• 한국농공학회지
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• 제33권4호
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• pp.105-120
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• 1991

This study was performed to investigate the minimum safety factor of embankment in consideration of seismic coefficient by the psuedo-static analysis The variables were cohesion, the internal friction angle, angle of slope, height of seepage, height of embankment, depth of replacement The results obtained were compared with those by Fellenius method, simplified Bishop method and Janbu method. The results were summarized as follows: 1.The increasing rate of the minimum safety factor with the increasing of cohesion appeared larger in Fellenius method and Bishop method than in Janbu method. And that with the increasing of the internal friction angle appeared the lowest value in Janbu method. The minimum safety factor was influenced larger on the internal friction angle than on cohesion. 2.The variation of the minimum safety factor with the height of seepage at 0m and 5 m was nearly similar to Fellenius method, Bishop method and Janbu method. On the other hand, it was decreased suddenly at 25 m. 3.The minimum safety factor with the height of embankment was decreased remarkably under 10 m with the increasing of seismic coefficient. But, it was decreased slowly more than 10 m. As the height of embankment was low, the influence of cohesion appeared larger. 4.In heigher case of the depth of replacement, the phenomenon of reduction of the minimum safety factor appeared remarkably with seismic coefficient increased. And in lower case of the depth of replacement, the minimum safety factor was similar in Fellenius method and Bishop mehtod. But it appeared larger in Bishop method and Janbu method than in Fellenius method with the depth of replacement increased. 5.As the cohesion and the internal friction angle were large, the phenomenon of reduction of the minimum safety factor with the increasing of seismic coefficient appeared remarkably. Also, the influence of seismic coefficient in minimum safety factor appeared larger with the soil parameter increased. 6.When the seismic coefficient was considerated, investigation of the structural body on the slope stability appeared profitably in Fellenius method and Janbu method than in Bishop method.

• Asian-Australasian Journal of Animal Sciences
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• 제15권1호
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• pp.11-15
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• 2002

The present investigation was undertaken to study the effects of non-genetic factors and association among replacement and lifetime production traits. The data on 542 Holstein Friesian cows maintained during 1975-98 at State Cattle Breeding Project, Sector III, Hisar, were utilized. The average sex-ratio, abnormal births, mortality, culling and replacement rates on total calf born and total female calf born basis were 51.62, 8.50, 17.52, 31.05, 22.78 and 51.41 per cent, respectively. The study revealed that a minimum of 4 to 5 progenies are required per cow over its lifetime to replace itself. It indicated that each cow should produce a minimum of 2 female calves during its life so as to replace herself before being lost. The least-squares means for productive herd life, longevity and lifetime production were $1439.32{\pm}87.64$ and $2419.18{\pm}8.25$ days and $11317.95{\pm}913.15kg$, respectively. The heritability estimates for all replacement traits were very low indicating that sire selection may bring no desirable change in these traits. Heritability estimates were $0.178{\pm}0.157$, $0.288{\pm}0.184$ and $0.096{\pm}0.195$ for corresponding lifetime production traits. Breeding values and ranking of sires were generated for replacement and lifetime production traits to estimate the rank correlations between these traits. Moderate desirable rank correlations were obtained between replacement rate and lifetime production traits indicating that sires proven on the basis of milk production are also expected to have better replacement rate.

• 한국지반공학회논문집
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• 제29권11호
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• pp.29-47
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• 2013

본 연구에서는 항만구조물 기초지반에 소일-시멘트 파일을 이용한 말뚝식 지반개량을 적용한 90개 단면에 대해 안정검토를 수행하였고, 수치해석을 포함한 모든 항목에서 안정한 단면별 최소치환율을 결정하였으며, 원심모형실험을 통해 수치해석 결과의 신뢰성을 검증하였다. 연구결과, 기초지반이 매우 연약($s_u$ =15kPa이하)한 경우에는 말뚝식 지반개량이 부적합하고, 항만구조물의 말뚝식 지반개량에는 기초지반과 개량체의 강성비(n)가 최대 50~75이하이고 개량체 강도가 2~3MPa인 소일-시멘트 파일공법이 가장 적합하며, 최소치환율 지배인자가 허용수평변위이므로 말뚝식 지반개량을 설계할 때는 반드시 수평변위를 검토해야 하는 것으로 나타났다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.189-190
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• 2023

