교량의 신뢰성 검증을 위한 지역적 활하중 확률모형 구축

엄준식(Jun Sik Eom) 한국신뢰성학회 2016 신뢰성응용연구 Vol.16 No.2

Purpose: Majority of bridges and roads in Gangwon Province have been carrying loads associated with heavy materials such as rocks, mining products, and cement. This location-specific live loads have contributed to the present situation of overloading, compared to other provinces in Korea. However, the bridges in Gangwon province are designed by national bridge design specification, without considering the location-specific live load characteristics. Therefore, this study focuses on the real traffic data accumulated on regional weighing station to verify the live load characteristics, including actual live load gross vehicle weight, axle weight axle spacings, and number of trucks. Methods: In order to take into account the location specific live load, a governmental weigh station (38th national highway Miro) have been selected and the passing truck data are processed. Based on the truck survey, trucks are categorized into 3 different shapes, and each shape has been idealized into normal distribution. Then, the resulting survey data are processed to predict the target maximum live load values, including the axle loads and gross vehicle weights in 75 years service life span. Results: The results are compared to the nationally used DB-24 live loads, and the results show that nationally recognized DB-24 live load does not sufficiently represent real traffic in mountaineous region in Gangwon province. Conclusion: The comparison results in the recommendation of location-specific live load that should be taken into account for bridge design and evaluation.

양성자 핵자기공명분광기를 이용한 고온스트레스에 따른 Holstein 수소의 반추위액과 혈액 내 대사체 프로파일링 연구

엄준식(Jun Sik Eom),이신자(Shin Ja Lee),이상석(Sang Suk Lee),서성원(Seongwon Seo),박성민(Seong Min Park),이성실(Sung Sill Lee) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.1

Shared nothing 구조하에서 Chunk - based Caching 전략에 의한 OLAP Query response time의 속도향상.

엄준식(Jun Sik Eom),정병수(Byung Soo Jeong) 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.2Ⅰ

현재 의사결정 시스템을 위한 데이터 웨어하우스는 데이터베이스 분야에서 비약적인 발전을 해오고 있다. 이 분야에서 중요한 사항은 사용자의 질의에 대한 응답시간이다. 사용자로부터 질의가 요구되면 과거의 많은 데이터를 분석하여 적절한 시간 내에 분석결과를 되돌려 줄 수 있어야 하는데 데이터 웨어하우스의 특성상 대용량의 데이터를 저장하고 분석 시에 많은 데이터를 검색해야 하므로 질의 응답시간에 많은 시간이 소요된다. 이 논문에서는 Chunk based caching기법에 의해서 새로이 요구되는 질의에 대해 이미 메모리에 캐시 되어진 내용을 이용하는 방식을 통해 디스크의 I/O 횟수를 줄임으로써 질의 응답시간을 단축시키는 기법을 소개한다. 또한 chunk miss에 대한 처리를 병렬로 수행함으로써 메모리에 캐시되지 않은 내용을 디스크로부터 로드하는 시간을 단축시키는 방법도 아울러 소개한다.

단.중경간 강형교 거더의 횡분배 모델

엄준식 ( Eom Jun-sik ),( Andrzej S. Nowak ),노병철 ( Lho Byeong-cheol ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 논문집 Vol.7 No.2

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.

