• 한국조리학회지
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• 제7권1호
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• pp.147-180
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• 2001

Competition of today's markets get to compete the relationship of one system and another system. Competition in relationship of system emphasis molding of cooperate relationship-strycture between enetrprices and It appears competitiveness enriched effects of enterprices in systems. In the rapidly changing economy and marketing situation, Travel agency got worse management situation of themselves more excessive competitiveness then competitiveness efforts between Tourism Relationship Enterprices. So, Relationship marketing will lays a foundation of new travel agency's environment through competitive of relation to travel agency and travel agency, travel agency and hotel or travel agency and airplane. This study's object are present relationships between travel agency and travel relation enterprise of cooperation, complication and competitiveness to relation form. And this study are presents suggestion to generate of hereafter travel relation enterprise through study on relationship with hotel and airplane. A final object of this study are presents a model applys relation method of travel agency and travel agency, hotel and airplane through inspect to specialist analysis. In the result of study, Travel agency are low position and difficult with hotel and airplane at the cooperation but acually It's difficult with travel relation enterprise. So, Travel agency will be operates characteritic system and regulations for win with travel relation enterprise for efficiency of working more than hotel and airplane. Airplane is the best big travel relation enterprise. So, The most airplane has to high cooperate with travel agency. That's why airplane keep going close cooperation with travel agency. Travel agency has to close cooperate with hotels secondly through marketing, exchanging information and union advertisement etc. Hotels are low in complications than travel agency but high in complications than airplane. Although travel relation enterprise are different system individually, because of all of us working with union object, Travel agency and travel compliment-cooperation relationship.relation enterprise has to autonomy behavior with close cooperation through.

• 한국기계가공학회지
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• 제14권3호
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• pp.36-42
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• 2015

The aspherical lens was designed to be able to array a focal point. For this reason, it has very curved surface. The aspherical lens is fabricated by injection molding or diamond turning machine. With the aspherical lens, tool marks and surface roughness affect the optical characteristics, such as transmissivity. However, it is difficult to polish free form surface shapes uniformly with conventional methods. Therefore, in this paper, the ultra-precision polishing method with MR fluid was used to polish an aspherical lens with 4-axis position control systems. A Tool path and polishing mechanism were developed to polish the aspherical lens shape. An MR polishing experiment was performed using a generated tool path with a PMMA aspherical lens after the turning process. As a result, surface roughness was improved from $R_a=40.99nm$, $R_{max}=357.1nm$ to $R_a=4.54nm$, $R_{max}=35.72nm$. Finally, the MR polishing system can be applied to the finishing process of fabrication of the aspherical lens.

• Advanced Composite Materials
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• 제16권4호
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• pp.299-314
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• 2007

In the present study, natural fibers (jute, kenaf and henequen) reinforced thermoplastic (poly(lactic acid) and polypropylene) and thermosetting (unsaturated polyester) matrix composites were well fabricated by a compression molding technique using all chopped natural fibers of about 10 mm long, respectively. Prior to green composite fabrication, natural fiber bundles were surface-treated with tap water by static soaking and dynamic ultrasonication methods, respectively. The interfacial shear strength, flexural properties, and dynamic mechanical properties of each green composite system were investigated by means of single fiber microbonding test, 3-point flexural test, and dynamic mechanical analysis, respectively. The result indicated that the properties of the polymeric resins were significantly improved by incorporating the natural fibers into the resin matrix and also the properties of untreated green composites were further improved by the water treatment done to the natural fibers used. Also, the property improvement of natural fiber-reinforced green composites strongly depended on the treatment method. The interfacial and mechanical results agreed with each other.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.78-84
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• 2012

