• Journal of the Korean GEO-environmental Society
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• v.20 no.11
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• pp.11-22
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• 2019

Limit state design (LSD) and allowable stress design (ASD) are two main types of soil nailing design methodologies. In the LSD method, stability is determined by applying individual coefficients to ground strength, working load and etc. The ASD method calculates the safety factor and compares it with the minimum safety factor to determine the stability. The global design trend of soil nailing system is changing from the ASD method to the LSD method. The design method in Korea still adopts the ASD philosophy while others mostly do the limit state design. In this study, four soil nail design methods, 'FHWA GEC 7' in U.S. (2015), 'Clouterre' in France (1991), 'Soil nailing - best practice guidance' in U.K. (2005), 'Geoguide 7' in Hongkong (2008), and 'Design guide for slope in construction work' in Korea (2016) were applied to the evaluation of the stability and the results were analyzed comparatively in brief. It is revealed that the design method of 'the overall stability of soil nail walls' in Korea is the most conservative and next those by FHWA, Clouterre and CIRIA become more conservative in order. However, the difference of results obtained from FHWA and Clouterre is negligible. Also, this study found out that efforts to improve domestic design criterion are needed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.212-221
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• 2022

In this paper, the evaluation procedure applying the limit state design method is studied to be consistent with the newly issued bridge design code in Korea. The live load factor for evaluation is proposed by calibrating for the target reliability index through reliability analysis. Using the actual bridge information collected for the representative bridge types in Korea, the load effects of the design live loads for the previous and current design codes are calculated and compared. The live load factor is calibrated through reliability analysis using the minimum required strength which equals to the load effect obtained for the example bridge. Bridge evaluation is performed by applying the live load factors for the evaluation level as well as design level. The load rating result is generally increased by applying the limit state design method compared to the previous design method and applying the proposed load factor for lowered target reliability index further increased the rating result.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.494-503
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• 1986

본 연구에서는 저강도.고연성재인 일반구조용압연강 SB41의 평골 CT 시험편과 양측면홈이 있는 CT시험편을 사용하여 ASTM R유선법, JSME R유선법,SZW법, 초음파법 및 전입차법에 따라 J$_{IC}$를 종합적으로 평가하였다. 복수시험편법인 ASTM 및 JSME 및 JSME R유선법을 상호 비교고찰하므로써 저강도.고연성재에 대한 파환인성평가 의 적용한계를 명확히 하였으며 단일시험편법인 초음파 및 전입차시험법은 효율적이고 간편한 J$_{IC}$평가법임을 확인하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2004.11a
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• pp.70-75
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.344-349
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• 1998

고리 1호기 원전의 원자로냉각재 배관의 파단전누설개념 적용성을 평가하기 위하여 일반적인 파단전누설 절차 및 기준을 검토하였다. 파단전누설 타당성을 검토하기 위하여는 한계하중방법 및 J-T 방법을 비교검토 하였다. 그리고 원자로냉각재 배관에 대해서는 탄소강일 경우와 스테인레스강에 대하여 분석하였고, 가압기 밀림관에 대해서는 열응력을 계산하였다. 그리고 원자로 냉각재 배관에 가상의 관통균열의 파괴안전성은 유한요소법을 이용한 탄소성파괴역학을 통하여 분석하였다. 분석결과 한계하중법과 J-T 방법 모두 스테인레스강과 탄소강재질에 대해 적용 가능한 것으로 나타났다.

• Journal of Ocean Engineering and Technology
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• v.1 no.1
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• pp.94-103
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• 1987

균열불안정 해석법인 COD설계곡선법과 R6파괴 평가도법에 있어서 그 응용 한계의 확립과 타당성 수준의 정량화를 위해 포괄적인 비교 연구가 수행되었다. 참고로서 J-적분 균열불안정성 해석법이 이용되었다. 본 연구의 결과로서, 균열확장의 유무에 대한 R6 파괴 평가도법이 매우 우수한 방법임을 보여준다. COD 설계곡선법에 대한 영국 표준국 순서에 따른 결과로서는, 큰 스캐터 밴드를 가진 상당량의 부당성 해를 보여준다. 이러한 COD설계곡선법의 해를 개선하기 위한 새로운 접근법이 개발되었고, 그 타당성이 입증되었다.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.5-15
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• 2014

