• 한국가축번식학회지
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• 제19권4호
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• pp.293-305
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• 1996

Retrovirus는 DNA가 아닌 RNA를 유전 물질로 갖고 있는 동물 virus인데 각 virus는 RNA와 함께 크게 gag, pol. 그리고 env 등의 3가지 단백질로 구성되어 있다. gag 단백질은 virus의 내부구조를 형성하는 단백질이고, pol단백질은 감염을 통해 표적 세포에 도입된 retrovirus의 RNA를 DNA로 역전사시키는 reverse transcriptase의 역할을 하며, env단백질은 virusdml 외부를 구성하는 단백질로써 이 단백질에 의해 각 retrovirus의 종류에 따른 감염이 가능한 표적세포의 종류가 결정된다(host cell specificity). 따라서 어떤 retrovirus의 envelope단백질과 표식세포에 있는 retrovirus의 envelope 단백질에 대한 특정 receptor와의 상호 작용에 의해 세포속으로 도입된 virus의 RNA는 reverse transcriptase에 의해 DNA로 역전사된 후 표적세포의 genomic DNA에 삽입되는 특징을 가진다. 이러한 특징을 가진 retrovirus vector system은 형질 전환 동물의 생산에 있어서 현재까지의 주된 방법인 수정란의 pronucleus에의 DNA microinjection방법 보다 여러 가지 면에서 우수함에도 불구하고 쥐 이외의 다른 동물에서는 거의 이용되고 있지 않는 실정이다. 주된 원인으로는 현재 사용되고 있는 대부분의 retrovirus vector system이 쥐의 백혈병 virus를 근간으로 하기 때문에 이 system에서 생산된 virus는 쥐 이외의 다른 동물, 특히 유제류의 세포에는감염성이 아주 약하기 때문이다. 이러한 결점을 해결하기 위하여 최근에 기존의 쥐 백혈병 virus의 envelope protein을 vesicular stomatitis virus의 G protein으로 대체한 hybrid retrovirus vector system이 개발되었다. 이러한 system에서 생산되는 virus는 조류를 포함한 거의 모든 종류의 동물세포를 감염시킬 수 있으며 몇몇 특정세포에 대해서는 기존의 retrovirus vector system에 비해 1,000배 이상의 높은 감염도를 나타내는데 그 특징이 있다. 따라서 이러한 새로운 virus vector system을 이용할 경우, 보다 다양한 종에 있어서 형질전환 동물을 효율적으로 생산할 수 있을 뿐만 아니라 형질전환 동물의 생산 방법 자체를 다양화 시킬 수 있다고 본다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.191-198
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• 2005

Slope failures during heavy rainfall have resulted in death of life and economic loss. In recent years, the research on slope damage assessment using Geographical Information System(GIS) has been actively carried out by researchers of several goverment organizations and schools. The researchers in Highway and Transportation Technology Institute (HTTI) of Korea Highway Corporation has developed the GIS database(DB), including highway, rainfalls, soil or rock geometry, types of damage, etc. and have been working on the damage assessment of highway slopes. The DB has been established and summarized in two different ways, such as highway routes and administrative districts. Grid of rainfall intensity generated by maximum rainfalls of each administrative district has been devloped. It shows good correlation of slope damage with heavy rainfalls. Most of damaged slopes were found in the amount of 100 mm to 300 mm rainfalls.

• International Journal of Concrete Structures and Materials
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• 제2권2호
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• pp.91-98
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• 2008

Curved bridges are important components of a highway transportation network for connecting local roads and highways, but very few data have been collected in terms of their field performance. This paper presents two-years monitoring and system identification results of a curved concrete box-girder bridge, the West St. On-Ramp, under ambient traffic excitations. The authors permanently installed accelerometers on the bridge from the beginning of the bridge life. From the ambient vibration data sets collected over the two years, the element stiffness correction factors for the columns, the girder, and boundary springs were identified using the back-propagation neural network. The results showed that the element stiffness values were nearly 10% different from the initial design values. It was also observed that the traffic conditions heavily influence the dynamic characteristics of this curved bridge. Furthermore, a probability distribution model of the element stiffness was established for long-term monitoring and analysis of the bridge stiffness change.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.225-229
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• 2001

There are about 41% (by weight) of scrap tires were pulverized to produce rubber powder and granules in the tire recycling industry of Taiwan. However, the reuse of the by-products, steel and fiber, of the scrap tires still needs to be improved. It is difficult to remove the remaining rubber on the surface of steel or fiber. This problem reduce the availability for further reuse of steel and fiber. In addition to the improvement of magnetic, gravity separation techniques or carbonization process, using cryogenic shredding process to separate rubber and fiber (or steel) had been used as another alternative. Cryogenic shredding process for scrap tires showed many advantages, the objective of this paper is to explore the mechanisms for the cryogenic shredding process of scrap tires. Cryo-SEM is used to investigate the topographic information, in-situ, from room temperature to -195$^{\circ}C$ . One square inch shredded tire chips are prepared for SEM study. The percentage of the shrinkage of rubber is also estimated, ca. 6.7%. Mechanisms of cryogenic shredding effects on the tire chips are discussed. The proper practice of cryogenic shredding process far scrap tires is also suggested.

