• 열처리공학회지
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• 제10권1호
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• pp.1-9
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• 1997

The variation of the mechanical properties and the formation of retained austenite with heat treatment conditions in austempered Si bearing carbon steels has been investigated. In the case of a steel containing 0.35C-1.48Si-0.95Mn, it has been found that a feather shape bainite structure of lath are obtained under a isothermal treated condition at just below the Ms temperature, and the martensite, bainitic ferrite and retained austenite of second phase particles on the ferrite matrix for a isothermal treated steels after intercritical annealing are precipitated in a linked shape. The retained austenite with $2{\mu}m$ size induced as TRIP is found to increase with increasing the formation rate of retained austenite for the intercritical annealing and high Si containing steels. The tensile strength is increased as austempering temperature increases in all isothermal treatment temperature, whereas the elongation is shown to roughly decrease as the tensile strength increases. The values of tensile strength-elongation balance have showed a marked dependence upon the elongation rather than the tensile stregth, and their values are increased for high Si containing steels and intercritical annealing condition. The most optimum result has been shown to be the tensile stregth-elongation balance of $2882.4kgf/mm^2.%$ and the elongation of 33.3% for a "B" steel in the heat treating temperature range of $780{\sim}370^{\circ}C$.

• 고전문학과교육
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• 제15호
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• pp.191-243
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• 2008

The purpose of this paper is to develope the husband and wife epic test. The results of this paper are as follows. First, in the epic of dividing mate, , , , , etc, the essential item of diagnosis is qualification criteria of a mate. Second, in the epic of pushing mate, , , , , , etc, the essential item of diagnosis is mistrust about mate, Third, in the epic of recovering mate, , , , , , etc, the essential item of diagnosis is ability of recovering couple relationship, Fourth, in the epic of protecting mate, , , , , , etc, the essential item of diagnosis is sympathy for mate.

• Animal Bioscience
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• 제34권11호
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• pp.1839-1848
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• 2021

Objective: The objective of the present study was to investigate the comparative effects of dietary functional nutrients including glutamine (Gln), chromium picolinate (Cr picolinate), vitamin C (Vit C), betaine (Bet), and taurine (Tau) on growth performance, meat quality, immune responses, and stress biomarkers in broiler chickens raised under heat stress conditions. Methods: A total of 420 21-d-old Ross 308 male broiler chickens (initial body weight = 866±61.9 g) were randomly allotted to 1 of 7 treatment groups with 6 replicates. One group was kept under thermoneutral conditions and was fed a basal diet (PC, positive control). Other 6 groups were exposed to a cyclic heat stress condition. One of the 6 groups was fed the basal diet (NC, negative control), whereas 5 other groups were fed the basal diet supplemented with 0.5% Gln, 500 ppb Cr picolinate, 250 mg/kg Vit C, 0.2% Bet, or 1.0% Tau. The diets and water were provided ad libitum for 21 d. Results: Broiler chickens in NC group had decreased (p<0.05) growth performance and immune responses measured based on cutaneous basophil hypersensitivity (CBH), but increased (p<0.05) stress responses measured based on feather corticosterone concentrations and blood heterophil:lymphocyte than those in PC group. However, none of dietary functional nutrients had a positive effect on growth performance of broiler chickens. Dietary supplementation of 250 mg/kg Vit C improved (p<0.05) CBH responses of broiler chickens, but other functional nutrients had no such an improvement in CBH responses. All functional nutrients decreased (p<0.05) stress responses of broiler chickens. Conclusion: Functional nutrients including Gln, Cr picolinate, Vit C, Bet, and Tau at the supplemental levels used in this study decrease stress responses of broiler chickens to a relatively similar extent. However, this reduction in stress responses could not fully ameliorate decreased productive performance of broiler chickens raised under the current heat stress conditions.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1119-1126
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• 2021

