• 소성∙가공
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• 제11권3호
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• pp.255-261
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• 2002

The grain size of 7010 Al alloy was refined to submicrometer level by using equal channel angular pressing (ECAP) and additional warm rolling. The mechanisms of grain refinement in ECAP process were fragmentation of coarse grain to ultra fine subgrains after a few passes and continuous recrystallization of the subgrains with the increase o( passes. Because of ultrafine grain size, essentially low temperature and high strain rate superplasticity was observed after ECAP process and warm rolling to form a sheet metal. The maximum elongation of 700% was obtained for an ECA pressed specimen after IS passes without warm rolling at $450^{\circ}C$ with strain rate of 5x$10^{-3}$/sec.

• 한국환경복원기술학회지
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• 제17권2호
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• pp.125-136
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• 2014

Urban Green Area has ecologically deteriorated along with quantitative loss, being developed as a dot itself rather than connected to forests and green networks around the park. The present study aims to propose a connected plan on Urban Ecological Network establishment through 'assessment of the connectivity of the entire urban parks' in accordance with distance of forest and river and 'assessment of trends in connection fragmentation of urban parks' in accordance with the past change of forest and river. According to the result of this study, criteria based on previous research was "directly linked type is less than 300m, conceptually linked type is between 300m to 1km, the isolated type is greater than 1km". And the result of 'assessment of the connectivity of the entire urban parks' is analyzed as the rate of park and green network, 41.7% in Suwon, 80.0% in Seongnam, 88.9% in Namyangju on the basis of office and field investigation. Also, according to the result of 'assessment of trends in connection fragmentation of urban parks', consideration for connection to the original forest is insufficient.

• 한국정밀공학회지
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• 제17권2호
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• pp.43-50
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• 2000

A CBN wheel was used for the highly efficient and precision grinding of the mold material(STD11). The grinding form accuracy by a CBN wheel is very excellent due to its low wheel wear, but grinding fragments resemble fine powders rather chips. A fine powders by this fragmentation can easily get attached to the wheel surface and therefore causing a loading. In order to prevent this fragmentation phenomena, the alumina stick is use to processing. Because the dressing with alumina stick should be interrupted for a processing, the automation of the processing and high productivity was very difficult. The investigation on the effect of Ultrasonic In-Process Dressing(ULID) on the grinding characteristics focuses in this Paper. This ULID method is that ultrasonic vibration in my Position of wheel is used to remove impurities on the wheel surface. Finally, the rate of surface roughness change in grinding by the ULID method was less than grinding without ultrasonic vibration. Loading phenomena by the ULID method were more prevented than grinding without ultrasonic vibration.

• 화약ㆍ발파
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• 제34권2호
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• pp.10-17
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• 2016

발파작업을 위해 필요한 천공작업은 발파의 효과를 좌우하는 중요한 부분으로 인식되고 있다. 발파를 위한 천공작업 시 발생되는 천공오차는 잔류공 및 여굴 발생, 불균질한 파쇄입도 등 발파효율 저하요인들을 발생시킬 수 있다. 정확한 천공을 위해 자동 천공 점보드릴을 도입하였다. 그 결과 공간격, 저항선의 천공오차율 0~2.6%로 미미하게 나타났으며 이로 인하여 90%이상의 굴진율, 전체 굴착량 대비 여굴량 4.3%, 50cm 이하 파쇄석 비율 89%~95% 등 발파효과가 향상된 것을 확인하였고 이로 인해 발파 Cycle time을 절감할 수 있을 것으로 판단된다.

• 한국식품영양과학회지
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• 제32권5호
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• pp.689-694
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• 2003

꿀벌의 벌집에서 채집되어지는 프로폴리스는 항염증, 항암성 등의 민간의학으로 사용되어져 왔다. 이러한 프로폴리스를 이용하여 총당에 대한 포도당 함량(0~100%), 에탄올 농도(20~100%) 및 에탄올 용액 분무량 (6~10%)의 비율로 혼합하여 세립형성에 따른 수율, 교반에 의한 분쇄율 및 관능적 특성의 변화를 검토하였다. 수율의 경우 에탄올 함량이 감소할수록 수율이 높게 나타났으며, 분쇄율의 경우 에탄올 함량이 증가할수록 감소하였다 색, 향, 맛, 입안에서의 느낌 및 전반적인 기호도에 있어서는 총당에 대한 포도당의 함량, 에탄올 농도 및 에탄올 함량 모두에 영향을 받는 것으로 나타났으며, 전반적인 기호도는 총당에 대한 포도당 함량 47.94%, 에탄올 농도 56.45%및 에탄올 용액 분무량 8.04%일 때 관능적으로 가장 우수한 6.90의 평점이 나타났다.