Resistance Model for Reliability Analysis of Existing Steel Girder Bridges

Jun Sik Eom(엄준식) 한국신뢰성학회 2013 신뢰성응용연구 Vol.13 No.4

Because of financial and safety concerns, there are needs for more accurate prediction of bridge behavior. Underestimation of the bridge load carrying capacity can have serious economic consequences, as deficient bridges must be repaired or rehabilitated. Therefore, the knowledge of the actual bridge behavior under live load may lead to a more realistic calculation of the load carrying capacity and eventually this may allow for more bridges to remain in service with or without minor repairs. The presented research is focused on the reliability evaluation of the actual load carrying capacity of existing bridges based on the field testing. Seventeen existing bridges were tested under truck load to confirm their adequacy of reliability. The actual response of existing bridge structures under live load is measured. Reliability analysis is performed on the selected representative bridges designed in accordance with AASHTO codes for bridge component (girder). Bridges are first evaluated based on the code specified values and design resistance. However, after the field testing program, it is possible to apply the experimental results into the bridge reliability evaluation procedures. Therefore, the actual response of bridge structures, including unintentional composite action, partial fixity of supports, and contribution of nonstructural members are considered in the bridge reliability evaluation. The girder distribution factors obtained from the tests are also applied in the reliability calculation. The results indicate that the reliability indices of selected bridges can be significantly increased by reducing uncertainties without sacrificing the safety of structures, by including the result of field measurement data into calculation.

사료 급여 방식에 따른 반추위액 내 휘발성지방산과 단당류 비교 분석과 대사산물 분석

엄준식(Jun-Sik Eom),이신자(Shin-Ja Lee),이유경(Yoo-Gyung Lee),이성실(Sung-Sill Lee) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.12

거세한우 3두를 3x3 Latin square design 시험방법에 적용하여 사료 적응 기간 10일 후 사료 급여 방식에 따른 반추위액 내 휘발성지방산과 단당류 비교 분석 및 대사산물 분석에 대한 연구를 수행하였다. 연구 결과 HPLC와 HPAEC에서 측정되지 않은 휘발성지방산과 단당류들은 1H-NMR에서는 측정이 가능 한 것을 알 수 있었다. 1H-NMR에서 측정된 대사산물중, carbohydrate 계열 대사산물 pyruvate는 사료 급여 전 반추위액에서만 측정 되었으며, succinate는 사료 급여 전·후 에서 모두 측정 되었다. Amino acid 계열 대사산물은 총 9가지가 측정 되었다. Lipid 계열 대사산물 ethylene glycol는 사료 급여 전 Con구에서 유의적(P<0.05)으로 높게 측정 되었다. Aiphatic acylic compounds 계열 대사산물 trimethylamine N-oxide는 유의적인 차이는 보이지 않았다. 이번 연구를 통해 <SUP>1</SUP>H-NMR를 이용하여 반추위액 내 많은 대사산물 측정이 가능한 것을 알 수 있었으며 사료 급여 전·후 급여 방식에 따라 대사산물의 변화가 나타나는 것을 확인 할 수 있었다. This study was conducted to investigate VFA, monosaccharides and metabolites in rumen fluid according to feeding methods. Three castrated Hanwoo steers were used to the 3x3 Latin square design, 10 day for the diet adaptation period. VFA and monosaccharides which were not detected by HPLC and HPAEC however, those were detected by 1H-NMR. Among the metabolites measured by 1H-NMR carbohydrate metabolites, pyruvate was detected only in the rumen fluid before feeding and succinate was detected before and after feeding rumen fluid. In amino acid total 9 metabolites were detected. In lipid metabolites, ethylene glycol was significantly higher (P<0.05) in before feeding Con group. In aliphatic acylic metabolite, trimethylamine N-oxide was no significant difference observed compare to Con group. In this study, many metabolites were observed in the rumen fluid by 1H-NMR, and it confirmed that rumen metabolic products were changed by feeding methods.

기지하중을 받는 교량구조물의 현장 계측 및 해석에 따른 응력분포 연구

엄준식 ( Eom Jun-sik ),노병철 ( Lho Byeong-cheol ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 논문집 Vol.7 No.3

