• 소성∙가공
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• 제32권1호
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• pp.5-11
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• 2023

The aim of this study is to manufacture an aluminum pipe yoke of automotive steering system for lightweight. In a multistage cold forging process for aluminum pipe yoke, the surface defects frequently occur due to excessive deformation or friction during extrusion process for forming hollow pipe part. It is import to reduce the friction between the material and the forging die. This study investigated a multistage forging process with sliding die to reduce friction for aluminum pipe yoke. After evaluating by FE analysis, the forging experiment with the sliding die was carried out. As a result, it was possible to manufacture a sound aluminum pipe yoke.

• 한국식품과학회지
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• 제38권3호
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• pp.408-413
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• 2006

본 연구에서는 국내산 포도주의 감산 연구를 위해 Campbell Early를 이용하여 control, precipitation, cold stabilization, MLF, carbonic maceration, cold fermentation과 같이 6가지 다른 방법으로 산도 감소 효과를 실험해 보았다. 6가지 방법으로 제조한 포도주가 $4-5^{\circ}Brix$의 당도와 6.8-7.7%의 알코올 함량을 나타냄으로써 산도 감소를 위해 발효 방법을 달리해도 정상적인 발효가 진행되었음을 확인할 수 있었다. 그리고 숙성 중에 pH와 총산, 유기산 함량을 측정하여 감산의 정도를 알아본 결과 cold stabilization을 제외하고는 각 포도주들이 control보다 pH는 증가하고 총산은 감소하였다. 특히 carbonic maceration은 총산이 0.42 g/100 mL로 산도 감소에 효과적인 방법임을 확인할 수 있었다. 이는 HPLC를 이용하여 측정한 유기산 함량에서도 알 수 있었다. Control의 tartaric acid가 2,928 ppm인 반면 precipitation은 2,346 ppm으로 precipitation으로 인해 tartaric acid가 감소했음을 확인할 수 있었다. Control의 malic acid는 2,421 ppm, lactic acid는 486 ppm이었으나 MLF의 경우는 malic acid가 828 ppm으로 감소했고, lactic acid는 2,394 ppm으로 증가한 것을 확인할 수 있었다. 그리고 carbonic maceration은 malic acid가 993 ppm으로 눈에 띄게 감소하였고, cold fermentation은 유기산 함량이 전체적으로 감소한 것을 확인할 수 있었다. 산도가 감소한 포도주의 품질을 평가하기 위해 총페놀 함량, hue, 색도, 관능검사를 실시한 결과 산도 감소 효과가 우수한 precipitation과 carbonic maceration 방법으로 제조한 포도주가 품질 평가에서도 우수하게 나타났다. 이로써 본 연구에서는 carbonic maceration과 precipitation이 Campbell Early 포도주에 적합한 감산 방법이며, 제조한 포도주도 선명하고 진한 붉은색을 가지며, 포도향이 풍부하고, 신맛이 강하지 않음을 확인할 수 있었다.

• 수산경영론집
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• 제30권1호
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• pp.119-147
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• 1999

This article is subject to the rationalization of the cold-storage warehouse management, which gives the stabilization of the fishery production and the food life with respect to fisheries industry. In this point of view, the article examines to the structure of the cold-storage warehouse industry from the perspective of the industrial organization. To put it concretely, the article intends to apprehend the state of the structure of the industry and analyze the cold-storage warehouse's management activities. In addition, I try to find know the factors that affect the management performance(profitablity) of the industry through the cross-sectional correlation analysis. Finally, the conclusion of the article can be described as follows : \circled1 On the basis of the cold-storage capacity, there is the tendency that the industry concentrate in the area of Pusan(41.7%). \circled2 By formulating step of development of the industry, it is divided by six types. Type I is designed as raw material-storage warehouse for self-processing. Type IIis the raw material-storage warehouse for self-processing and storage-sale warehouse. Type III is the raw material-storage warehouse for self.distribution. Type IV is the raw material-storage warehouse for self-distribution and storage-sale warehouse. Type V is the net storage-sale warehouse. Type Ⅵ is the physical distribution center warehouse. Although each region has one representative type,6 types exist in all regions. \circled3 The competition structure of the industry has double structure on the basis of cold-storage capacity. \circled4 With respect to the management activity of the cold-storage warehouse, there is no change or even a decrease not increasing or not any change in sales from 1996 to 1997 \circled5 In order to try to induce the amount of shipper's materials, services that a cold-storage warehouse supply with its users include a custody-fee discount, a distribution-process service, a finance service, quality management service and so on. One of the best attractive services is the custody-fee service. \circled6 In the structure and management activity of the industry, the factors that affect management performance (profitablity) are a custody-fee discount, sales ability and capital structure of individual firm. Positive factor is sales ability and capital structure of individual firm. But, The custody-fee discount turns out to be a negative capital structure of individual film.

• 소성∙가공
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• 제6권5호
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• pp.395-399
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• 1997

There exists a certain functional relation between Vickers hardness and flow stress in the strain-hardened material. Using this relation, the Vickers hardness values in the strain-hardened material can be converted into the flow stress values in good approximation. Therefore, the information about the flow stress distribution in the material can be easily acquired through a forming experiment. That makes it possible to simulate the process state for a critical moment of cold forging under the given boundary conditions very quickly without calculating the foregoing history of the actual deformation from the beginning.