• 한국식품저장유통학회지
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• 제20권1호
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• pp.62-68
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• 2013

동결건조 로얄제리를 이용하여 세립차를 제조하고자 가공특성을 조사하였다. 동결건조 로얄제리를 이용하여 총당에 대한 포도당 함량($X_1$, 0~100%), 에탄올 농도($X_2$, 75~95%) 및 에탄올 용액 분무량($X_3$, 8~12%)의 비율로 혼합하여 세립형성에 따른 수율, 교반에 의한 분쇄율 및 관능적 특성의 최적조건을 반응표면분석을 통하여 조사하였다. 최대 수율은 총당에 대한 포도당 함량 59.30%, 알콜 농도 88,64% 및 알콜 용액 분무량 11.83%일 때 89.99%로 높게 나타내었다. 교반에 의한 최소 분쇄율은 총당에 대한 포도당 함량 22.35%, 알콜 농도 77.21% 및 알콜 용액 분무량 10.59%에서 0.82%로 낮게 나타내었다. 전반적인 기호도에 대한 최대 관능평점은 총당에 대한 포도당 함량 31.81%, 알콜 농도 93.96% 및 알콜 용액 분무량 10.51%에서 7.45로 나타났다.

• Journal of Nutrition and Health
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• 제41권1호
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• pp.22-30
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• 2008

사철쑥 (Artemisia capillaris Thunberg)이 암세포의 세포고사에 미치는 영향을 보기 위하여 인체 자국경부 상피암 세포주인 HeLa 세포를 이용하여 사철쑥의 메탄올, 에틸아세테이트, 부탄올 추출물의 농도를 각각 0, 100, 500, 1,000 및 $2,000{\mu}g/ml$로 처리하여 세포활성도, 세포형태 변화, DNA분절, DNA 함량을 알아보았다. 세포활성도는 사철쑥의 메탄올, 에틸아세테이트 추출물이 농도에 비례하여 HeLa세포생존율을 감소시켰지만 부탄올 추출물에서는 그 정도가 약하였고 물 추출물에서는 거의 관찰되지 않았다. 사철쑥의 메탄올, 에틸아세테이트, 부탄올과 물 추출물은 각 추출물의 농도에 의존적으로 배양된 HeLa 세포에 세포부착을 방해하고 세포막의 blobbing 및 핵의 분절화 등 세포고사의 특징들을 나타냈다. 사다리형 DNA 분절현상은 사철쑥의 메탄올 추출물 $1,000{\mu}g/ml$, $2,000{\mu}g/ml$ 처리군에서 관찰되었다. 유세포분석기 (FACS)를 이용하여 측정한 고사세포의 DNA 함량은 메탄올과 에틸아세테이트, 부탄올 추출물이 농도 의존적으로 증가하였다. 이상의 결과는 사철쑥이 암세포의 세포고사를 증가시킴으로서 암 억제 작용이 있을 것을 시사해 준다고 할 수 있다.

• Clinical and Experimental Reproductive Medicine
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• 제44권3호
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• pp.132-140
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• 2017

