• Journal of Radiation Protection and Research
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• v.21 no.4
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• pp.273-284
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• 1996

Embryos and fetuses are more sensitive to various environmental agents than are adults or children. The biological effects such as intrauterine death and malformation are closely connected with prenatal exposure very various agents. The sensitivity of these embryonic/fetal effects depends on the stage of pregnancy. From the viewpoint of fetal development, embryonic and fetal stages can be divided into three stages : Preimplantation, organogenetic and fetal. Each stage corresponds to 0 to 4.5days, 4.5 to 13.5days, and 13.5days of gestation in mice, respectively. Many studies on the biologcal effects of mice irradiated by ${\gamma}-rays$ at various stages during organogenesis and fetal period have been performed. Based on these results, the dose-effect and dose-response relationships in malformations, intrauterine death, or retardation of the physical growth have been practically modeled by the ICRP(International Commission on Radiological Protection) and other international bodies for radiation protection. Many experimental studies on mice have made it clear that mice embryos in the preimplantation period have a higher sensitivity to radiation for lethal effects than the embryos/fetuses on other prenatal periods. However, no eratogenic effects of radiation at preimplantation stages of mice have been described in many textbooks. It has been believed that 'all or none action results' for radiation of mice during the preimplantation period were applied. The teratogenic and lethal effects during the preimplantation stage are one of the most important problems from the viewpoint of radiological protection, since the preimplantation stage is the period when the pregnancy itself is not noticed by a pregnant woman. There are many physical or chemical agents which affect embryos/fetuses in the environment. It is assumed that each agents indirectly effects a human. Then, a safety criterion on each agent is determined independently. The pregnant ICR mice on 2, 48, 72 or 96 hours post-conception (hpc), at which are preimplantation stage of embryos, were irradiated whole body Cesium-gamma radiation at doses of 0.1, 0.25, 0.5, 1.5, and 2.5 Gy with dose rate of 0.2 Gy/min. In the embryos from the fetuses from the mice irradiated at various period in preimplantation, embryonic/fetal mortalities, incidence of external gross malformation, fetal body weight and sex ratio were observed at day 18 of gestation. The sensitivity of embryonic mortalities in the mice irradiated at the stage of preimplantation were higher than those in the mice irradiated at the stage of organogenesis. And the more sensitive periods of preimplantation stage for embryonic death were 2 and 48 hpc, at which embryos were one cell and 4 to 7 cell stage, respectively. Many types of the external gross malformations such as exencephaly, cleft palate and anophthalmia were observed in the fetuses from the mice irradiated at 2, 72 and 96 hpc. However, no malformations were observed in the mice irradiated at 48 hpc, at which stage the embryos were about 6 cell stage precompacted embryos. So far, it is believed that the embryos on preimplantation stage are not susceptible to teratogens such as radiation and chemical agents. In this study, the sensitivity for external malformations in the fetuses from the mice irradiated at preimplantation were higher than those in the fetuses on stage of organogenesis.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.3
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• pp.139-148
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• 2006

• Journal of Life Science
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• v.19 no.5
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• pp.587-592
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• 2009

A dramatic morphological change of embryos occurs at peri-implantation. Maternal and embryonic cross-talk during this period, initiated by signals from embryo(s), provides signals for maternal recognition of pregnancy and establishing and maintaining the pregnancy. However, the cellular, biochemical and genetic processes that direct embryo remodeling in mammalian species are not well studied or understood. In order to identify potential genes responsible for morphological change and cross-talk between embryo and uterus, an initial EST analysis was performed. A catalog of expressed genes (Transcriptome) from the d12 peri-implanting porcine embryos was constructed. Six clones were chosen from the initial ESTs for elucidation of their expression patterns during embryogenesis in early pregnancy. A number of these genes demonstrated unique expression profiles in a tissue, cell-type, and temporal fashion, indicating dynamic regulation of embryonic and endometrial gene expressions at different stages of pregnancy. Cross-talk between the embryo and endometrium of the pregnant uterus has provided a suitable micro-environment for the embryo's rapid and dramatic morphological changing process at the peri-implantation stage.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.4
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• pp.237-243
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• 2006

Objective: The aim of this study was to evaluate the efficacy of frozen-thawed ET in poor prognosis patients such as the old age (38~44 years; OA group) and the patients who did not achieve clinical pregnancy with the first fresh ET cycle (non-pregnant patients; NP group). Methods: Laboratory and clinical data were collected from fresh and frozen-thawed ET cycles of OA and NP group. Controlled ovarian hyperstimulation (COH) and conventional insemination or ICSI, in vitro culture and ET were performed by routine procedures. Supernumerary embryos were frozen by the slow freezing method, and frozen embryos were thawed by the rapid thawing method. Embryo development, pregnancy and implantation rates were statistically analyzed by Student t-test and chi square test Results: Mean ages were similar between fresh ET ($40.0{\pm}1.8$ years, n=206) and frozen-thawed ET ($39.9{\pm}1.9$ years, n=69) cycles in OA group. However, the clinical pregnancy and implantation rate of subsequent frozen-thawed ET significantly higher than those of fresh ET cycles (29.0% and 11.2% vs. 16.5% and 7.0%, p<0.05). In NP group, there was no difference in the mean age between fresh ET ($31.2{\pm}2.3$ years, n=40) and frozen-thawed ET ($31.9{\pm}3.1$ years, n=119) in subsequent cycles. The clinical pregnancy and implantation rates were similar between the subsequent fresh ET (42.5% and 22.6%) and the frozen-thawed ET (40.3% and 18.8%). Conclusion: In old age patients, higher pregnancy rate of frozen-thawed ET compared to fresh ET cycles in this study. It may be related that better uterine environments for implantation in frozen-thawed ET cycles than that of non-physiological hormonal condition in uterus of fresh COH cycles.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.3
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• pp.197-205
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• 2007

