• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1487-1492
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• 2010

The objective of this study is to design the conformal cooling channels for the mould of a plastic drawer of a refrigerator by analysis of three-dimensional injection molding. In order to obtain the desired design of the conformal cooling channels, the influence of the diameter and the position of the conformal cooling channels on the moulding characteristics and the product qualities were quantitatively examined. From the results of the examination, an optimal design of the conformal cooling channels, which ensures uniform cooling and minimum potential deformation of the molded drawers, was estimated. By comparing the designed mould and a conventional mould with linear cooling channels from the viewpoints of the product qualities as well as cooling and cycle times, it was shown that the mould with conformal cooling channels can simultaneously improve the productivity of the injection moulding process and the product qualities.

• Composites Research
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• v.34 no.5
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• pp.269-276
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• 2021

PCM (Prepreg Compression Molding) process is a high-speed molding technology that can manufacture high-quality CFRP (Carbon Fiber Reinforced Plastic) parts. Compared to the autoclave process, it generates less waste and can significantly reduce cycle time, so various studies are being conducted in the aerospace and automobile industries. In this study, in order to improve the quality of the PCM process, a molding method was developed to increase the compression pressure of the press step by step according to the curing behavior of the prepreg. It was confirmed that this multi-stage compression molding technology is a good means to produce high-quality CFRP products and shorten cycle times. And, the laminated prepreg at room temperature was immediately put into the mold and preheated and molded at the same time, so that it could be molded without a separate preheating process. In addition, as a result of applying the same process conditions optimized for flat plate molding to three-dimensional shapes, a product similar to a flat plate in appearance could be made without the process of establishing process conditions.

• Korean Journal of Psychosomatic Medicine
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• v.7 no.1
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• pp.3-9
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• 1999

Abnormal external appearance may cause psychiatric trauma or problem in social adaption. The plastic surgeons should consider the patient's quality of life, and their roles are correcting psychiatric and emotional trauma as well as external appearance which help the patient adapting social life. Because the patients in plastic surgery have higher level of expectation for the result of their operation, it is necessary for the surgeons to explain precisely the procedure and possible complications precisely at preoperative meeting and to maintain the good doctor-patient relationship at postoperative follow-up period. In case if the patient dissatisfy the postoperative result, it is recommended to listen the second opinion from another plastic surgeon. If the patient still dissatisfy, then the patient should be consulted to psychiatrist.

• The Korean Journal of Rheology
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• v.8 no.2
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• pp.78-91
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• 1996

단섬유 보강 플라스틱 복합재료에 사출성형에서 섬유배향은 금형 충전 공정 중의 유동장에 의해 결정되고 섬유의 배향 상태는 역으로 유동장에 영향을 미친다. 단섬유에 의 한 추가적인 응력을 포함하는 Dinh과 Armstrong의 이방성 구성방정식을 충전유동과 섬유 배향의 연계해석에 도입하였다. 충전유동의 해석은 새로운 압력 지배방정식과 에너지 방정 식을 유한요소법과 유한차분법을 이용하여 풀고 동시에 2차 배향 텐서의 변화방정식을 4차 Runge-kutta 방법으로 풀었다. 섬유의 배향상태를 구한 후에 일방향성 복합재료의 Halpin-Tsai 식과 배향 평균모델을 도입하여 사풀성형품의 이방성 기계적 성질이 예측되었 다. 직사각형 캐비티에서 수치해석결과를 실험결과와 비교하였다. 섬유배향과 유동과의 상호 연계작용을 특히 게이트 근처에서 섬유배향에 영향을 미치며 수치해석 결과는 벽면 근처에 서 유동방향으로 배향하는 shell층을 과대 예측함을 알수 있었는데 이는 배향 텐서 변화 방 정식의 최종근사에서 기인하는 오차로 판단된다. 수정된 복합최종 근사를 바탕으로 예측된 이방성 기계적 성질이 기존의 복합최종 근사에 기초한 예측보다 실험 결과에 정량적으로 보 다 잘 일치하였다.

• The Korean Journal of Rheology
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• v.5 no.2
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• pp.109-124
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• 1993

본 연구의 목표는 임의의 3차원 사출성형 금형 공간내에서 단섬유 강화 플라스틱의 충전 공정에서의 과도기적 섬유방향성을 예측하는 수치해석 프로그램의 개발에 있다. Hele-Shaw 방정식에 단섬유에 의해서 추가된 응력을 고려한 Dinh-Armstrong의 모델을 도 입함으로써 새로운 충전과정의 압력 지배 방정식이 유도되었다. 새로운 압력지배 방정식은 단섬유에 의한 응력 때문에 몇 개의 새로운 항들을 포함하고 있다. 충전 과정의 해석은 새 로운 압력지배방정식과 에너지 방정식을 유한효소법과 유한 차분법을 이용하여 풀고 동시에 배향텐서(roientation tensor)의 변화 방정식을 4차 Runge-Kutta 방법을 이용하여 풀었다. 단섬유 배향 텐서를 텐서의 변환 법칙을 이용하여 임의의 3차원 금형 공간내의 모든유한요 소의 중심에서 두께방향의 모든유한 차분 격자를 따라 계산하였다. 이러한 방법으로 임의의 3차원 사출성형 금형 공간내에서 비등온 충전유동과 과도기적 3차원 섬유배향상태를 서로의 상호작용을 고려하여 수치 모사하여 다양한 유동 형태에 따른 단섬유 배향 상태의 변화에 대하여 알아보고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.483-490
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• 2013

