• Journal of Embryo Transfer
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• v.21 no.3
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• pp.255-262
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• 2006

The purpose of this study is to investigate the effects of vitrification in open pulled straws (OPS) methods on in vitro survival ability of porcine embryos. For in vitro maturation of immature oocytes, the porcine ovaries were collected from local slaughter-house. The cumulus-oocytes complexes were aspirated from 2 to 6 mm follicles. The collected oocytes were cultured for in vitro maturation in NCSU-23 medium with 5 mM hypotaurine, 0.57 mM cysteine, 10% porcine follicle fluid, 10 IU/ml PMSG and 10 IU/ml hCG for $21{\sim}22$ hrs. Then, the oocytes were more cultured $21{\sim}22$ hrs in vitro maturation in medium removed hormones. The frozen-thawed spermatozoa were washed by centrifugation 2 times for 10 min at 1,500 rpm in D-PBS with 5.56 mM glucose, 0.33 mM Na-pyruvate, 100 IU/ml penicillin, $100 {\mu}g/ml$ streptomycin and 4 mg/ml BSA. The fertilization medium used mTBM with 2 mM caffeine and 2 mg/ml BSA and adjusted to a pH of 7.2 to 7.4. The final concentration of spermatozoa was adjusted to $2.5{\times}10^6$cells/ml motile sperm during fertilization in vitro. At 8 hrs after insemination, the oocytes were transferred into NCSU-23 medium with 5.0 mM hypotaurine, 4 mg/ml BSA and 10 ng/ml EGF and cultured for 7 days. When the blastocysts of different stages were frozen-thawed by OPS methods, the proportions of embryos with normal morphology were significantly (p<0.05) higher in embryos frozen-thawed at expanded blastocyst stage (38.9%) than in early blastocyst stage (28.3%). On the other hand, the proportions of embryos damaged after frozen-thawing were significantly (p<0.05) higher in embryos frozen at early blastocyst stages than in expanded blastocyst stage. In another experiment, the normal embryos morphology after frozen- thawing were further cultured for 48 hrs. After culture, the proportions of embryos hatched were 6.7, 20.0 and 33.3% for embryos frozen-thawed at early blastocyst, mid-blastocyst and expanded blastocyst stages. These finding indicate the possible broader application for OPS methods, as frozen-thawed embryos may be accompanied by developmental stage according to requirements of the survival ability after freezing of blastocyst stage in the pig.

• Bulletin of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.31-43
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• 1993

본 연구에서는 힁부재가 없는 AFRAMAX급 신구조 방식의 유조선을 개발하고자 하였다. 설계의 기본 개념은 1) 이중선체구조를 채용하여 해난사고 발생시 기름유출 방지를 피하고, 2) 힁부재가 없는 극히 단순한 선체구조를 채용하여 용접 로봇등을 활용한 자동건조 비율을 높임으로써 건조 생산성을 향상시키는데 주안점을 두고 있다. 설계 결과 얻어진 선체구조는 기존의 유조선 구 조와 매우 상이하다. 초기구조설계단계에서 구조 부재의 치수는 기존의 선급설계 지침을 활용 하여 결정하였으나, 기존의 유조선 구조와 비교하여 구조배치가 크게 바뀌어 졌기 때문에 기존의 선급설계지침을 만족했다고 해서 구성부재와 국부구조뿐만 아니라 구조 전체적으로도 충분한 구조안전성을 가지고 있는지는 확실치 않다. 따라서 직접구조해석에 의한 구조안전성 평가가 필수적으로 요구되며, 이를 위해 저자들은 선체구조의 최종 종강도(ultimate longitudinal strength), 최종 힁강도(ultimate transverse strength) 및 최종 국부강도(ultimate local strength )를 기준으로한 구조안전성 평가를 수행하였다. 본 논문에서는 이들 중에서 국부 구조부재에 대한 안전성평가 문제만을 다루었다. 결론적으로, 본 연구에서 개발한 선체구조는 건전상태(intact condition)하에서 뿐만 아니라 손상상태하에서도 구조부재는 좌굴 또는 붕괴하지 않고 전반적 으로 충분한 구조안전성을 가지고 있다는 결론을 내릴 수 있었다.