Objective: This study evaluated the pregnancy and implantation rates in fresh IVF-ET cycles or frozen-thawed ET (F-ET) cycles based on serum estradiol concentrations of controlled ovarian hyperstimulation (COH). Methods: Clinical outcomes of 1,565 cycles of fresh IVF-ET with COH and 670 cycles of F-ET were retrospectively analyzed. Serum estradiol levels on the day of human chorionic gonadotropin (hCG) administration were categorized into Group-A (1,000$\sim$2,000 pg/ml), Group-B (2,000$\sim$3,000 pg/ml), Group-C (3,000$\sim$4,000 pg/ml) and Group-D (> 4,000 pg/ml). Clinical pregnancy (CPR), implantation (IR) and delivery rates (DR) were compared among four groups subdivided into younger (< 35 years) and older ($\geq$ 35 years) women. Statistical analysis was performed by Student's t-test and chi-square test. Results: Overall clinical outcomes with fresh IVF-ET and F-ET cycles were similar: 41.2% vs 44.8% of CPR, 18.8% vs 19.6% of JR, and 33.2% vs 34.5% of DR, respectively. There were no significant differences in the clinical outcomes of all four groups between fresh IVF-ET and F-ET cycles of younger women according to the estradiol levels. However, the clinical outcomes of F-ET cycles of older women in Group-D were significantly higher than those of fresh IVF-ET cycles (51.3% vs 25.0% of CPR*, 18.6% vs 9.9% of IR and 33.3% vs 19.4% of DR;* p<0.05). Conclusion: Our results demonstrated that supraphysiological levels of estradiol during COH in fresh IVF-ET cycles of older women ($\geq$ 35 years) may be detrimental to implantation environments of endometrium and clinical outcomes, which could be improved by F-ET cycles.

• Korean Journal of Animal Reproduction
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• v.20 no.4
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• pp.379-384
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• 1997

Superovulation with exogenous gonadotropins creates a spectrum of pre or periovulatory hormonal changes with subsequent detrimental effects on oocyte quality, fertilization, embryo development, implantation and maintenance of pregnancy. Our recent study determined potential roles for insulin-like growth factor-1 (IGF-1) in uterine environment regulation and preimplant tation in the rat. The evidence indicates that IGF-l may play an important role in the main tenance of a receptive uterine environment for embryonic development and the regulation of decidualization. Embryonic loss and failure of implantations following superovulation may be partially attributed to disturbances in uterine IGF-l action as observed in this study. We investigated the effects of superovulatory doses of gonadotropins on frequency of chromosomal a abnormalities of mouse embryos. Chromosome a analysis of mouse zygotes and 8- to 16-cell stage embryos from spontaneously ovulated, 5, 10, and l 15 lU pregnant mare serum gonadotropin (PMSG) superovulated mice was carried out. Aneuploidy, polyploidy and structural chrom- osomal abnormalities were detected among the four groups. However, only polyploidy was correlated with superovulation. In 10 and 15 IV PMSG treated groups, the rate of polypoidy was 2.9% and 10.5%, respectively. Furthermore, there was a dose reponse relationship between the PMSG dose and the incidence of embryonic p polyploidy (P

• Environmental Mutagens and Carcinogens
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• v.10 no.2
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• pp.119-126
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• 1990

본 최기형시험은 엘라스타제가 임신토끼와 태자에 미치는 영향을 조사할 목적으로 수행되었다. 시험은 임신된 New Zealand White 종의 토끼를 2개의 대조군 (제 1, 제 2대조군)과 3개의 투여군 (제 1, 제 2, 제 3투여군)으로 나누어 실시되었다. 제 1, 제 2, 제 3투여군에는 각각 엘라스타제 1, 2, 12, 120mg/kg을 임신 6일부터 18일까지 연일 경구투여하였으며, 같은 기간동안 제 1대조군과 제 2대조군에는 각각 10% skim milk 수용액과 ethylene thiourea 40mg/kg을 경구투여하였다. 임신 29일에 모든 모동물을 도살하여 모체와 태자를 검색하였다. 시험기간중 제 2대조군에서는 사료섭취량이 유의성있게 감소되었다 (P<0.01). 시험결과 황체수, 착상수, 생존태자수, 태자의 성비, 태자 및 태반중량에 있어서 각 군간 유의성있는 변화가 관찰되지 않았으며 태자의 외형검사, 애부장기 및 골격 검사에서도 군간 유의성있게 변화가 관찰되지 않았다. 이상의 결과로 미루어 본 시험에서 채택한 엘라스타제의 용량은 토기에 있어서 최기형 유발능이 없는 것으로 판단된다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.147-149
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• 2019