Spacer grid with mixing vane had been widely used in nuclear reactor core. One of the main feather of spacer grid with mixing vane was that strong swirl flow was formed after the spacer grid. The swirl flow not only changed the bubble generation in the near wall field, but also affected the bubble behaviors in the center region of the subchannel. The interaction between bubble and the swirl flow was one of the basic phenomena for the two phase flow modeling in fuel assembly. To obatin better understanding on the bubble behaviors in swirl flow, full three dimension numerical simulations were conducted in the present paper. The swirl flow was assumed in the cylindral calculation domain. The bubble interface was captured by Volume Of Fluid (VOF) method. The properties of saturated water and steam at different pressure were applied in the simulation. The bubble trajectory, motion, shape and force were obtained based on the bubble parameters captured by VOF. The simulation cases in the present study included single bubble with different size, at different angular velocity conditions and at different pressure conditions. The results indicated that bubble migrated to the center in swirl flow with spiral motion type. The lateral migration was mainly related to shear stress magnitude and bubble size. The bubble moved toward the center with high velocity when the swirl magnitude was high. The largest bubble had the highest lateral migration velocity in the present study range. The effect of pressure was small when bubble size was the same. The prelimenery simulation result would be beneficial for better understanding complex two phase flow phenomena in fuel assembly with spacer grid.

• Journal of Veterinary Science
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• 제23권5호
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• pp.67.1-67.11
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• 2022

Background: Budgerigar fledgling disease polyomavirus (BFDV) is the pathogen that causes budgerigar fledgling disease in psittacine species. The clinical signs of PBFV infection include ascites, hepatitis, and crop stasis. BFDV is associated with a high mortality rate in nestling birds. In contrast, adult birds only have mild symptoms such as feather dystrophy. Objectives: This study aimed to determine the prevalence, genetic characteristics, and phylogenetic analysis of BFDV in pet parrots in Korea. Methods: Fecal and tissue samples were collected from 217 pet parrots from 10 veterinary hospitals including Chungbuk National University Veterinary Hospital. The molecular screening was performed using polymerase chain reaction (PCR) analysis of the small t/large T antigen gene segment. Full-length genome sequencing with the Sanger and phylogenetic analysis were performed on BFDV-positive samples. Results: The PCR results based on the small t/large T antigen gene marker indicated that BFDV DNA was present in 10 out of 217 screened samples. A whole-genome sequence was obtained from six strains and phylogenetic analysis revealed no significant relationship existed between the species and geographical locations amongst them. Conclusions: The prevalence of BFDV infection in South Korea is not high when compared to the prevalence of BFDV in other parts of the world, however, it has been reported sporadically in various species and geographic locations. The whole-genome analysis revealed 0.2%-0.3% variation in intragenomic homogeneity among the six strains analyzed. Korean strains are separately on the phylogenetic tree from their counterparts from China and Japan which might reflect the substantial genetic variation.

• 한국응용곤충학회지
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• 제61권4호
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• pp.623-631
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• 2022

깨알벌레과는 전세계적으로 약 100속, 1,000여 종이 알려져 있다. 깨알벌레들은 다양한 서식처에서 채집되며, 깃털 모양의 날개와 작은 크기로 쉽게 구분된다. 이 중 Acrotrichis속은 깨알벌레과의 약 4분의 1을 차지하나, 국내에서는 Acrotrichis lewisii (Matthews, 1884b)만이 2020년에 처음으로 기록되었다. 본 연구에서는 전국 농경지 생물상 변동조사 중 제주에서 채집된 A. thoracica (Waltl, 1838)와 A. grandicollis (Mannerheim, 1844)를 국내에 처음으로 보고한다. 이 두 종의 외형과 세부 사진, 분포도 그리고 한국산 Acrotrichis속의 분류키를 함께 제공한다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2001년도 추계학술대회
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• pp.39-45
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• 2001

