 세라믹스의 압전물성 계산치를 실험치와 비교하여 수치 해석방법의 정확성을 검증하였다. 그리고 구성재료의 부피 비 및 물성, PZT 기둥의 종 횡비(aspect ratio) 등이 복합체의 $k_t$특성에 미치는 영향을 해석하였다. 그 결과, PZT 부피 비가 30 vol%까지 증가함에 복합체의 $k_t$ 특성은 급격하게 증가하다가 그 이상의 영역에서는 일정한 값에 수렴한다. 그리고 상대적으로 유연한 폴리머를 사용한 복합체가 전반적으로 우수한 $k_t$ 특성을 갖는다. 또한 PZT 부피비가 30 % 이하인 경우, 복합체의 $k_t$ 특성은 PZT 기둥의 종횡 비에 많은 영향을 받는다. 그러므로 $k_t$ 특성 향상을 위해서는 상대적으로 유연한 폴리머 및 우수한 압전특성의 PZT를 사용하여 복합체를 구성하는 것이 유리하다.

• 한국전기화학회:학술대회논문집
• /
• 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
• /
• pp.201-206
• /
• 2005

본 연구는 기 개발 완료된 천연가스차량용 200bar급 Type 3 복합재 압력용기를 개발로 축척된 핵심요소기술과 실질적인 경험을 바탕으로 수소연료전지 차량에 탑재할 350bar급 Type 3 복합재 압력용기에 대한 설계/해석과 시험평가의 핵심적인 사항을 고찰하였다. 설계/해석에는 350bar급 Type 3 복합재 압력용기에 대한 3차원 비선형 유한요소 모델링 및 해석기법이 제시되었고, 설계된 라이너형상과 와인딩 패턴을 이용하여 필라멘트 와인딩 공법으로 1차시제품을 제작하였다. 제작된 시제품에 대하여 파열시험 및 반복피로시험을 수행하여 설계/해석 기법의 타당성을 검증하였다.

• 한국분말재료학회지
• /
• 제23권1호
• /
• pp.33-37
• /
• 2016

10 wt.% and 20 wt.%$Li-TiO_2$ composite powders are synthesized by a sol-gel method using titanium isopropoxide and $Li_2CO_3$ as precursors. The as-received amorphous 10 wt.%$Li-TiO_2$ composite powders crystallize into the anatase-type crystal structure upon calcination at $450^{\circ}C$, which then changes to the rutile phase at $750^{\circ}C$. The asreceived 20 wt%$Li-TiO_2$ composite powders, on the other hand, crystallize into the anatase-type structure. As the calcination temperature increases, the anatase $TiO_2$ phase gets transformed to the $LiTiO_2$ phase. The peaks for the samples obtained after calcination at $900^{\circ}C$ mainly exhibit the $LiTiO_2$ and $Li_2TiO_3$ phases. For a comparison of the photocatalytic activity, 10 wt.% and 20 wt.% $Li-TiO_2$ composite powders calcined at $450^{\circ}C$, $600^{\circ}C$, and $750^{\circ}C$ are used. The 20 wt.%$Li-TiO_2$ composite powders calcined at $600^{\circ}C$ show excellent efficiency for the removal of methylorange.

• 복식문화연구
• /
• 제23권3호
• /
• pp.512-522
• /
• 2015

The aim of this study was to investigate the change in women's somatotype with aging. The subjects were 1,123 women aged 40~69. Their anthropometric data were from the 6th Size Korea. The data were analyzed by factor analysis and cluster analysis. Seven factors were extracted: body mass, body length, back shoulder, arm length factor, front interscye factor, body rise factor, and shoulder angle. The upper body types of middle-aged and elderly women were classified into five types: skinny, short stout body type with forward posture, composite, tall & full body type, and short & skinny. The skinny and composite body type appeared more often than the short stout body type in the early 40s of Korean women. Starting in the mid-50s, composite body type was less often found. However, the number of women with short stout body type increased. In the 60s, the number of women with short stout and tall & full body types decreased. These results reveal that the body types of middle-aged and elderly women changed with some pattern with aging. And women in their early 40s, mid-50s, and 60s women had different body shapes and postures.