Target reliability index in the limit state design indicated the safety margin and it is important to determine the partial factor. To determine the target reliability index which is needed in the limit state design, the six design and construction case histories of gravel compaction piles (GCP) were investigated. The limit state functions were defined by bulging failure for the major failure mode of GCP. The reliability analysis were performed using the first order reliability method (FORM) and the reliability index was calculated for each ultimate bearing capacity formulation. The reliability index of GCP tended to be penportional to the safety factor of allowable stress design and average value was ${\beta}$=2.30. Reliability level that was assessed by reliability analysis and target reliability index for existing structure foundations were compared and analyzed. As a result, The GCP was required a relatively low level of safety compared with deep and shallow foundations and the currd t reliability level were similar to the target reliability in the reinforced earth retaining-wall and soil-nailing. Therefore the target reliability index of GCP suggested as ${\beta}_T$=2.33 by various literatures together with the computed reliability level in this study.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2001.03a
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• pp.97-108
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• 2001

절리가 발달한 암반의 거동평가를 위한 해석적 방법은 연속체 모델과 불연속체 모델을 사용하는 방법으로 대별할 수 있으며, 연속체 모델을 사용할 경우에는 유한요소법이나 유한차분법을 이용하는 방법이 주종을 이루고 있다. 불연속체 모델은 개별 블록들의 움직임을 일일이 계산하므로 매우 매력적인 방법이지만 현재의 지반조사 기술수준으로는 지반내의 절리발달사항을 정확히 파악하기가 매우 어려우며, 컴퓨터의 계산용량이 너무 과다해지는 단점이 있다. 따라서, 불연속면을 포함한 암반을 연속체로 가정한 편재절리 모델(ubiquitous joint model)을 이용한 연구가 요구된다. 한편, 터널의 경우는 사면의 경우와는 달리 파괴면의 형상을 사전에 가정하기 어렵기 때문에 한계평형법에 기초한 해석법 등을 적용하여 안전율을 구하기가 곤란하다. 이러한 이유에서 터널을 대상으로 한 수치해석은 안전율을 구하기보다는 안정성을 평가하는 데만 제한적으로 사용되어 왔다. 본 논문에서는 편재절리모델을 이용한 절리암반터널의 거동 평가기법과 수치해석에 의해 터널의 안전율을 구하는 방법을 제시하는 데에 그 목적이 있다. 이를 위해 터널의 안전율 구하는 방법을 강도감소기법에 근거하여 제시하였다.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.286-289
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• 1998

일찍부터 직물의 구김형성과 회복에 관한 연구[1~4]는 꾸준히 계속되고 있으며, 이에 따른 여러 가지 실험방법도 많이 소개되고 있다. 앞서 연구된 방법들은 구김의 정도를 판정하는데 있어서 1970년대까지는 구김의 순위 판정법을 이용하여 주관적인 상대 평가법으로 하였으므로 관측자의 주관적 한계성을 극복하지 못한 면이 있다. (중략)

• Journal of Food Hygiene and Safety
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• v.37 no.3
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• pp.136-142
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• 2022

The research aims to develop a rapid and easy analytical method for methoprene using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A simple, highly sensitive, and specific analytical method for the determination of methoprene in livestock products (beef, pork, chicken, milk, eggs, and fat) was developed. Methoprene was effectively extracted with 1% acetic acid in acetonitrile and acetone (1:1), followed by the addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium acetate. Subsequently, the lipids in the livestock sample were extracted by freezing them at -20℃. The extracts were cleaned using MgSO₄, primary secondary amine (PSA), and octadecyl (C₁₈), which were then centrifuged to separate the supernatant. Nitrogen gas was used to evaporate the supernatant, which was then dissolved in methanol. The matrix-matched calibration curves were constructed using 8 levels (1, 2.5, 5, 10, 25, 50, 100, 150 ng/mL) and the coefficient of determination (R²) was above 0.9964. Average recoveries spiked at three levels (0.01, 0.1, and 0.5 mg/kg), and ranged from 79.5-105.1%, with relative standard deviations (RSDs) smaller than 14.2%, as required by the Codex guideline (CODEX CAC/GL 40). This study could be useful for residue safety management in livestock products.