Extremophiles are unique microorganisms that are adapted to survive in ecological niches such as high or low temperatures, extremes of pH, high salt concentrations and high pressure. These unusual microorganisms have unique biochemical features which can be exploited for use in the biotechnological industries. Due to the high biodiversity of extremophilic archaea and bacteria and their existence in various biotopes a variety of biocatalysts with different physicochemical properties have been discovered. The extreme molecular stability of their enzymes, membranes and the synthesis of unique organic compounds and polymers make extremophiles interesting candidates for basic and applied research. Some of the enzymes from extremophiles, especially hyperthermophilic marine microorganisms (growth above $85^{\circ}C$), have already been purified in our laboratory. These include the enzyme systems from Pyrococcus, Pyrodictium, Thermococcus and Thermotoga sp. that are involved in polysacharide modification and protein bioconversion. Only recently, the genome of the thermoalkaliphilic strain. Anaerobranca gottschalkii has been completely sequenced providing a unique resource of novel biocatalysts that are active at high temperature and pH. The gene encoding the branching enzyme from this organism was cloned and expressed in a mesophilic host and finally characterized. A novel glucoamylase was purified from an aerobic archaeon which shows optimal activity at $90^{\circ}C$ and pH 2.0. This thermoacidophilic archaeon Picrophilus oshimae grows optimally at pH 0.7 and $60^{\circ}C$. Furthermore, we were able to detect thermoactive proteases from two anaerobic isolates which are able to hydrolyze feather keratin completely at $80^{\circ}C$ forming amino acids and peptides. In addition, new marine psychrophilic isolates will be presented that are able to secrete enzymes such as lipases, proteases and amylases possessing high activity below the freezing point of water.

• 한국식품저장유통학회지
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• 제31권1호
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• pp.1-14
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• 2024

The utilization of coatings composed of bio-based materials in the processing and preservation of meat presents an environmentally conscious, secure, cost-effective, and superior method for prolonging the storage life of meat while also preserving its nutritional value. In this study, changes in physical, chemical, and microbiological characteristics of freshly cut beef coated with distilled water (control) and keratin-starch composites (K-S) functionalized with 0.0-, 0.2-, 0.6-, and 1.0-mL avocado peel polyphenolic-rich extract (APPPE) kept at 4℃ for 12 days were evaluated periodically at 3-day interval using standard techniques. Keratin was extracted from waste feathers, while starch was obtained from ginger rhizomes. Following a 12-day storage period, beef coated with APPPE-enriched K-S composites exhibited a significant (p<0.05) improvement in shelf life by minimizing deteriorative changes in pH and color (as determined by metmyoglobin level) in addition to inhibiting oxidative changes in lipids (as determined by TBARS level) and proteins (protein carbonyl level) in comparison to control and K-S composite without APPPE. Furthermore, microbial growth was significantly (p<0.05) suppressed in meat coated with K-S composite functionalized with APE at 0.6 and 1.0 mL compared to the control. The study suggested that APPPE-enriched K-S composite could offer an eco-friendly and safe food preservation technique for fresh meat.

• 한국환경생태학회지
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• 제22권4호
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• pp.435-441
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• 2008

본 연구는 사육환경 조건에서 참수리(Haliaeetus pelagicus)의 연령에 따른 꼬리깃의 변화 과정을 조사하기 위해서 2000년 11월부터 2006년 7월까지 약 6년간 경성대학교 조류연구소에서 조사한 것이다. 꼬리깃의 깃갈이 시기는 보통 7월부터 시작해 익년 4월까지 진행되었으며, 1회의 깃갈이에 모든 깃이 교체되었다. 보통 12월 이전에 2/3 정도가 교체되었으며, 나머지는 익년 4월까지 모두 교체되었는데, 겨울동안에도 깃갈이가 지속되었다. 꼬리깃의 총 개수는 14개로써 깃갈이는 번갈아가면서 단계적으로 이루어졌고 암컷은 4단계, 수컷은 3단계로 진행되었는데 각 단계마다 좌.우측 깃이 대칭적으로 진행되는 것이 특징이었고 한 단계의 성장이 거의 끝날 때 다음단계가 시작되었다. 유조 꼬리깃의 빛깔은 흰색 바탕에 검은색 얼룩이 산재해 있고 깃의 끝부분에는 불규칙적인 검은색 띠가 있었는데 1-3세대깃(1-3차 여름깃)까지는 빛깔의 차이가 극히 적어 꼬리깃으로만 연령을 파악하기는 어려웠다. 또한 개체별로 나타나는 검은색 얼룩무늬의 양도 다르다는 것을 고려했다. 4세대 깃(4차 여름깃)은 3세대 깃에 비해서 큰 차이를 보이며 흰색깃에 약간의 검은색 얼룩만 존재하였다. 4차 깃갈이가 끝난 5세대 깃(5차 여름깃)은 순 백색의 완전한 성조 꼬리깃의 빛깔을 갖추었다. 야외에서 참수리를 관찰하였을 때 3세대 깃(3차 여름깃)까지는 연령을 판단하는데 신중한 검토가 필요하며 꼬리깃 외에 다른 부위의 깃 변화도 함께 관찰해야 할 것으로 생각한다.

