• Steel and Composite Structures
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• 제26권2호
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• pp.227-239
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• 2018

Integral abutment bridges (IABs) have no joint across the length of bridge and are therefore also known as jointless bridges. IABs have many advantages, such as structural integrity, efficiency, and stability. More importantly, IABs have proven to be have both low maintenance and construction costs. However, due to the restraints at both ends of the girder due to the absence of a gap (joint), special design considerations are required. For example, while replacing the deck slabs to extend the service life of the IAB, the buckling strength of the steel girder without a deck slab could be much smaller than the case with deck slab in place. With no deck slab, the addition of thermal expansion in the steel girders generates passive earth pressure from the abutment and if the applied axial force is greater than the buckling strength of the steel girders, buckling failure can occur. In this study, numerical simulations were performed to estimate the buckling strength of typical steel girders in IABs. The effects of girder length, the width of flange and thickness of flange, imperfection due to fabrication and construction errors on the buckling strengths of multiple and single girders in IABs are studied. The effect of girder spacing, span length ratio (for a three span girder) and self-weight effects on the buckling strength are also studied. For estimation of the reaction force of the abutment generated by the passive earth pressure of the soil, BA 42/96 (2003), PennDOT DM4 (2015) and the LTI proposed equations (2009) were used and the results obtained are compared with the buckling strength of the steel girders. Using the selected design equations and the results obtained from the numerical analysis, equations for preventing the buckling failure of steel girders during deck replacement for maintenance are presented.

• 한국초지조사료학회지
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• 제40권3호
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• pp.177-181
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• 2020

Data on the crude protein requirements of elk doe are nonexistent and the data are essential for their management in Korea. Therefore, this study was conducted to evaluate the crude protein requirement for maintenance of elk doe. Three female elk deer were used in 3 × 3 Latin square design with three diets containing three levels of crude protein (CP) that contained low crude protein (approximately 12%), medium crude protein (15%), and high crude protein (18%). Each three elk doe trials included a 14-day preliminary period and a 5-day collection period. Crude protein intake was 4.83, 6.26, and 9.00 g/d for 12%, 15%, and 18% of CP level, respectively. Crude protein balances were 1.04, 1.41, and 4.14 for 12%, 15%, and 18% of CP level, respectively. The maintenance requirement for CP from the regression equation between CP intake and CP balance were 3.70 g/BW^0.75.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6932-6942
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• 2014

고속도로는 국가발전의 원동력인 사회기반시설물 중의 하나로 사회발전에 중요한 역할을 담당하고 있으며 고속도로 연장도 계속적으로 증가되고 있으며, 수송의 고속성 뿐만 아니라 안전성, 저공해성, 쾌적성 등 한층 높은 수준의 서비스가 요구되고 있다. 그러나 한정된 고속도로 유지보수 예산으로 보수가 지연되어 포장상태는 계속적으로 악화되고 있는 실정이다. 따라서 본 연구에서는 기존 문헌 및 포장유지보수프로세스 문제점 고찰을 통하여 최적의 고속도로 포장유지보수 관리 체계를 확립하고 개선된 고속도로 포장유지보수 업무 프로세스를 제시하여. 한정된 예산 내에서 최소 비용으로 최대 서비스 제공이 가능한 장수명 포장관리 체계의 확립과 포장의 내구수명을 연장 할 수 있는 현실적으로 실무에 적용이 가능한 효율적인 고속도로 포장유지관리가 가능토록 하고자 한다. 본 연구에서 제시한 개선된 유지보수프로세스를 검증한 결과, 기존 방법보다 공사일수 감소, 공사비 및 유지관리비 절감의 효과가 있었다.

• 한국주거학회논문집
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• 제13권1호
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• pp.44-52
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• 2002

As a result of the expansion of the nuclear family in society, there has been an increase in the number of elderly people who want to live independently of their children. Australia is one of the countries which has initiated an extensive welfare program for its senior citizens. These services include maintenance of, and alterations to their own homes to make living conditions safer and more manageable. This case study was aimed at finding ways of adapting the services provided in Australia, to meet the needs of elderly Koreans who are in similar situations. It evaluated houses which had been renovated and altered fur the normal as well as the disabled elderly in both Melbourne and Sydney. results of research were as following : 1) Most elderly usually wished to remain as long as possible in their own home and it made them very stable in psychologically. 2) Housing maintenance and alterations were provided as one of social care services fur elderly with low expense and loan from government. 3) Many elderly were also getting various kinds of social services, fur example, meals on wheels, transportation and cleaning service with housing alterations and these ones let their quality of life more improved. 4) Occupational therapist and Architect were always involved in the process of housing alterations for disabled elderly. 5) The alterations which related to bathroom, toilet and steps were very popular and those were considered essential design guide applications for planning of housing for elderly in the future.