본 연구는 기지하중을 이용하여 교량의 효율적 평가를 하기 위한 것이다. 계산상 내하력이 부족한 것으로 평가된 교량의 하중저항능력은 기존의 방법에 의한 평가능력을 상회하는 경우가 일반적이다. 기지하중을 이용한 실험은 미지의 저항능력을 평가할 수 있으며, 따라서 대상교량의 하중저항능력을 정확히 검증할 수 있다. 실험을 위한 기지하중은 일반적인 통행하중보다 큰 것을 사용하여야 한다. 따라서 본 연구에서는 미시간 주에서는 법적으로 허용된 11축 트럭 하중(685kN)을 고려하여, 두 대의 군용탱크와 두 대의 11축 트럭을 이용하였으며, 실험의 안전을 위하여 재하하중의 크기를 점진적으로 증가하면서 계측을 실시하였다. 실험에 의한 대상 교량의 응력수준은 계산에 의한 값보다 다소 작게 측정되었으며, 이는 부적절한 재료강도의 예측, 파라펫이나 가드레일과 같은 비구조요소의 기여, 지지조건의 변화 등에 기인한 것으로 분석되었다. The objective of the presented study is to develop an efficient procedure of proof load testing for existing bridges. By analytical methods, some of these bridges are not adequate to carry normal highway traffic. However, the actual load carrying capacity is often much higher than what can be determined by conventional analysis. Proof load testing can reveal the hidden strength reserve and thus verify the adequacy of the tested bridge. Proof load level required for meaningful tests should be sufficiently higher than legal load. In the state of Michigan, the legal 11-axle truck can weigh up to 685 kN. In this study, a combination of two military tanks and two Michigan 11-axle trucks was used. The proof loads were gradually increased to ensure the safety of the test. After each move, measurements were taken. For the considered bridge, stress levels were rather low compared to pre-test analysis results. This is due to incorrect material strength, structural contribution of nonstructural components such as parapets and railings, and partially fixed supports.

서울 서부의 기피시설에서 재탄생된 공공시설들의 특성

엄준식(Eom, Jun-Sik),안대환(An, Dai-Whan) 대한건축학회 2018 대한건축학회논문집 Vol.34 No.11

The aim of this study is to understand the direction of planning for regeneration based on six representative cases of western part of Seoul that were regenerated from the unpleasant facilities since the 20th century. In particular, the similarities and differences were derived by analyzing the characteristics of the history and the location in terms of the 1st establishment and the regeneration in each cases. As a result, looking the tendency to regenerate the unpleasant facility, it can be seen that there is a correlation between the historical and the locational context when establishing and regenerating. Considering the distinct characteristic of the Location and the history of establishment & regeneration, we could classify the characteristics of public facilities as extroverted tendency and intrinsic tendency analysed by a geographic and an architectural, a programmatic aspects. Therefore, when planning the project regenerated from unpleasant facilities, it should be set considering the locational context and the historical context of establishment & regeneration.

한국에서 유휴 산업시설을 활용한 카페의 재생적 특징 연구 - 대형 근대문화유산의 최근 재생사례를 중심으로 -

엄준식(Eom, Jun-Sik) 대한건축학회 2019 대한건축학회논문집 Vol.35 No.7

In South Korea, the cafes utilizing idle industrial facilities have become popular recently. The purpose of this study is to understand the causes of these social phenomena and to examine the spatial characteristics of cafes regenerated from idle industrial facilities. For the study method, this study first looked at the unique spatial characteristics of Korean cafes and the cause of the increase in the number of cafes regenerated in South Korea. And then it looked at five cases where factories and warehouses built during the industrialization period (1900s~1970s) of South Korea were regenerated as cafes after 2015. Finally, this study was examined the regenerative characteristics that could be transformed from idle industrial facilities into cafes by the type analysis such as the background of the times and the strategy of regeneration. The results showed that three spatial characteristics(large single, multi-functional and emotional) preferred in South Korean cafes appeared in cafes regenerated from idle industrial facilities.

