• 대한기계학회논문집A
• /
• 제29권11호
• /
• pp.1488-1493
• /
• 2005

In this study, fatigue tests to obtain S-N curves and FE analyses to obtain structural stress concentration factors were conducted for the two types of cruciform fillet welded joints, that is, load-carrying and non load-carrying types. Then we changed the obtained S-N curve of load carrying joint to that based on hot spot stress. As a result, the S-N curve of load carrying joint based on hot-spot stress was almost exactly coincided with that of non load-carrying joint based on nominal stress. So we have conducted that the fatigue strength of a welded joint with different geometry from the non stress distribution along the expected crack path.

• Wind and Structures
• /
• 제16권6호
• /
• pp.629-660
• /
• 2013

This paper reviews the current state-of-the-art in the numerical evaluation of wind loads on buildings. Important aspects of numerical modeling including (i) turbulence modeling, (ii) inflow boundary conditions, (iii) ground surface roughness, (iv) near wall treatments, and (vi) quantification of wind loads using the techniques of computational fluid dynamics (CFD) are summarized. Relative advantages of Large Eddy Simulation (LES) over Reynolds Averaged Navier-Stokes (RANS) and hybrid RANS-LES over LES are discussed based on physical realism and ease of application for wind load evaluation. Overall LES based simulations seem suitable for wind load evaluation. A need for computational wind load validations in comparison with experimental or field data is emphasized. A comparative study among numerical and experimental wind load evaluation on buildings demonstrated generally good agreements on the mean values, but more work is imperative for accurate peak design wind load evaluations. Particularly more research is needed on transient inlet boundaries and near wall modeling related issues.

• 수산해양기술연구
• /
• 제18권1호
• /
• pp.17-23
• /
• 1982

한국국적의 유조선 35척의 외판 및 격벽의 부식도를 선령별로 조사한 결과를 요약하면 다음과 같다. 1. 선령 12년급의 외판의 평균부식도는 경흘수선 및 하부 만곡부선에서는 선수부가, 건현 및 상부만곡부선에서는 중앙부가, 양재흘수선에서는 선미부가 가장 높다. 2. 선령 20년급의 외판의 평균부식도는 경흘수선 및 상.하부만곡부선에서는 선수부가, 건현중앙선에서는 중앙부가, 만재 흘수선에서는 선미부가 가장 높다. 3. 측수조와 중앙유조의 횡격벽의 평균부식도는 어느 선령에서나 정부선, 상부선, 중앙선에서는 측수조가 높고, 하부선과 저부선에서는 중앙유조가 높다. 4. 중앙유조와 양측 유조의 횡격벽부식도 어느 선령에서나 중앙유조의 횡격벽 쪽이 높다. 5. 중앙유조의 종.횡격벽의 부식도는 격벽의 중앙선상부에서는 어느 선령에서나 종벽부 쪽이 높다. 6. 내부수조 및 중앙유조의 횡격벽과 같은 높이에 있는 선각외판의 건현부의 평균부식도를 비교하면, 격벽상부의 부식도가 외판의 그것보다 크다.

• 한국해양학회지
• /
• 제10권2호
• /
• pp.67-75
• /
• 1975

Tidal Flushing at the entrance channels of tidal bay or estuary in the central western coast of Korea; Gum River Estuary, Garorim Bay, Asan Bay, and Yeomha Estuary were studied with the recent data of current surveys measured by curret meter at three or five anchored stations along the section for one or two tidal periods at mean spring tide. Equilibrium relationship between tidal prism at mean spring tide and minimum flow area below the mean sea level of the channel in alluvial material was found as of O'Brien's (1931, 1969) study. Bed load transport in the tidal channel is balanced with the tidal flushing ability having a mean velocity of about 0.75m/sec or maximum velocity of about 1.25m/sec for a half tidal cycle over the section at mean spring tide which fairly agree with Brunn's study(1955, 1957). flushing actions for different hydraulic depth( mean depth) and bed material size in the channel were reviewed and found that it depend to a minor extent on the factors.

• 한국철도학회논문집
• /
• 제8권1호
• /
• pp.15-20
• /
• 2005

The ministry of Environment, Korea, are designing the TMDL(Total Maximum daily Load) program far 4 major large rivers to improve water quality from possible pollutants. It can be successfully performed as controling of nonpoint pollutants from watershed area. Railway stations are stormwater intensive land use because of high imperviousness and high pollutant mass emissions from various activities. Especially the metal pollutants from the railway station were recognized as an important pollutants because of its toxicities. In order to characterize the washed-off pollutants. the monitoring were performed on a railway station during storms. Pollutant concentrations are exponentially decreasing during the storm duration. The 95％ confidence interval of pollutant concentrations in an hour storm duration ranges from 61.6 to 115.4mg/L for TSS(mean=88.50mg/L),103.8-244.1mg/L for COD(mean=174 mg/L) and 7.68-17.32mg/L for Oil & Grease(mean=12.5mg/L). The ranges of metals were 39.2-84.0 $\mu\textrm{g}$/L for total Cu(mean=61.6$\mu\textrm{g}$/L), 14.0-25.8$\mu\textrm{g}$/L for total Pb(mean=19.9$\mu\textrm{g}$/L) and 182.2-376.l $\mu\textrm{g}$/L for total Zn(mean=279.2$\mu\textrm{g}$/L). The first flush criteria for best management practices can be suggested to 50％ pollutant mass emissions during 30％ of the total flow.