• Composites Research
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• 제12권4호
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• pp.71-78
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• 1999

방향족 아민 경화제의 벤젠링 사이의 관능기 변화가 반응특성, 기계적특성 및 열적특성에 미치는 영향을 고찰하기 위하여 양쪽 말단기에 에폭시기를 가지는 대표적 범용 에폭시수지인 DGEBA (diglycidylether of bisphenolA)와 방향족아민 경화제 diaminodiphenyl methane (DDM), diaminodiphenyl sulphone(DDS) 각각을 1:1의 당량비로 혼합하여 동일한 조건으로 경화하였다. 반응특성, 열 안정성, 에폭사이드기의 전환율, shrinkage(%), 유리전이온도와 선팽창계수, 기계적특성 그리고 굴곡 파단특성을 알아보기 위하여 각각 DSC 분석, TGA 분석, FT-IR 분석, 밀도측정, TMA 분석, 인장시험과 3점 굴곡시험, 광학현미경 시험을 행하였다. 그 결과, 에폭시수지 경화물의 분석, 밀도측정, TMA 분석, 인장시험과 3점 굴곡시험, 광학현미경 시험을 행하였다. 그 결과, 에폭시수지 경화물의 특성은 경화제의 벤젠링 사이의 관능기 구조에 따라 매우 큰 영향을 받았다. 즉, 벤젠링 사이에 길이가 길고 bulky한 술폰기를 포함한 DDS는 epoxiderl의 전환율, shrinkage(%), 유리전이온도, 인장탄성율, 인장강도, 굴곡탄성율 및 굴곡강도의 값이 길이가 짧고 compact한 메틸기를 가지는 DDM 경화물계 보다 높게 나타났지만, 최대발열온도, 열안정성, 선팽창계수의 값은 낮게 나타냈다. 이것은 술폰기의 강한 전기음성도와 메틸기의 전기 양성적인 repulsive한 성질의 차이와 epoxide group의 전환율의 영향인 것으로 판단된다. 굴곡 파단면의 관찰 결과는 DDM경화물계의 feather like structure의 각개 grain의 크기가 DDS 경화물계 보다 작은 것을 확연하게 보여준다.gG1 항체 합성은 spleen B cell과는 달리 TGF-$\beta$3에 의해 증가하였다. 본 실험의 결과는 전반적으로 TGF-$\beta$3가 TGF-$\beta$1과 비슷한 정도로 마우스 B cell의 항체합성에 영향을 미침을 보여준다. 그렇지만, 생체 내에서TGF-$\beta$3의 발현조절이 TGF-$\beta$1과 다를 것으로 예상됨으로 과연 TGF-$\beta$3가 B cell 분화에서 중요한 조절인자로 작용할지는 좀 더 연구되어야 할 것이다.적을 볼 때 적극적으로 수술에 임하는 것이 바람직하다고 사료된다.나타나 이의 규명을 위해서는 향후 p53 단백의 유전자 변이와 두 단백의 발현과 환자의 생존율과의 상관관계에 대한 연 구가 요할 것으로 사료된다.을 줄이기 위한 대책이 도움이 될 것으로 사료된다.4.00$\pm$0.14, 2.50$\pm$ 0.31, 4.02$\pm$0.70으로 기준(1.84$\pm$0.21)에 비하여 IP군과 10 mM 칼슘 전처치군에서 유의하게 증가하였다 (p<0.05). 그러나 허혈대조군에서는 두 분획 모두 기준선과 비교하여 큰 차이가 없었다. 결론: 이상으로 적출 관류 토끼심장에서 장시간 동안의 허혈전 높은 농도의 칼슘으로 전처치하면 허혈후 재관류시 심근기능의 회 복증가는 기대하기 어려우나 IP와 유사한 심근괴사 범위 감소효과가 있으며 이러한 효과는 아마도 칼슘의 매개에 따라 PKC활성화가 일어남으로써 나타나는 것으로 생각된다. 점을 함께 고려하면 그룹 B에서의 더 큰 증폭 효과가 광배근의 활성도 및 수축력의 차이로부터 기인한다고 평가할