금형의 공정 과정에서 금형과 성형품 사이에서 발생하는 마찰로 인해 발생하는 금형의 마모가공차로 작용하여 성형 품질을 저하시킬 수 있다. 따라서 금형의 내마모성을 향상시키기 위해 질화나 침탄처리, 화염 및 고주파 표면처리 등의 방법들이 적용되어 왔다. 하지만 형상의 제한이나 제품의 변형 등과 같은 문제점을 수반하고 있기 때문에, 이러한 문제점을 해결할 수 있는 표면처리 방법으로써 레이저 표면처리 기술이 검토되고 있다. 따라서 본 연구에서는 고출력 다이오드 레이저를 이용, 금형재료용 주철의 표면처리를 시도하였다. 앞서 제1보와 제2보의 논문에서는 금형의 재료 및 형상의 차이에 따른 열처리 특성을 비교하였다면, 본 논문에서는 열처리 후 생성되는 경화부, 경계부위 및 모재의 조직적 차이를 분석하기 위해 광학 현미경 및 전자 현미경을 이용하여 미세조직을 관찰하고, EDS를 통해 조직의 상태를 파악하였다. 미세조직 관찰 결과, 경화부는 침상의 마르텐사이트 조직이 형성되어 있었다.

• 산업경영시스템학회지
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• 제39권1호
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• pp.130-139
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• 2016

The purpose of this paper is to analyze the problems and the sources of defective products and draw improvement plans in a small plastic boat manufacturing process using TOC (Theory Of Constraints) and statistical analysis. TOC is a methodology to present a scheme for optimization of production process by finding the CCR (Capacity Constraints Resource) in the organization or the all production process through the concentration improvement activity. In this paper, we found and reformed constraints and bottlenecks in plastic boat manufacturing process in the target company for less defect ratio and production cost by applying DBR (Drum, Buffer, Rope) scheduling. And we set the threshold values for the critical process variables using statistical analysis. The result can be summarized as follows. First, CCRs in inventory control, material mix, and oven setting were found and solutions were suggested by applying DBR method. Second, the logical thinking process was utilized to find core conflict factors and draw solutions. Third, to specify the solution plan, experiment data were statistically analyzed. Data were collected from the daily journal addressing the details of 96 products such as temperature, humidity, duration and temperature of heating process, rotation speed, duration time of cooling, and the temperature of removal process. Basic statistics and logistic regression analysis were conducted with the defection as the dependent variable. Finally, critical values for major processes were proposed based on the analysis. This paper has a practical importance in contribution to the quality level of the target company through theoretical approach, TOC, and statistical analysis. However, limited number of data might depreciate the significance of the analysis and therefore it will be interesting further research direction to specify the significant manufacturing conditions across different products and processes.

• 소성∙가공
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• 제14권3호
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• pp.282-290
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• 2005

Nowadays, TFT-LCD is widely used as display unit of many digital devices. And, the backlight unit(BLU) is used as a light source of TFT-LCD module. In the backlight unit, the most important component is a light guide, which guides the input light to the TFT-LCD module uniformly. Recently, many researchers have focused on improving the efficiency of BLU by changing the design and structure of a light guide. In the present paper, a series of simulation was performed to find the optimal luminance distribution of emanated light from the given geometry as the first step. From the results of simulations for the light guide with given V-groove pattern, the emanated light from it is mostly affected by the groove angle. In the case of acute angle, about 74 degrees was found as optimal angle to satisfy the restrictions of angular luminance distribution, FWHM, the maximum luminance, etc. However, as far as the average luminance value was concerned, the case of 120 degrees(abtuse angle) was found to be the best while prism films were added to the BLU. As a next step the light guide samples of 74 and 120 degrees were manufactured by DSF method, which was recently proposed by the authors. Of course, most of design parameters were chosen by the aid of simulation results. Finally, the results of average luminance values were compared between the simulation and DSF molded samples.

• 한국수소및신에너지학회논문집
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• 제23권2호
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• pp.134-142
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• 2012

A bipolar plate is a major component of a fuel cell stack, which occupies 50~60% of the total weight and over 50% of the total cost of a typical fuel cell stack. In this study, a composite bipolar plate is designed and fabricated to develop a compact and light-weight direct methanol fuel cell (DMFC) stack for a small-scale Unmanned Aerial Vehicle (UAV) application. The composite bipolar plates for DMFCs are prepared by a compression molding method using resole type phenol resin as a binder and natural graphite and carbon black as a conductor filler and tested in terms of electrical conductivity, mechanical strength and hydrogen permeability. The flexural strength of 63 MPa and the in-plane electrical conductivities of 191 S $cm^{-1}$ are achieved under the optimum bipolar plate composition of phenol : 18%; natural graphite : 82%; carbon black : 3%, indicating that the composite bipolar plates exhibit sufficient mechanical strength, electrical conductivity and hydrogen permeability to be applied in a DMFC stack. A DMFC with the composite bipolar plate is tested and shows a similar cell performance with a conventional DMFC with graphite-based bipolar plate.