• Korean Journal of Construction Engineering and Management
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• v.19 no.6
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• pp.86-93
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• 2018

Infrastructure which mandatory in human life causes large environmental loads when they are being installed and maintained. Especially, maintenance is performed over a long period of time. Also, there is a limit to suggest a reliable estimated value because environmental loads are changed according to methods of maintenance and periods. In this study, we developed a Environmental Load Estimating Model to evaluate value and plan as soon as possible in the Early Design Phases while maintaining a tunnel. To estimate environmental loads by using brief design information, we analyze a calculation methodology of environmental loads in maintenance phases. Furthermore, we apply periods of maintenance work and maintenance factors considered a characteristic of long-term maintenance. Finally, a main purpose is that this program makes all users estimate environmental loads in maintenance phases easily and quickly. Accordingly, it is considered that the Environmental Load Estimating Model offer assistance to eco-friendly maintenance of the road and tunnel construction.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.2 s.48
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• pp.1-10
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• 2006

Reinforced concrete bridge columns with relatively small aspect ratio show flexure-shear behavior, which is flexural behavior at initial and medium displacement stages and shear failure at final stage. Since the columns with flexure-shear failure have lower ductility than those with flexural failure, shear capacity curve models shall be applied as well as flexural capacity curve in order to determine ultimate displacement for seismic design or performance evaluation. In this paper, a modified shear capacity curve model is proposed and compared with the other models such as the CALTRANS model, Aschheim et al.'s model, and Priestley et al.'s model. Four shear capacity curve models are applied to the 4 full scale circular bridge column test results and the accuracy of each model is discussed. It may not be fully adequate to drive a final decision from the application to the limited number of test results, however the proposed model provides the better prediction of failure mode and ultimate displacement than the other models for the selected column test results.

• The KIPS Transactions:PartD
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• v.17D no.2
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• pp.119-128
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• 2010

The application field of OSS is being expanded farther and the existing studies are well established theoretically but not actually widely used. Because so many criteria and complexity of selection methods result in low efficiency and not proper for use. In this master's thesis, to solve these problems I propose a selecting technique for OSS with less criteria, which is more effective and easy to use than before. Based on the existing studies, we identify assessment criteria which common used and redefine 14 evaluation attributes as well as 31 assessment criteria through elimination and grouping. And evaluate the criteria in four steps such as Initial assessment, Functional assessment, Characteristical assessment and Supplemental assessment. To evaluate the adequacy of suggested technique, 29 database management tools for MySQL are selected as candidates, and applied to the technique I proposed. As the result, time and effort for evaluation is reduced sharply and we can use this technique more easily.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.112-112
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• 2020

하천에서 유해화학물질 유입 사고 발생 시 수환경 피해를 최소화하기 위해 신속한 초기 대응이 필요하다. 따라서, 본 연구에서는 수환경 화학사고 대응 시스템 구축을 위해 하천 실시간 모니터링 지점에서 관측된 유해화학물질의 농도 자료를 이용하여 발생원의 유입 지점과 유입량을 역추적하는 프레임워크를 개발하였다. 본 연구에서 제시하는 프레임워크는 첫 번째로 하천 저장대 모형(Transient Storage Zone Model; TSM)과 HEC-RAS 모형을 이용하여 다양한 유량의 수리 조건에서 화학사고 시나리오를 생성하는 단계, 두번째로 생성된 시나리오의 유입 지점과 유입량에 대한 시간-농도 곡선 (BreakThrough Curve; BTC)을 21개의 곡선특징 (BTC feature)으로 추출하는 단계, 최종적으로 재귀적 특징 선택법(Recursive Feature Elimination; RFE)을 이용하여 의사결정나무 모형, 랜덤포레스트 모형, Xgboost 모형, 선형 서포트 벡터 머신, 커널 서포트 벡터 머신 그리고 Ridge 모형에 대한 모형별 주요 특징을 학습하고 성능을 비교하여 각각 유입 위치와 유입 질량 예측에 대한 최적 모형 및 특징 조합을 제시하는 단계로 구축하였다. 또한, 현장 적용성 제고를 위해 시간-농도 곡선을 2가지 경우 (Whole BTC와 Fractured BTC)로 가정하여 기계학습 모형을 학습시켜 모의결과를 비교하였다. 제시된 프레임워크의 검증을 위해서 낙동강 지류인 감천에 적용하여 모형을 구축하고 시나리오 자료 기반 검증과 Rhodamine WT를 이용한 추적자 실험자료를 이용한 검증을 수행하였다. 기계학습 모형들의 비교 검증 결과, 각 모형은 가중항 기반과 불순도 감소량 기반 특징 중요도 산출 방식에 따라 주요 특징이 상이하게 산출되었으며, 전체 시간-농도 곡선 (WBTC)과 부분 시간-농도 곡선 (FBTC)별 최적 모형도 다르게 산출되었다. 유입 위치 정확도 및 유입 질량 예측에 대한 R²는 대부분의 모형이 90% 이상의 우수한 결과를 나타냈다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.2
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• pp.178-189
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• 1994