Objective: Correlations between semen parameters and sperm DNA fragmentation index (DFI) were investigated to identify characteristics of sperm without DNA damage that could be used in selecting sperm for intracytoplasmic sperm injection (ICSI). Pregnancy outcomes were compared to determine whether in vitro fertilization (IVF) or ICSI is a better choice for patients who have sperm with a high-DFI. Methods: Semen analysis was carried out in 388 patients who visited our IVF center for the first time to investigate correlations between sperm DFI and semen parameters. In addition, 1,102 IVF cycles in 867 patients were carried out in the present study; 921 cycles in the low-DFI group (DFI < 30%) and 181 cycles in the high-DFI group ($DFI{\geq}30%$). Both the low- and high-DFI groups were subdivided into IVF and ICSI cycle groups. Results: Sperm DFI showed significant inverse correlations with sperm motility (r = -0.435, p< 0.001) and morphology (r = -0.153, p< 0.05). Sperm DFI also showed significant correlations with rapid motility (r = -0.436, p< 0.001), and the kinetic parameters of average-path velocity (r = -0.403) and linearity (r = -0.412). Although there was no significant difference in the pregnancy rates between IVF (48.6%) and ICSI (44.8%) in the low-DFI group, the pregnancy rate of ICSI cycles (44.8%, p< 0.05) was significantly higher than IVF cycles (25.0%) in the high-DFI group. No significant difference was observed in the abortion rates between the low-DFI (52 of 921, 5.6%) and high-DFI groups (7 of 181, 3.8%). Conclusion: ICSI is a better choice than IVF for improving the pregnancy outcomes of patients who have sperm with a high DFI.

• Computers and Concrete
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• 제15권4호
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• pp.515-545
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• 2015

The paper presents results of FE simulations of the strain-rate sensitive concrete behaviour under dynamic loading at the macroscopic level. To take the loading velocity effect into account, viscosity, stress modifications and inertial effects were included into a rate-independent elasto-plastic formulation. In addition, a decrease of the material stiffness was considered for a very high loading velocity to simulate fragmentation. In order to ensure the mesh-independence and to properly reproduce strain localization in the entire range of loading velocities, a constitutive formulation was enhanced by a characteristic length of micro-structure using a non-local theory. Numerical results were compared with corresponding laboratory tests and available analytical formulae.

• Clinical and Experimental Reproductive Medicine
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• 제26권1호
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• pp.55-65
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• 1999

There have been many reports to date regarding the role of GnRH as a local regulatory factor of ovarian function as studies of human and rat ovaries revealed GnRH and its receptor. In recent studies it has been shown that GnRH directly causes apoptosis in the granulosa cells of the rat ovary, and such results leads to the suggestion that the use of GnRH agonist for more stable long term ovarian hyperstimulation in human IVF-ET programs causes granulosa cell apoptosis which may lead to follicular atresia. Therefore this study attempts to determine if granulosa-luteal cell apoptosis occurs in patients during IVF-ET programs in which GnRH agonist is employed for ovarian hyperstimulation. The quality of oocyte-cumulus complexes obtained during ovum pickup procedures were assessed morphologically and then the fertilization rate and developmental rate was determined. Apoptotic cells among the granulosa-luteal cells obtained during the same procedure were observed after staining with Hematoxylin-eosin. The fragmentation degree of DNA extracted from granulosa-luteal cells was determined and comparatively analyzed. There was no difference in the average age of the patients, the number of oocytes retrieved, and fertilization and developmental rates between the FSH/hMG group and GnRH-long group. There was also no difference in the apoptosis rate and pyknosis rate in the granulosa-luteal cells between the two groups. However, when the oocyte-cumulus complexes were morphoogically divided into the healthy group and atretic group without regard for the method of hyperstimulation, the results showed that the number of oocytes obtained averaged $11.09{\pm}8.75\;and\;10.33{\pm}4.53$ per cycle, respectively, showing no significant difference, but the fertilization rate (77.05%, 56.99%, respectively, p<0.01) and developmental rate (65.96%, 41.51%, respectively, p<0.01) was significantly increased in the healthy group when compared to the atretic group. The degree of apoptosis in the granulosa-luteal cells showed that in the healthy group it was 2.25% which was not significantly different from the atretic group (2.77%), but the pyknosis rate in the atretic group (27.81%) was significantly higher compared to the healthy group (11.35%, p<0.01). The quantity of DNA fragmentation in the FSH/hMG group was 32.22%, while in the GnRH-long group it was 34.27%, showing no significant difference. On the other hand the degree of DNA fragmentation was 39.05% and 11.83% in the healthy group and atretic group, respectively, showing significantly higher increase in the atretic group (p<0.01). The above results suggest that death of granulosa-luteal cells according to the state of the oocyte-cumulus complex is more related to pyknosis rather than apoptosis. Also, the GnRH agonist used in ovarian hyperstimulation does not seem to directly affect the apoptosis of retrieved oocytes and granulosa-luteal cells, and which is thought to be due to the suppression of the apoptogenic effect of GnRH agonist as a result of the high doses of FSH administered.