• 한국미생물·생명공학회지
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• 제17권3호
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• pp.173-177
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• 1989

HeLa 세포주의 연속 배양시 세포수가 배지의 이동속도가 증가함에 따라 감소하는 현상을 나타냈으며, 최대 세포수를 유지할 때의 dilution rate은 0.012(1/h)로 wash-out인 0.050(1/h)보다 극히 낮으며, dilution rate이 0.030(1/h)일 때 2.0(mL of cells/L/h)의 최대 세포 생산속도를 보였다. 또한 낮은 배지 이동속도에서 세포수의 감소에 따른 maintenance term의 존재를 확인했다. 더불어 packed cell volume파 산소소비속도의 측정값이 실제 세포증식과 밀접한 관계가 있음이 입증되어 간접방법에 의한 생육도치 측정이 가능하게 되었다. 또한 산소 yield model에 의해 최대 산소 수율, $Y_{O2}^{max}$과 maintenance 산소소비속도, m$_{O2}$가 각각 4.1$\times$$10^5$(cells/mmole $O_2$)와 10.71$\times$$10^{-9}$(mmole $O_2$/ cells/h)로 측정되었다.

• 대한기계학회논문집A
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• 제37권10호
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• pp.1291-1296
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• 2013

위험도 평가 기술은 주로 플랜트의 많은 운영설비 중 대형사고나 피해를 유발할 수 있는 위험설비를 선별하는 목적으로 개발되었다. 설비의 위험도를 평가하여 위험도의 크기에 따라 순위를 정하고 이 순위를 기준으로 정비자원을 투입하는 순서나 정비작업의 시급성을 판단한다. 위험도란 고장이 발생할 확률과 고장이 발생할 경우에 수반되는 파손피해의 곱으로 정의된다. 위험도 평가방법으로는 간단한 손상 및 고장 평가기법을 이용하여 기본적인 고장확률 데이터를 확보하고 정성적인 문진을 통해 이를 보완하는 준 정량적 방법이 많이 사용되고 있다. 본 논문에서는 준 정략적 평가를 이용하여 석탄화력발전소의 보일러설비에 대한 위험도 평가를 수행하고 이를 기반으로 설비 별차기 정비주기를 선정하였다.

• 한국농공학회지
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• 제35권1호
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• pp.67-75
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• 1993

This study is to analyze both root growth and soil moisture extraction pattern during the growing period of upland crops with respect to soybean, redpepper, sesame. Field and lysimeter tests were conducted under 12 treatments of soil moisture level by the San Cristobal experimental design(1981) and 3 soil type(sand, sandy loam, silty loam) for 4 years('87-'90) at the experimental plot of Rural Development Administration located in Suwon. The results of this study are summarized as follows : 1.For soybean, redpepper and sesame, root growth in dry soil was better than that in wet soil and it could be expressed as a sin function in terms of time. Maximum root depth was about 55cm, 44cm, 40cm respectively. 2.The average soil moisture extraction pattern for soybean, redpepper and sesame were 61.4%, 62.8%, 79.5% for zone l(0-l5cm). 25.5%, 27.1%, 18.3%, for zone 2(15-30cm).11.4%, 9.8%, 2.3% for zone 3(30-45cm), 1.7%, 0.3%, 0.04% for zone 4(45-60cm) respectively. This means that Zone 1 would be the dominant zone in irrigation scheduling. 3.With respect to soybean, the soil moisture extraction pattern(SMEP) was varied somewhat according to the erent maintenance of soil moisture level. The average SMEP for high maintenance of soil moisture was 46%, 29%, 17%, 8%, for middle maintenance of soil moisture was 43%, 29%, 17%, 11 % and for low maintenance of soil moisture was 40%, 28%, 20%, 12%, respectively. 4.With respect to soybean, the soil moisture in the upper layer was distinctly consumed more than that in the lower layer for clay loam soil and the soil moisture of all layers was consumed evenly for sand soil. The SMEP for sandy loam soil showed a middle result compared with the above 2 soil types.