• 소성∙가공
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• 제6권3호
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• pp.227-232
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• 1997

This study is concerned with the rotary powder compacting by the cold rotary forging process. An experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The detailed comparisons of several mechanical test by rotary powder forging and rotary powder compacting process are given. It is found that the highly densified P/M parts can be obtained and this process is very effective for improving quality of the powder products.

• 소성∙가공
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• 제9권2호
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• pp.159-164
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• 2000

In this paper, a computer simulation technique for the forging process having a floating die is presented. The penalty rigid-plastic finite element method is employed together with an iteratively force-balancing method, in which the convergence is achieved when the floating die part is in force equilibrium within the user-specified tolerance. The force balance is controled by adjusting the velocity of the floating die in an automatic manner. An application example of a three-stage cold forging process is given.

• 한국축산식품학회지
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• 제33권6호
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• pp.723-729
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• 2013

In this study, the quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen beef were examined. The loin and round of second grade Hanwoo were sliced into 5-7 cm thickness and packed with aerobic packaging. The packaged beef samples, which were frozen by air blast freezing at $-45^{\circ}C$ and electro-magnetic freezing at $-55^{\circ}C$, were thawed by 4 thawing methods with refrigeration ($4{\pm}1^{\circ}C$), room temperature (RT, $25^{\circ}C$), cold water ($15^{\circ}C$), and microwave (2450 MHz). These samples were thawed to the point, which were core temperature reached $0^{\circ}C$. Analyses were carried out to determine drip and cooking loss, water holding capacity (WHC), moisture contents and sensory evaluation. Frozen beef thawed by microwave indicated a lower drip loss (0.66-2.01%) than the other thawing methods (0.80-2.50%). Cooking loss after electro-magnetic freezing indicated 52.0% by microwave thawing for round compared with 41.8% by refrigeration, 50.1% by RT, and 50.8% by cold water. WHC thawing by microwave with electro-magnetic freezing didn't showed any difference depending on the thawing methods, while moisture contents was higher thawing by microwave with electro-magnetic freezing than refrigeration (71.9%), RT (75.0%), and cold water (74.9%) for round. The texture of sensory evaluation for round thawed by microwave result was the highest than refrigeration (4.7 point), RT (6.4 point) and cold water (6.6 point), while sensory evaluation was no significant difference. Therefore, it was shown that microwave thawing is an appropriate way to reduce the deterioration of meat quality due to freezing.

• 소성∙가공
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• 제28권6호
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• pp.321-327
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• 2019

In this study, a hot and cold forging process was investigated to produce a complex-shaped hub of dual clutch transmission with low material loss and high productivity. The process was designed by the commercial finite element (FE) analysis program, DEFORM-2D (hot forging) and 3D (cold forging). And, the material flow and ductile fracture characteristics were studied to check the surface crack initiation of the specimen. The simulation results indicated that the proposed process could manufacture the complex-shaped hub with no surface crack and high-efficiency compared to the conventional machining process. For verification the numerical results, the hub of the SCM440 was fabricated by the proposed process and the mechanical properties and microstructure evolution were studied. It was demonstrated that the suggested hot and cold forging process might be useful in producing the key components of the automobile industry as a high-efficiency and environmentally friendly process.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.867-880
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• 2015

Mechanical fastening is still one of the main methods used for joining components. Different techniques have been applied to reduce the effect of stress concentration of notches like fastener holes. In this work we evaluate the feasibility of combining laser shock peening (LSP) and cold expansion to improve fatigue crack initiation and propagation of open hole specimens made of 6061-T6 aluminum alloy. LSP is a new and competitive technique for strengthening metals, and like cold expansion, induces a compressive residual stress field that improves fatigue, wear and corrosion resistance. For LSP treatment, a Q-switched Nd:YAG laser with infrared radiation was used. Residual stress distribution as a function of depth was determined by the contour method. Compact tension specimens with a hole at the notch tip were subjected to LSP process and cold expansion and then tested under cyclic loading with R=0.1 generating fatigue cracks on the hole surface. Fatigue crack initiation and growth is analyzed and associated with the residual stress distribution generated by both treatments. It is observed that both methods are complementary; cold expansion increases fatigue crack initiation life, while LSP reduces fatigue crack growth rate.

• 소성∙가공
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• 제16권8호
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• pp.575-581
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• 2007

The high dimensional accuracy of the cold forged part could be acquired by the accurate dimensional modification for the die, which is, the dimensional changes from the die through forged part to final part after heat treatment were considered. The experimental and FEM analysis are performed to investigate the dimensional changes from the die to final part on cold forged part, comparing with the machined gear. The dimension of forged part is compared with the die dimension at each stage, such as, machined die, cold forged part, and heat-treated-part. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the $DEFORM-3D^{TM}$. The analyzed residual stress of forged part is considered into the FE-analysis for heat treatment using the $DEFORM-HT^{TM}$. The effects of residual stress affected into the dimensional changes could be investigated by the FEA. Each residual stress of gears was measured practically by laser beam type measurement.