Fine $BaTiO_3$ powder was synthesized from the various starting solution with 0.05 M by ultrasonic spray pyrolysis method. The conditions of synthesis were fixed on flow rate was 0.5 cm/sec, low temperature furnace was $300^{\circ}C$, and high temperatures furnace was $700^{\circ}C$. The formation procedure was investigated directly by SEM with the collected particle from the each reaction step. Also, the trace of particle in reaction tube was researched theoretically. Fine $BaTiO_3$ was synthesized only in the case of nitrate aqueous solution. The synthesized $BaTiO_3$ powder was porous and spherical which was consist of primary particle at the size of 19.1 nm. The formation procedure was as follows : the particle size decreased in drying step and then increased in initial thermal decomposition step. Finally, particle size was decreased to $0.42 {mu}m$. The trace of particle in reaction tube was also theoretically simulated and discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.729-740
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• 1994

In the shape optimal design based on h-version of FEM, the ideal mesh for the initial geometry most probably will not be suitable for the final analysis. Thus, it is necessary to remesh the geometry of the model at each stage of optimization. However, the p-version of FEM appears to be a very attractive alternative for use in shape optimization. The main advantages are as follows; firstly, the elements are not sensitive to distortion for interpolation polynomials of order $p{\geq}3$; secondly, even singular problems can be solved more efficiently with p-version than with the h-version by proper mesh design; thirdly, the initial mesh design are identical. The 2-D p-version model for shape optimization is presented on the basis of Bezier's curve fitting, gradient projection method, and integrals of Legendre polynomials. The numerical results are performed by p-version software RASNA.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.157-164
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• 2007

Launch Interface Ring roles as connection department of satellite and launcher for to deliver all structure loads that occur from the satellite, and one of the most intensive load received parts. Especially COMS, the first Korean developing GEO satellite, needs Launch Interface Ring with Tank Support Beam because of dissymmetry fuel tanks. The purpose of this study is the suitable form decision of Launch Interface Ring at preliminary design of COMS. In this study, launch mass and design constraints are investigated. Moreover, optimization algorithm and simplification technique are used. At the beginning of this study, three types of launch interface ring were presented and finally model 3 was the lightest design for resistance of launch environment. Nevertheless, model 1 can be suggested for application to COMS because of the satellite gravity center control and ease of fabrication.

• Korean Journal of Construction Engineering and Management
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• v.5 no.2 s.18
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• pp.115-122
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• 2004

This study identifies various risk factors associated with activities of early construction stage, then establishes the Risk Breakdown Structure(RBS) by classifying the risks into the three groups; Common risks, risks for Earth works, and risks for Foundation works. The Common risks are identified and classified by considering various aspects of the early construction stage such as financial, political, constructional aspects, etc. The risks for Earth works and Foundation works are identified in detail by surveying technical specifications, relevant claim cases and interviewing with experts. These risks are classified based on the Wok Breakdown Structure(WBS) of the early construction stage. The WBS presented in this study classifies the works of early construction stage into four categories; excavation, sheeting works, foundation works, footing works. This study suggests a risk analysis method using fuzzy theory for construction projects. Construction risks are generally evaluated as vague linguistic value by subjective decision making. Fuzzy theory is a proper method to quantify vague conditions of construction activities. Therefore, this study utilizes fuzzy theory to analyse construction risks. The weight of risks is estimated by reflecting the interrelationship among risk factors from absolute weights obtained by fuzzy measure into the relative weights by Analytical Hierarchy Process(AHP). The interrelationship is estimated by Sugeno-fuzzy measure.