Environmental pollution problems are occurring in Jeju Island due to negative treatment of basalt waste. Measures for various approaches and utilization measures are needed to solve the problem of waste stones that occur during basalt processing. In this study, the Properties of permeable blocks with basalt were identified and the applicability and functionality as building materials were reviewed. This experiment is basic data for evaluating the functionality of the permeable block by manufacturing permeable blocks using basalt waste stones and analyzing flexural strength and compressive strength. The higher the basalt waste stone replacement rate, the lower the flexural strength and compressive strength, but it was judged that 20% of basalt waste stone replacement rate that satisfies the minimum flexural strength (4.0MPa) stipulated in KS F 4419 was appropriate. In addition, additional permeability coefficient and absorption rate experiments tended to increase as the basalt lung stone replacement rate increased. Therefore, it is judged that the permeable block using basalt waste stone is superior to the existing permeable block.

• 한국시뮬레이션학회논문지
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• 제33권1호
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• pp.27-34
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• 2024

본 연구는 OECD 평균 수준의 소득대체율 대비 실현 소득대체율이 부족할 위험을 최소화하는 자산배분안을 제안하는 데 그 목적이 있다. 이를 위해 본 연구는 소득대체율 부족 위험을 정의하고 이를 최소화하는 최적 자산배분안을 퇴직연금제도 가입기간, 가입자 소득수준, 추가부담금 수준별로 산출하여 제시하였다. 이를 위해 본 연구는 투자의 대상으로 주식과 예금을 고려하였으며 주식의 경우 GBM 모형에 몬테카를로 시뮬레이션을 수행하여 수익률 분포를 생성하였다. 분석결과, 퇴직연금제도 가입 기간이 30년 이하인 경우, 가입자는 적립금의 최소 70~80%를 위험자산에 투자해야 소득대체율 부족 위험을 최소화할 수 있는 것으로 나타났다. 다만, 가입자가 부담금을 추가 납부할 경우 위험자산의 최적 투자 비중은 큰 폭으로 하락하였으며, 이러한 효과는 저소득자에서 크게 나타났다. 따라서, OECD 평균 수준의 소득대체율을 달성하기 위해 정부는 가입자들이 일정 수준 이상의 적립금을 위험자산에 투자할 수 있도록 유인하는 가운데 저소득층에게는 추가부담금 납입을 유인하기 위한 보조금 정책 등을 검토할 필요가 있다.

• 산업경영시스템학회지
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• 제43권1호
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• pp.61-69
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• 2020

Systems such as database and socal network systems have been broadly used, and their unexpected failure, with great losses and sometimes a social confusion, has received attention in recent years. Therefore, it is an important issue to find optimal maintenance plans for such kind of systems from the points of system reliability and maintaining cost. However, it is difficult to maintain a system during its working cycle, since stopping works might incur users some troubles. From the above viewpoint, this paper discusses minimal repair maintenance policy with periodic replacement, while considering the random working cycles. The random working cycle and periodic replacement policies with minimal repair has been discussed in traditional literatures by usually analyzing cases for the nonstopping works. However, maintenance can be more conveniently done at discrete time and even during the working cycle in real applications. So, we propose that periodic replacement is planned at discrete times while considering the random working cycle, and moreover provide a model in which system, with a minimal repair at failures between replacements, is replaced at the minimum of discrete times KT and random cycles Y. The average cost rate model is used to determine the optimal number of periodic replacement.

• 대한족부족관절학회지
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• 제18권4호
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• pp.195-201
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• 2014

Purpose: The purpose of this study is to develop guidelines for clinical trial of the total ankle replacement system for premarket approval. Materials and Methods: We selected and analyzed nine peer-reviewed articles whose quality had been proven in a previous phase. Two investigators extracted parameters for guideline criteria, including number of cases, patient age, follow-up period, failure rate, radiographic osteolysis rate, residual pain rate, and percentage of satisfaction. In addition, the inclusion and exclusion criteria were analyzed and developed. Results: Eight level IV studies and one level II study were included. The average number of cases was 159 cases and the mean patient age was 63.5 years. The mean follow-up period was 4.2 years, ranging from two to nine. The average failure rate of total ankle replacement in mid- to long-term follow-up was approximately 13% (2%~32.3%). The rate of osteolysis was approximately 18%. Residual pain was common (21.4%~46%), but overall patient satisfaction was approximately 85.6% (67.5%~97%). Conclusion: The results could be used as criteria for designing the clinical studies, such as number of cases, patient age (over 60 years), and follow-up period (minimum two years). The clinical scoring system and 36-item short form health survey (SF-36) was the most commonly used method for clinical evaluation for total ankle arthroplasty. In addition, the overall results, including failure rate, osteolysis rate, and patient satisfaction, could be used as a parameter of guidelines for premarket approval.