• 한국해안·해양공학회논문집
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• 제31권6호
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• pp.344-350
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• 2019

본 연구에서는 3차원 유동해석 수치모형인 OpenFOAM의 waves2Foam을 사용하여 무공케이슨 방파제의 전면이 피복되지 않은 조건과 테트라포드(TTP)로 피복된 조건에서 직립 케이슨에 작용하는 파압을 수치모의하고 수리실험 결과와 비교하였다. 파압 수치모의 결과는 수리실험 결과와 상당히 잘 일치하였다. 이를 통해 테트라포드로 피복된 영역을 다공성 매체로 구현할 수 있는 경험식의 최적 파라미터 조합을 제시하였다.

• 한국물환경학회지
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• 제21권6호
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• pp.630-636
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• 2005

Groundwater contamination by nitrate exceeding water quality criteria (10 mg $NO_3{^-}-N/L$) occurs frequently. Fumarate, acetate, formate, lactate, propionate, ethanol, methane and hydrogen gas were evaluated for their nitrate removal efficiencies and removal rates for in situ bioremediation of nitrate contaminated groundwater. Denitrification rate for each substrate was in the order of: fumarate > hydrogen > formate/lactate > ethanol > propionate > methanol > acetate. Microcosm studies were performed with fumarate and acetate. When fumarate was used as a substrate, nitrate was removed 100 percent with rate of 0.66 mmol/day while conversion rate from nitrate to nitrogen gas or another by-product was 87 percent. 42 mg of fumarate was needed to remove 30 mg $NO_3{^-}-N/L$. When using acetate as carbon source, 31 percent of nitrate was removed during initial adjustment period. Among removed fraction, however, 83 percent of nitrate removed by cell growth. Overall nitrate removal rate was 0.37 mmol/day. Acetate showed longer lag time in consumption compared to that of nitrate, which implying that acetate would be better carbon source compared to fumarate as more amount was utilized for nitrate removal than cell growth.

• 한국구조물진단유지관리공학회 논문집
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• 제7권2호
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• pp.219-229
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• 2003

The objective of this work is to verify the Code specified girder distribution factors for short and medium span bridges. To accomplish this objective, field tests were carried out on seventeen simply supported highway bridges. This paper presents the procedure and results of field tests that were performed to verify girder distribution factors. Finite Element analyses previously performed at the University of Michigan indicated that in most cases currently used girder distribution factors specified in AASHTO Codes are too conservative. However, these studies also showed that for short spans and short girder spacings, the girder distribution factors can be too permissive. Therefore, this paper focused on experimental evaluation of girder distribution factors for short and medium span steel girder bridges. The results were compared with the distribution factors specified by AASHTO Standard (2000) and AASHTO LRFD Code (1998). It has been found that the measured girder distribution factors are lower than AASHTO values in most cases, and sometimes the code specified values are overly conservative. The research work involved formulation of the testing procedure, selection of structure, installation of equipment, measurements, and interpretation of the results.

• 한국지반신소재학회논문집
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• 제6권2호
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• pp.27-32
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• 2007

본 연구에서는 절토사면 공법선정시 고려해야 할 영향인자에 대한 가중치 결정과 사면보강공법 선호도를 AHP기법을 이용하여 분석하였다. 연구, 설계, 시공업에 종사하고 있는 전문가를 대상으로 분석한 결과 공법선택시 안정성 및 내구성, 환경성이 가장 중요한 영향인자로 조사되었으며, 안전율 증가법 위주로 분석된 사면보강공법 선호도 조사에서는 경제성과 유지관리 용이성, 안정성에서 가장 우수한 평가를 받은 옹벽공법과 절토공법이 가장 선호도가 높은 공법으로 분석되었다.

• 생명과학회지
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• 제11권5호
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• pp.400-404
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• 2001

최근 새로운 인간 내생 레트로바이러스 패밀리(HERAV-S)가 인간의 X 염색체상에서 동정 되었다. 그 길이는 6.7kb 이며 LTR-gag-pol-env-LTR의 일반적인 레트로바이러스의 구조를 가졌다. PCR 방법과 염기서열분석을 통하여 인간 게놈 DNA에서 HERV-S LTR 패밀리를 동정하였다. 네 개의 LTR엘리먼트(HSL-1, HSL-5, HSL-10, HSL-11)가 동정 되었으며, 이들은 HERV-S LLR 패밀리는 영장류의 진화과정에서 진화적인 분기를 통해 주된 2개의 그룹으로 나뉘어졌다. 영장류에서 이러한 HERV-S LTR들의 연구가 이루어진다면 이들의 영장류 게놈 내의 삽입시기를 알 수 있고 또한 인류의 진화를 이해하는데 크게 이바지 할 것이다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.17-22
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• 2009

Reliability analyses were performed to quantify the risk in axially loaded large-scale pile foundations in consideration of pile-soil interaction and uncertainties on various design variables. The finite difference method based on an equivalent soil spring model and a load transfer method and Monte Carlo simulation method are integrated in the framework of reliabilty analysis. The applicability and efficiency of the proposed method in the safety assessment of axially loaded pile-soil system was verified using a realistic example. Since the proposed method can explicitly consider uncertainties in various design variables, and quantify failure probability of a pile foundation, it can be used to estimate risk, to obtain basic informations for life cycle cost analysis, and to develop code requirements for a reliability-based design of pile foundations.