• 드라이브 ㆍ 컨트롤
• /
• 제19권4호
• /
• pp.29-35
• /
• 2022

In this paper, we developed a workload index for monitoring the durability test using operation information of an excavator. First, the acceleration and cylinder pressure were selected as load factors by analyzing operation data. Through load correlation analysis according to each load factor, Root Mean Square (RMS) and Work Load Range (WLR) were respectively derived as a load feature representing mechanical load. In addition, the workload index was used to quantify load features. For applying the workload index to monitoring, a real-time monitoring system consisting of sensors and embedded controller was installed on the excavator and the system was integrated with a remote monitoring environment using a wireless network. Results of load monitoring and analysis verified that the developed workload index was effective from the viewpoint of the relative comparison of the workload.

• International journal of advanced smart convergence
• /
• 제11권3호
• /
• pp.1-6
• /
• 2022

In this paper, we estimate the mean number of objects in the M/H₂/1 model for web service when the mean object size in the M/H₂/1 model is equal to that of the M/G/1/PS and M/BP/1 models. To this end, we use the mean object size obtained by assuming that the mean latency of deterministic model is equal to that of M/H₂/1, M/G/1/PS, and M/BP/1 models, respectively. Computational experiments show that if the shape parameter of the M/BP/1 model is 1.1 and the system load is greater than 0.35, the mean number of objects in the M/H₂/1 model when mean object size of M/H₂/1 model is the same as that of M/G/1/PS model is almost equal to the mean number of objects in the M/H₂/1 model when the mean object size of M/H₂/1 model is the same as that of M/BP/1 model. In addition, as the upper limit of the M/BP/1 model increases, the number of objects in the M/H₂/1 model converges to one, which increases latency. These results mean that it is efficient to use small-sized objects in the web service environment.

• 조명전기설비학회논문지
• /
• 제18권5호
• /
• pp.105-111
• /
• 2004

본 논문에서는 실제 전력 수요 데이터를 이용하여 유효전력에 단기 부하 예측함에 있어 무효전력이 중요한 역할을 하는 것을 회귀 분석 검정 통계량으로 증명한다. 무효전력의 공급과 수요는 계통의 전압과 아주 밀접한 관계를 가지고 있으므로 계통전압을 관리하고 계통의 신뢰도를 높이기 위해서는 예측된 무효전력 수요에 따라 무효전력 공급계획을 별도로 수립하여 운영해야 한다. 따라서 본 논문에서는 다중 시계열 모델을 이용한 시전 예측방법을 이용하여 설명변수로 유효전력을 사용하여 부하의 무효전력을 예측 하였다.

• 한국철도학회논문집
• /
• 제13권1호
• /
• pp.31-36
• /
• 2010

본 연구에서는 직조된 탄소/에폭시 판재와 알루미늄 허니콤 심재를 갖는 샌드위치 복합소재 정사각 튜브의 압축하에서 허니콤 셀 크기의 효과를 규명하였다. 이를 위해, 4종류의 사각튜브가 제작되고 10mm/min의 준정적 하중하에서 200mm~250mm까지 압축하였다. 본 연구에서는 6.35mm와 9.53mm의 셀 크기를 갖는 알루미늄 허니콤에 사용되었다. 평균압축하중과 셀 크기의 관계가 규명되었고, 평균압축하중에 대한 판재와 허니콤의 접착강도(peel strength)와 리본방향의 등가탄성계수의 영향을 분석하였다.

• 한국공작기계학회논문집
• /
• 제17권1호
• /
• pp.86-91
• /
• 2008

The structural members must be designed to control characteristics of energy absorption for protecting passengers in a car accident. Study on collapse characteristics of structural member is currently conducted in parallel with other studies on effective energy absorption capacity of structural members with diverse cross-sectional shapes and various materials. This study concerns the crashworthiness of the widely used vehicle structural members, square thin-walled tubes, which are excellent in the point of the energy absorption capacity. The absorbed energy, mean collapse load and deformation mode were analyzed for side member which absorbs most of the collision energy. To predict and control the energy absorption, controller is designed in consideration of its influence on height, thickness and width ration in this study. The absorbed energy and mean collapse load of square tubes were increased by $15{\sim}20%$ in using the controller, and energy absorbing capability of the specimen was slightly changed by change of the high controller's height.