반추동물의 메탄감소를 위한 천연식물 추출물에 관한 연구

이신자,엄준식,이수경,이일동,김현상,강한별,이성실,Lee, Shin-Ja,Eom, Jun-Sik,Lee, Su-Kyoung,Lee, Il-Dong,Kim, Hyun-Sang,Kang, Han-Beyol,Lee, Sung-Sil 한국유기농업학회 2017 韓國有機農業學會誌 Vol.25 No.4

6가지 천연 식물 추출물의 첨가가 반추동물의 메탄 감소에 대한 연구를 수행하였다. 반추위액은 cannula가 장착된 한우에서 채취하였으며, 공시축의 사양관리는 timothy와 농후사료 6:4 비율로 급여하였다. 50 ml serum bottle에 timothy 0.3 g, 반추위액 5 ml, McDougall's buffer 10 ml를 각각 넣고 인삼, 도라지, 유카식물, 동백나무, 차나무, 오갈피 추출물을 기질의 5%를 첨가한 뒤 발효시간대별(3, 6, 9, 12, 24, 48, 및 72시간) 7처리 3반복 수행하였다. pH는 6.55~7.41로 반추위 적정 pH 범위에 속하였다. 건물소화율은 첨가구에서 대조구에 비해 유의적(P<0.05)인 차이가 없었다. 총 가스 발생량은 발효 24시간대 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. 이산화탄소 발생량은 발효 9시간대, 메탄 발생량은 6시간대에서 첨가구와 대조구간 유의적(P<0.05)인 차이가 나타나지 않았다. 미생물성장량은 발효 12시간대 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였고, 발효 24시간대 인삼, 유카식물, 차나무, 오갈피 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. Total VFA 농도는 발효 12시간 차나무, 오갈피 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였고, 발효 48시간 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. Acetate 농도는 발효 24시간 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 감소하였고, propionate 농도는 발효 48시간 인삼, 도라지 첨가구에서 대조구에 비해 유의적(P<0.05)으로 증가하였다. 결과적으로 6가지 천연식물 추출물의 첨가는 in vitro 반추위 발효성상에는 이상이 없었으나 메탄 감소의 효과는 나타나지 않았다. 추후 6가지 천연 식물 추출물의 농도를 달리하여 추가적인 시험이 필요할 것으로 사료 된다. This study was conducted to evaluate natural plant extracts for methane gas reduction in ruminants. Rumen fluid was collected from cannulated Hanwoo cow ($450{\pm}30kg$) consuming 400 g/kg concentrate and 600 g/kg timothy. The 15 ml of mixture comparing McDougall's buffer and rumen fluid in the ratio 2 to 1, was dispensed anaerobically into 50 ml serum bottles. Rumen fluid contents were collected and in vitro fermentation prepared control (timothy, 300 mg), ginseng, balloon flower, yucca plant, camellia, tea plant and ogapi extracts were added at the level of 5% against 300 mg of timothy as a substrate (v/w) and incubated for 3, 6, 9, 12, 24, 48, and 72 h. In vitro pH values range 6.55~7.41, this range include rumen titration. The dry matter digestibility was not differ between all treatments and control. Total gas emission was significantly higher (p<0.05) in ginseng and balloon flower treatments on 24 h than in control. Carbon dioxide emission was not differ all treatments on 9 h than in control and significantly higher (p<0.05) yucca plant, camellia and tea plant treatments on 12 h than control. Methane emission was not differ all treatments on 6 h than in control. The rumen microbial growth rate was significantly higher (p<0.05) in ginseng, balloon flower on 12 h and significantly higher (p<0.05) in ginseng, yucca plant, tea plant and ogapi treatments on 24 h than in control. Total VFA was significantly higher (p<0.05) in tea plant and ogapi treatments on 12 h than in control and significantly higher (p<0.05) in ginseng, balloon flower treatments on 48 h than in control. Acetic acid was significantly lower (p<0.05) in ginseng and balloon flower treatments on 24 h than in control. Propionic acid was significantly higher (p<0.05) in ginseng and balloon flower treatments on 48 h than in control. As a results, sixth natural plant extracts had no significant effect dry matter digestibility and negative on rumen fermentation, but not effect methane reduction.