• Journal of Construction Engineering and Project Management
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• 제1권3호
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• pp.28-37
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• 2011

Domestic construction companies are suffering from financing difficulties in the wake of the economic slump in Korea and abroad. During this economic slump, real estate investment trusts (REITs), facilitators for improving financing and stimulating construction businesses, have increasingly expanded since their introduction in 2001. However, in terms of growth speed and marketing size, Korean REITs are falling behind those of other nations. The purpose of this study is to suggest a method for composing a portfolio using the Markowitz portfolio selection model to stimulate REITs. The main contents are as follows. First, a comparative analysis was conducted of increased REIT profit with the application of the Markowitz model and the average REIT profit rate from July 3, 2007, to July 21, 2008, during the investment analysis periods. The results showed that the total profit rate from the Markowitz model was about 10% higher than the average REIT profit rate. Second, the sensitivity was analyzed according to the portfolio's data-gathering and replacement cycle to measure the optimum cycle and yield. The six-mouth profit data collection period showed about 16% higher profits with the Markowitz model than with the REITs. The two-week portfolio change period resulted in about 11% higher profits with the Markowitz model than with the REITs.

• 청정기술
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• 제12권4호
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• pp.238-243
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• 2006

본 연구에서는 용융 전로슬래그를 고속의 공기를 이용하여 급랭한 전로슬래그의 골제 특성을 조사하고 이를 잔골재로 재활용한 모르타르의 특성을 분석하였다. 급랭전로슬래그의 입자형태는 구형이었으며 냉각 속도의 차이로 인해 표면층과 내부층 그리고 외부와 연결된 공동을 가지고 있었다. 표준사를 구형 급랭전로슬래그로 대체한 혼합 잔골재의 특성을 분석한 결과 대체 비율이 증가하면서 비중, 단위용적중량 그리고 조립율이 증가하였으며 실적률은 대체 비율 75%에서 최대를 나타내었다. 흡수율은 대체 비율 50%에서 최소값을 보였다. 혼합 잔골재의 구형 급랭전로슬래그 대체 비율이 증가할수록 굳지 않은 모르타르의 유동성이 증가하여 동일한 플로우값을 얻기 위한 물/시멘트 비는 감소하였다. 구형 급랭전로슬래그 대체 비율이 증가할수록 양생한 모르타르 시편의 조직은 치밀하였으며 비중은 증가하였다. 압축강도의 경우는 대체율 75%에서 최대값을 보였다.

• 한국수자원학회논문집
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• 제42권7호
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• pp.525-535
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• 2009

본 연구에서는 상수관망에서 개별적으로 노후도가 심하여 개량이 필요한 구간을 보다 정확하게 구분하기 위해 새로운 개별관로 정의 방법이 개발되었다. 적절한 관로 최소구성성분 길이를 결정하기 위하여 여러 가지 관로 최소구성성분 길이에 대한 평균 누적파손횟수경사선의 분산값을 비교하여 가장 큰 분산값을 나타내는 관로 최소구성성분 길이인 4 m 를 연구대상 지역의 상수관망에 적용하였으며 관로 ID는 39개로 구분되어졌다. 관로의 경제적 최적교체 시기는 한계파손율과 관로의 파손경향모형을 이용하여 결정되었는데, 각 관로 ID에 대하여 관로의 선형적 파손경향, 지수적 파손경향 또는 선형과 지수형 사이에 있는 파손경향 모두에 적용될 수 있는 General Pipe Break Prediction Model(Park and Loganathan, 2002)과 수정된 시간척도를 이용한 ROCOF(Park et al., 2007)를 적용하여 연구대상 상수관망의 최적교체시기를 산정 및 분석하였다. ROCOF 모형화 과정에서 대수-선형과 와이블 ROCOF를 적용 후 최대로그우도 추정값을 비교하여 최대로그우도가 큰 값을 가지는 ROCOF를 각 관로 ID의 ROCOF로 사용하였다. 관로파손으로 인한 사회적 비용이 관로의 최적교체시기에 미치는 영향도 분석되었다.