• 열처리공학회지
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• 제7권1호
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• pp.53-60
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• 1994

Austenite formation and Low temperatures mechanical properties of HSLA steel of different starting structures have been studied by intercritical annealing(IA). The different starting structures are: ferrite+pearlite(FP1), martensite(M1), cold worked ferrite+pearlite(FP2) and cold worked martensite(M2). In most cases tensile strength and elongation was increased by decreasing the testing temperatures regardless of the IA time. Tensile strength of the cold worked starting structures was higher than that of the non-cold worked starting structures. However not any noticeable difference in elongation was found between two cases. Low temperatures impact properties were affected by the starting structures. Charpy V-notch impact transition temperatures of the M-starting structures were around $-40^{\circ}C$, and those of the FP starting structures were around $-10^{\circ}C$. Impact energy was lower in the cold worked specimens than in the non-cold worked specimens at the same starting structures. DP structure obtained from the M-starting structure has shown superior low temperatures mechanical properties than the DP structure obtained from the FP-starting structure.

• 한국식품조리과학회지
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• 제23권1호통권97호
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• pp.78-82
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• 2007

Yulmoo Kimchi becomes sour without carbonated taste when ripened at room temperature after being placed under cold temperature. The carbonated taste of Kimchi is reported to come from the hetero lactic fermentation of Leuconostoc strains. Yulmoo extract was made with methanol and added to four lactic bacteria strains originating from kimchi. The bacteria were also subjected to $1^{\circ}C$ for 24 hours as a cold shock treatment. after which Leuconostoc mesenteroide subsp. dextranicum KCCM 40708, Lactobacillus brevis KCTC 3102, Lactobacillus plantarum KCTC 3108, and Leuconostoc lactics KCTC 3528 strains showed a growth inhibition with the addition of Yulmoo extract at the concentration of 250-4,000 ppm. Leuconostoc mesenteroide subsp. dextranicum KCCM 40708, Lactobacillus brevis KCTC 3102, Lactobacillus plantarum KCTC 3108, and Leuconostoc lactics KCTC 3528, a strains appearing at the early stage of Kimchi fermentation, showed a higher growth inhibition following Yulmoo treatment in combination with the cold shock.

• 열처리공학회지
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• 제35권4호
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• pp.211-219
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• 2022

It is known that superplastic materials with ultrafine grains have high elongation mainly due to grain boundary sliding. Therefore, in the present study we examined the influence of grain refinement, caused by a repetitive cold rolling and annealing process, on both superplastic elongation and superplastic deformation mechanism. The cold rolling and annealing process was repetitively applied up to 4 times using Fe-10Mn-3.5Si alloy. High-temperature tensile tests were conducted at 763 K with an initial strain rate of 1 × 10^-3 s^-1 using the specimens. The superplastic elongation increased with the number of the repetitive cold rolling and annealing process; in particular, the 4 cycled specimen exhibited the highest elongation of 372%. The primary deformation mechanism of all specimens was grain boundary sliding between recrystallized α-ferrite and reverted γ-austenite grains. The main reason for the increase in elongation with the number of the repetitive cold rolling and annealing process was the increase in fractions of fine recrystallized α-ferrite and reverted γ-austenite grains, which undergo grain boundary sliding.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2002년도 춘계학술발표회 초록집
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• pp.39-39
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• 2002

In order to improve wear and fatigue resistance of the structural materials, especially cold work roller for 304 stainless steel, an eco-super-finishing and surface hardening treatment using ultrasonic vibration energy was developed and applied to the SKD-ll roller. The eco-super-finishing machine was designed and fabricated by DesignMecha Co, by its own technology. It was observed that the surface roughness, hardness and residual stress were changed from $Ra{\;}={\;}O.25\mu\textrm{m}$, Hv=710 and ${\sigma}$={\;}+400{\;}MPa{\;}to{\;}Ra{\;}={\;}0.165\mu\textrm{m}$, Hv = 1200 and ${\sigma}=-610$ MPa after 20 KHz micro-cold forging, which means almost equal to the 300 % improvement of life-time.

• Journal of Ecology and Environment
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• 제34권3호
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• pp.251-257
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• 2011

The purpose of this study was to investigate the acclimation responses of Tamarix chinensis to cold stress. We evaluated the acclimation responses by measuring biomass, daily elongation rate, chlorophyll content, and total soluble carbohydrate content. The plant samples comprised leaves from seedlings of 2 different ages (8 and 12 weeks); the leaves were collected 0, 2, and 4 weeks after cold treatment. We found that the cold-treated samples showed reduced daily elongation rates and chlorophyll content. Further, these samples showed more than 8-fold increase in the total soluble carbohydrate content. However, the seedling ages did not have a significant influence on the growth of cold-treated seedlings. On the basis of these findings, we can conclude that T. chinensis seedlings aged less than 1 year old show acclimation to cold stress by accumulating soluble carbohydrates. This study may help us understand how T. chinensis seedlings acclimatize to their first cold season.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.603-608
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• 2001