• 한국구조물진단유지관리공학회 논문집
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• 제15권5호
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• pp.160-168
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• 2011

성수대교 삼풍백화점 붕괴사고 등을 계기로 유지관리 분야의 중요성이 대두되면서 1995년 시설물의안전관리에관한특별법이 제정되어 점검 진단이 실시되는 등 본격적인 유지관리체제가 시작됐다. 그러나 점검 진단의 역사가 일천한 관계로 점검 진단에 대한 기술수준이 낮았고 연구 성과 또한 미흡하여 부실 점검 진단에 대한 우려가 상존해 있었다. 이에 2002년 평가제도가 도입되면서 부실 점검 진단 비율이 지속적으로 낮아져 왔다. 그러나 최근 점검 진단 실시결과 평가실적에 따르면 향후 부실 점검 진단비율이 더 이상 낮아지기 힘든 경향을 보이고 있다. 이를 계기로 부실 점검 진단과 관련하여 관련기관의 설문조사와 메커니즘 측면에서 고찰하므로서, 부실 점검 진단이 초래되는 근원적인 문제점을 나열하였고, 이를 바탕으로 현행 평가제도의 개선방향을 제시 하고자 하였다.

• 한국가스학회지
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• 제17권4호
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• pp.39-44
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• 2013

최근 화학공장에서는 대형 폭발사고 등이 주로 유지 보수의 정비 시에 많이 발생되고 있다. 정비 시에 효과적인 재해예방을 하기 위해서는 핵심대상을 찾는 것이 매우 필요하다. 이 논문에서는 재해예방의 핵심요인을 찾기 위해 핵심대상으로 화학설비를 선정하였고, 화학설비별로 위험순위도를 정하여 재해예방의 대책을 세우는 우선순위를 밝히고자 하였다. 연구방법으로 화학설비의 종류는 재해분석을 통하여 찾고, 화학설비별 위험도는 재해분석을 통해 가능성인 재해빈도와 중대성인 재해강도의 근로손실일 수를 기준하여 산정하였다. 또한 화학설비별로 전문가들의 지식과 경험을 바탕으로 한 지식기반 기법에 의한 가능성과 중대성 자료를 활용하여 위험도를 산정하였다. 연구결과, 화학공장의 정비 시에 재해예방을 위해 화학설비별 위험순위는 반응기, 건조기, 탱크로리 등의 순위로 나타났다. 이 결과로부터 화학공장의 정비 시에 재해예방을 위해 위험순위에 따른 각별한 대책과 주의를 기울여야 할 것으로 사료된다.

• Tuberculosis and Respiratory Diseases
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• 제85권3호
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• pp.227-236
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• 2022

Background: The use of low-dose inhaled corticosteroid-formoterol as reliever monotherapy has recently been recommended in the asthma treatment guidelines. However, the efficacy of this treatment strategy has not yet been determined during the stepping-down period in moderate asthma. This study aimed to evaluate the feasibility of reducing treatment to as-needed budesonide-formoterol (BFM) in moderate asthma with complete remission. Methods: We randomly assigned 31 patients (8 males and 23 females with a mean age of 57.2 years) with complete remission of asthma by inhaled BFM (160/4.5 ㎍) twice daily to receive BFM (160/4.5 ㎍) as needed (16 patients), or budesonide (BUD) (200 ㎍) twice daily (15 patients). The study was an open-label study done for 48 weeks, with the primary outcome as the cumulative percentages of patients with treatment failure (asthma exacerbation or loss of asthma control or lack of satisfaction after using medications) in the two groups. Results: Six patients (42%) using as-needed BFM had treatment failure, as compared with three patients (21.4%) using BUD maintenance (hazards ratio for as-needed BFM, 1.77; 95% confidential interval, 0.44-7.12; p=0.41). The changes in forced expiratory volume in 1 second were -211.3 mL with as-needed BFM versus -97.8 mL with BUD maintenance (difference, 113.5 mL; p=0.75) and the change in fractional exhaled nitric oxide was significantly higher in both groups, at 8.68 parts per billion (ppb) in the as-needed BFM group and 2.5 ppb. in the BUD maintenance group (difference, 6.18 ppb; p=0.049). Conclusion: Compared with BUD maintenance, there were no significant differences in treatment failure rate in patients who received as-needed BFM during the stepping down period in moderate asthma. However, they showed reduced lung function and relapsed airway inflammation. The results are limited by imprecision, and further large RCTs are needed.