In aluminum sheet metal forming, the conventional forming methods of T4 or T6 heat-treated sheets result in low formability and dimensional accuracy. This study suggests a new forming method for aluminum sheets called as hot forming quenching (HFQ) that solves the problems faced in the conventional method. HFQ combines the heat treatment and forming processes through the forming die during the quenching of a solid solution. To evaluate the application of HFQ to the sheet forming of aluminum, an Erichsen and V-bending test are performed in this study to measure the dimensional accuracy and formability, which are then compared with those of the conventional forming method. Furthermore, the strength and hardness of the products formed by HFQ are measured to confirm the degradation in mechanical properties compared with the conventional forming method, which shows the validity of the application of HFQ to aluminum sheet metal forming.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.35-41
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• 2013

In injection molding, the mold temperature is one of most important process parameters that affect the flow characteristics and part deformation. The mold temperature usually varies periodically owing to the effects of the hot polymer melt and the cold coolant as the molding cycle repeats. In this study, a pulsed mold temperature control was proposed to improve the part quality as well as the productivity by alternatively circulating hot water and cold water before and after the molding stage, respectively. Transient thermal-fluid coupled analyses were performed to investigate the heat transfer characteristics of the proposed pulsed mold heating and cooling system. The simulation results were then compared with those of the conventional mold cooling system in terms of the heating and cooling efficiencies of the proposed pulsed mold temperature control system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1933-1947
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• 1991

The synthesis of supplementary features of injection molded parts has been done empirically, since it requires profound knowledge about the features' moldability and causal effects on the properties of the part, which are not available to designers through current CAD systems. RIBBER is a knowledge module which contains knowledge to permit non-experts as well as mold design experts to generate acceptable supplementary features of injection molded parts. A knowledge-based CAD system is constructed by adding the knowledge module, RIBBER, for mold feature synthesis and appropriate CAE programs for mold design analysis to an existing geometric modeler in order to provide designers, at the initial design stage, with comprehensive process knowledge-based CAD system is a new tool which enables the concurrent design and CIM with integrated and balanced design decisions at the initial design stage of injection molding.

• Journal of Chest Surgery
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• v.30 no.4
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• pp.396-401
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• 1997

Tailoring thoracoplasty is employed prior to, following, or concomitant with pulmonary resection when it is anticipated that insufHclent lung tissue will remain to fill the pleural space following a pulmonary resection. This study reviewed a series of eight patients treated with tailoring thoracoplasty between 1990 and 1995. Indications were to close a persistent space In four patients and to tailor the thoracic cavity to accept diminished lung volume concomitant with a pulmonary resection in the other four patients. The primary underlying disease was lung cancer in three patients and pulmonary tuberculosis In five patients, two of whom had concomitant aspcrgilloma, two, pneumothora , and one, empyema with bronchopleural fistula. In four patients with a prior pulmonary resection, the tailoring thoracoplasty was performed within eight days after the resection surgery. There was no failure to accommodate the thoracic cavity to insufficient lung tissue, even though two patients needed a second thoracoplasty. We conclude that tailoring thoracoplasty may be performed to close anticipated persistent pleural space and to accommodate diminished lung volume with acceptable cosmetic results Early, after, or concomitant with pulmonary resection in selected patients.

• Journal of the KSME
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• v.33 no.2
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• pp.134-144
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• 1993

조립성 평가법은 동시공학을 추진하는 하나의 도구로써 전자산업의 시장과 환경의 변화에 대응할 수 있는 토탈 개발 시스템이다. 조립성 평가법으로부터 얻는 효과는 개발 납기의 단축, 제조원 가의 절감, 생산성 향상, 품질 향상 등을 꼽을 수 있다. 조립성 평가법의 적용 추진을 지속하여 제품 설계자들의 설계 기술이 질적으로 향상되어 고객이 원하는 경쟁력 있는 제품을 제공할 수가 있도록 해야할 것이고, 따라서 향후 모든 상품화 설계는 조립성 평가법이 완제품 제조업의 신 상품 개발 기본 업무로 규정되어야 할 것이다. 제조성이 고려된 제품의 구조와 부품의 형상으 로부터 공정설계, 제조원가 산출 및 양산시에 필요한 전용기 등을 도출하여 개발해야 할 설비를 동시에 개발 착수할 수 있고, 소재개발로부터 신규 부품과 그 제작 공법의 개발까지 모든 분야에 대하여 제안해 줄수 있는 제조성 평가법이 개발되어야 하고, 앞으로는 PCB조립성 평가법, 소재 가공성(성형성, 절삭성, 접합성, 처리성)평가법, 재활용 평가법, 신뢰성 평가법 등이 포함된 지능형 설계 평가법의 출현을 기대해야 할 것이다.