• Composites Research
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• 제23권3호
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• pp.58-63
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• 2010

MWCNT의 형상비 차이에 따른 MWCNT/에폭시 복합재료의 인장 및 굽힘 특성과 전기전도도를 비교하였다. 호모믹서(homomixer)와 3단롤밀(three-roll mill)을 사용하여 분산된 MWCNT와 에폭시 혼합물을 금형에 부어 압축 성형법으로 시편을 제조하였다. 에폭시 내 MWCNT의 분산 정도를 평가하기 위해 SEM을 사용하여 시편의 파단면을 관찰하였다. MWCNT의 첨가로 인해 인장강도는 최대 7%증가 하였으나 굽힘강도는 증가가 미미하였으며 형상비가 가장 큰 MWCNT의 경우에는 감소하였다. MWCNT 포함량을 변화시켰을 때 CM-95의 경우 인장강도는 1wt%에서, 굽힘강도는 0.5wt%에서 최대값을 보였으나 더 많은 포함량에서는 감소하였다. MWCNT/에폭시 복합재료의 두께 방향 및 면내방향 전기전도도는 2단자법에 의한 저항값으로부터 계산되었으며 MWCNT의 형상비가 클수록, 또 포함량이 증가할수록 전기전도도 값은 증가하였다.

• 폴리머
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• 제24권6호
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• pp.845-853
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• 2000

DSC와 TGA 분석으로 탄소섬유/페놀수지 복합재의 최적 경화조건과, 탄화조건을 선정하고 핫프레스 몰딩 방법으로 복합재를 제조한 후 140$0^{\circ}C$까지 탄화하였다 또한 층간전단강도의 개선에 효과적이라 생각되는 흑연분말, 카본블랙, 분쇄된 탄소섬유 및 탄소섬유 매트를 첨가하여 이러한 첨가제가 밀도 및 기공도에 미치는 영향과 ILSS, 굽힘강도와 같은 기계적 물성과의 상관관계에 대하여 연구하였다. 흑연분말을 약 9 vol% 첨가한 경우 가장 큰 ILSS 값과 굽힘강도 값을 나타내었고 카본블랙의 경우, 약 3 vol%에서 ILSS 값이 약간 증가하였으나 굽힘강도는 감소하였다. 분쇄된 탄소섬유와 탄소섬유 매트 첨가시 수지부족과 열수축에 의한 층간분리가 발생하여 밀도와 ILSS 및 굽힘강도를 감소시키는 결과를 나타내었다.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.1-6
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• 2018

하이드로포밍 기술은 지난 20년간 자동차부품의 적용을 중심으로 비약적인 발전을 해 왔다. 이 기술은 자동차 산업응용분야에 많은 장점을 가지고 있는데 이는 더 나은 구조적 강건성, 부품수 감소에 기인한 비용절감, 재료절약, 무게감소, 낮은 스프링백현상, 개선된 강도, 내구성 향상, 설계 유연성 등이다. 하이드로포밍 부품의 성형성 검토를 위하여 다양한 컴퓨터 시뮬레이션 기술 등이 발달해 왔으며 이를 통해 성형 가능성을 검토하는 것과 동시에 성형을 위하여 벤딩 공정, 프리포밍공정, 다이클로징 공정 등의 효율적인 공정을 수립하여 하이드로포밍 부품들을 설계하고 있다. 이에 본 연구에서는 하이드로포밍 부품 설계 시 고려사항 중 성형량, 부품의 단면길이(하이드로포밍 프레스 용량에 맞는), 최소 곡률(하이드로포밍 압력에 따른 곡률 영향 평가) 등을 제시하고 실제 자동차용 리어 서브-프레임 부품의 단면분석을 실시함으로써 하이드로포밍 성형을 위한 설계 방안을 제시하고자 한다. 아울러 하이드로포밍 공정인자 중 프리벤딩, 축피딩, 유압 압력, 프레스 하중, 마찰 등의 효과를 분석하여 이들 공정이 직접적인 하이드로포밍 성형에 필요인자 인지 등을 고찰하였다.