해수 온도의 상승과 해양 오염의 증가로 근래 국내 해안에서도 갯녹음이 확산되면서 바다숲이 축소되고 있다. 특히, 온난류의 유입에 의한 무절 석회조류의 난입과 해수에 함유 농도가 증가한 칼슘이 석출되고 해저 암반을 뒤덮어 해조류의 포자 활착 공간을 없애는 백화현상이 확산되면서 바다의 사막화 현상이 가속화되고 있다. 본 연구에서는 해조류의 포자가 빠르게 활착하여 안전하게 생장할 수 있는 공간을 제공하기 위한 새로운 방안으로, 먼저 육상에서 모판의 기능을 제공하여 해조류의 포자를 착상하여 성장시킨 후 해저로 이식하는 것으로 바다숲과 해안의 환경을 효과적으로 복원하기 위한 방안으로 다공성 기질 생태 플랫폼을 디자인하고 이의 특성 및 활용 방안을 제시하였다.

• Journal of Society of Preventive Korean Medicine
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• v.9 no.2
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• pp.59-75
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• 2005

The experiments were undertaken to evaluate the effects of Bosaengtang in pregnant rats and fetuses. Female Sprague-Dawley rats were orally administered with Bosaengtang at the dose of 5mg/kg/day for 20 days. Pregnant rats were sacrificed at the 20th day of gestation, and observed internal and reproductive organs. Fetuses were randomly selected and fixed in 95% ethanol. Fetuses were stained with alcian blue and alizarin red S, and observed skeletal malformations. The results obtained were as follows : Bosaengtang administered group showed higher maternal body weight than the control group, but both groups showed increase in weight. Bosaengtang administered group showed lower than the control group, and higher liver and kidney weight than the control group, but the differences were minimal. There were no significant changes between the control and treated group in blood chemistry values and hematological values but all the groups were within in normal ranges. There were no significant changes in the number of corpus luteum, implantation, live fetus and implantation rate, delivery rate, late resorption rate, sex ratio, but Bosaengtang administered group showed higher early resorption rate than control group. comparing the control and Bosaengtang group, neonatal body weight and the number of fetuses were increased in Bosaengtang group. The fetuses of dams treated with Oriental medicine didn't showed external malformation. Vertebral and sternal variations were observed in Bosaengtang group, but the differences were not apparent compared to the control group. The number of ribs, cervical, thoracic and lumbar vertebrae were normal. The number of sacral was similar and the number of caudal was increased. Fetuses showed significant difference in the number of caudal vertebrae. (P<0.01) From these results, we can carefully conclude that Bosaengtang showed beneficial effects on maternal body weight, early resorption rate, number of live fetus. There were no significant changes in organ weight, hematoscopy, reproduction organs. External malformation wasn't visible. Skeletal variations were showed in vertebrae and sternum but compared to the control group, these variations weren't much different.

• Journal of the KSME
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• v.35 no.9
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• pp.816-828
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• 1995

냉동공조용 열교환기의 종류, 특징, 기술개발 동향, 전망 등에 대해 요약한 결과를 정리하면 다 음과 같다. (1) 암모니아 냉매가 다시 각광을 받음에 따라 응축기의 형식도 크게 변하고 있다. 이러한 변화로 핀 튜브를 사용한 횡형, 금속용착형 플레이트 식, 플레이트 핀 식의 응축기들이 암모니아 용으로 적용되기 시작하고 있다. (2) 암모니아 냉동장치는 현재에도 많이 적용되고 있으나 대부분 중앙 집중식 천정증발기나 강관 제 유닛 쿨러를 사용하고 있다. 그러나 최근 기술의 발전과 더불어 알루미늄 관 알루미늄 핀 증발기가 개발됨에 따라 암모니아 냉매도 프레온 냉매와 마찬가지로 건식, 분산식으로 적용되게 되었으며 이 분야의 기술개발이 요청된다. (3) 열교환기의 연구 방향은 에너지 절약, 공간 절약에 기여하면서도 성능향상을 이룩할 수 있는 기술개발, 그리고 소음이 적은 기기 제조 기술이 요망된다. 또한, 착상에 대한 기술적 대책, 근 본적 대책에 대한 대비가 요망되며, 기존 냉매에 대한 대체 냉매용 최적 열교환기에 대한 적극적 연구가 요망된다. (4) 제한된 에너지 자원, 지구환경, 열악한 우리나라의 에너지 사정 등을 고려할 때 냉동공조용 열교환기의 성능 향상에 대한 국가와 일반 소비자들의 기대는 더욱 증가하리라 예상된다. 이들 요구를 만족시키기 위해서는 냉동공조용 열교환기의 성능 향상, 열교환기의 제작에 필요한 자 원의 절약, 생산성 향상, 설치장소와 관련한 효율적인 공간활용, 열교환기 자체 소음의 최소화 등의 방면에 착실한 연구 개발이 있어야 할 것이다.