Recently, cold expansion of fastener holes is commonly used in the aerospace industry to increase the fatigue endurance of airframes. Cold expansion process is used as the retardation of crack initiation in the hole. This treatment leads to an improvement of fatigue behavior due to the compressive residual stresses developed on the hole surface. The residual stress profile depends on the cold expansion ratio. In the present paper, it is shown that residual stress is redistributed due to the application of cold expansion process for CT specimen. It is further shown that residual stress increases in proportion to cold expansion ratio. It is thought that crack growth rate increases as cold expansion ratio.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.141-144
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• 2002

This study presents the enhancement of forgeability of SNCM522H materials. Target parts are output shaft(OP shaft) used as components of power train for automobiles. To carry out cold forging process of OP shaft by 1 pass instead of existing 2 pass process, studies in terms of process design and heat treatment were performed. To introduce the new process, Finite element Method are accomplished, and to verify the validity of proposed heat treatment cycle, several experiments(Hardness test, Observation of optical microstructures, tensile test) are carried out.

• 소성∙가공
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• 제7권6호
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• pp.530-538
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• 1998

Elimination of the heat treatment process is very important in automation of metal forming since controlling heat treatment by computer has many difficulties and it has bottle neck problem. non-heat-treated steels materials which are not in need of heat treatment have been developed for cold forging. However to apply non-heat-treated steel to structural parts. it is necessary to prove reliability of mechanical properties. In order to define the reliability of mechanical properties we have investigated microstructure, hardness, the tensile strength compressive strength and tensile fatigue strength for both steels. Considering the results of high cycle fatigue test for both specimen the characteristics of non-heat-treated steel are decided on the yield strength, It has same tendency for heat-treated steel. Therefore non-heat-treated steel which has the appropriate yield strength may be applied in cold forging.

• 동의생리병리학회지
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• 제23권6호
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• pp.1226-1233
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• 2009

Common cold occurs frequently and occupies an important position in medical treatment however obvious treatment is not suggested. There has been no agreement of pattern identification for common cold in oriental medicine. The purpose of this study is to develop a standard instrument of pattern identification for common cold which will be applied to clinical research. The items and structure of the instrument were based on review of published literature. The advisor committee on this study was organized by 9 oriental respiratory internal medicine professors of 11 oriental medical colleges nationwide. The experts attended 3 consultation meetings and discussed developing the instrument, and we also took professional advices by e-mail. The results were as follows; First, we divided the pattern identification of common cold into nine pattern: Wind-cold type, Wind-heat type, Contain summerheat type, Contain dampness type, Qi deficiency type, Blood deficiency type, Yang deficiency type, Yin deficiency type, Influenza. Second, we got the mean weights to each symptom of nine pattern identification which had been scored on a 5-point scale - ranging from 0 to 4 by the 9 experts. Third, we made out the Korean instrument of the pattern identification for common cold. It was composed self reporting questionnaire and researcher reporting questionnaire. Though this study is not proved about validity, reliability, the instrument of pattern identification for common cold is meaningful and expected to be applied to the subsequent research. And also, we hope to improve the instrument and make up for this study through various research and discussion.

• 한국작물학회지
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• 제37권3호
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• pp.257-263
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• 1992

GA$_3$ 농도 및 저온처리 기간이 보리의 춘화처리효과에 미치는 영향을 조사하고자, 추파성 정도가 IV인 올보리를 공시하여 출수후 13 및 20일이 경과한 미숙배를 GA$_3$농도별로 B$_{5}$배지에 치상하여 저온처리한 후 온도 20/15$^{\circ}C$, 14시간 일장으로 온냉조절실에 이식재배하여 실험한 결과는 다음과 같다. 1. 미숙배의 생육은 출수후 13일배 보다 20일배가 양호하여 발아율 및 유묘장은 증가하였고, 평균발아일수는 감소하였는데, GA$_3$1 및 10ppm이 효과가 좋았다. 2. GA$_3$농도가 증가할수록 상엽전개 및 출수일수가 단축되었으며, 춘화처리에 효과가 높은 GA$_3$농도는 1,10ppm이었고 GA$_3$와 저온처리가 병행될 때 춘화처리효과가 높았다. 3. GA$_3$ 처리에 따른 상엽전개일수 단축 효과는 3주 저온처리의 GA$_3$무처리구보다 2주 저온처리의 GA$_3$1,10ppm에서 각각 3, 16일 단축되었고, 3주저온처리의 1ppm에서 18일, 10ppm에서 20일 단축되었다. 4. 간장, 수장 및 일수립수는 공히 3주 저농처리에 GA$_3$ 10ppm 처리가 최소치를 보였는데, 실제육종상 중요한 일수립수의 확보는 충분할 것으로 보였다. 5. GA$_3$농도와 주요 형질과의 상관은 1주 저온처리시 각 형질들과 모두 상관 관계가 인정되지 않았으나, 2주 저온처리에서는 고도의 부상관이 인정되었고, 3주 저온처리에서는 출수일수를 제외한 모든 형질이 부의 상관이 있었다. 6. 저온처리 기간과 주요 형질들과의 상관은 GA$_3$무처리시 간장만 유의적인 부의 상관이 있었고, 기지 상관이 없었으며 GA$_3$1, 10ppm 처리시 모든 형질이 고도의 부상관이 있었다.다.