For a member model in nonlinear structural analysis, a lumped plastic model that idealizes its flexural bending, shear, and axial behaviors by springs with the nonlinear hysteretic model is widely adopted because of its simplicity and transparency compared to the other rigorous finite element methods. On the other hand, a challenging task in its numerical solution is to satisfy the equilibrium condition between nonlinear flexural bending and shear springs connected in series. Since the local forces between flexural and shear springs are not balanced when one or both springs experience stiffness changes (e.g., cracking, yielding, and unloading), the additional unbalanced force due to overshooting or undershooting each spring force is also generated. This paper introduces an iterative scheme for numerical solutions satisfying the equilibrium conditions between flexural bending and shear springs. The effect of equilibrium iteration on analysis results is shown by comparing the results obtained from the proposed method to those from the conventional scheme, where the equilibrium condition is not perfectly satisfied.

Nonalcoholic fatty liver disease (NAFLD) is recognized one of the leading metabolic diseases globally, and the younger age population with the disease is rapidly growing, especially in developed countries. Since there has been no approved medicine, losing weight is known to be the only best remedy to control or reverse the disease. Recently, the field of microbiome has attracted much attention to offer more practical choices for patients. Here, we provide experimental evidence that Streptococcus thermophilus LM1012 (LM1012), a safe probiotic strain, is effective for improving NAFLD indexes. In the methionine-choline deficient (MCD) diet induced C57BL/6 mouse model, administration of LM1012 promoted marked reductions of aspartate transaminase (23.8%), total bilirubin (27.8%), hydroxycholesterol (64.2%), triglyceride (29.7%) and IL-1β (68.3%) compared to the MCD diet alone group. Also, the histopathological data imply that LM1012 inhibited fat accumulation and inflammation in the liver, which are the key biomarkers for progression of the disease. Together, these findings suggest that human consumption of LM1012 as a healthy nutritional supplement, may be helpful in reducing the risk of liver damages in NAFLD patients.

본 연구에서는 한중 FTA로 인하여 우리나라 대중 농산물 수입액이 어떠한 영향을 받았는 지를 품목별 미시자료와 다기간 이중차분모형을 적용하여 분석하였다. 2010년부터 2019년까지 FAO (Food & Agriculture Organization)의 품목별 대중 농산물 수입액과 연도별 양허 자료를 이용하여 2015년 이후 한중 FTA로 인한 품목별 양허가 우리나라 대중 농산물 수입액에 미친 영향을 분석하였다. 연도별 양허효과가 동일하다고 가정하면 양허로 인하여 양허대상 품목이 약 680~693만 불의 수입 증가 효과가 존재하고 있었다. 그리고 연도별 양허효과가 상이하다고 가정하면 2016년, 2017년 및 2019년은 양허대상 품목의 수입증가 효과가 통계적으로 유의한 것으로 나타났지만 2018년은 통계적 유의성이 낮았다.

전 세계적으로 해상을 마주하고 있는 여러 국가들은 기존의 전력 생산방식의 단점을 극복하고 해상풍력 개발을 통한 친환경에 너지자원을 활용하고 있다. 해상은 넓은 해역에 대규모 풍력단지를 개발할 수 있는 장점이 있으나 해양구조물의 설치로 인해 선박의 안 전운항이 위협받고 있다. 이에 따라, 선박 통항로와 해상풍력단지 간 상호 미치는 영향에 대해 분석하여 선박이 안전하게 운항할 수 있도 록 PIANC에서는 표준 Guideline을 제시하였다. 그럼에도 불구하고, 표준 Guideline은 모든상황에서 동일한 이격거리를 산정하였다. 따라서 본 연구에서는 선회성능, 조우상태, 환경외력, 해상밀집도, 해상풍력발전기, 항로형태 등을 요소로 반영한 선박 통항로와 해상풍력단지 간 최적의 이격거리 산정 모델을 개발하였다. 개발된 모델 검증을 위한 시뮬레이션 결과, 운항 준비상태에 따른 입지 특성별 선회성능 크기 는 산정 모델에서 제시한 크기와 유사하였다.

The Moving Particle Semi-implicit (MPS) method is one of most famous method in the particle-based computational fluid dynamics field. The MPS, the state-of-art method, is simple but intuitive methodology including multi-phase and complex structure interactions problems. However, the concept of particle method may contain the physical weakness. In order to avoid physical violence, the particle number density and kernel function were employed. Despite all the efforts, the microscopic problems were not easily resolved yet. In this study, the surface tension model was developed and added into the MPS method to strengthen physical phenomena and physics laws. The simulation result with new MPS method including surface tension model was compared with corresponding theoretical results and they show good-agreement.

본 연구의 목적은 과거 12년(2010~2021년)간 발생한 상선의 충돌사고 668건을 조사하여 충돌의 원인요인을 조사하고 이를 통계 적으로 분석하여 항해사의 인적과실 예방 충돌회피(HEPCA) 모델을 제안하는 것이다. 중앙해양안전심판원의 통계연보 및 충돌사건 재결서 를 조사하여 상선의 충돌 원인요인 데이터를 수집하고 통계분석 도구인 SPSS를 이용하여 빈도분석을 수행하였다. 1단계 분석으로 상선 충 돌사고 668건을 대상으로 충돌원인을 분석하였고, 2단계 분석에서는 식별된 최대빈도 원인요인을 세부적으로 분석하였다. 분석결과, 충돌 원인은 항해사의 인적과실이 98 %인 것으로 식별되었으며, 빈도 높은 요인 순서는 경계소홀 〉항행법규위반 〉조선 부적절 순이었다. 경계 소홀의 원인 요인은 주로 상대선 초인 후 지속감시 소홀이었으며 상대선박의 존재를 인식하지 못한 원인은 주로 당직시간에 다른 작업을 한 요인이었다. 분석결과를 적용하여 인적과실 예방을 위한 HEPCA 모델을 제안하였고, 이를 재결서의 충돌사건에 적용해보았다. 본 연구결과는 해기사 교육기관 및 실무에서 항해사의 인적과실로 발생하는 충돌사고를 방지하기 위한 교육 자료로 활용이 가능할 것으로 기대된다.

Ball stud parts are manufactured by a cold forging process, and fastening with other parts is secured through a head part cutting process. In order to improve process quality, stabilization of the forging quality of the head is given priority. To this end, in this study, a predictive model was developed for the purpose of improving forging quality. The prediction accuracy of the model based on 450 data sets acquired from the manufacturing site was low. As a result of gradually multiplying the data set based on FE simulation, it was expected that it would be possible to develop a predictive model with an accuracy of about 95%. It is essential to build automated labeling of forging load and dimensional data at manufacturing sites, and to apply a refinement algorithm for filtering data sets. Finally, in order to optimize the ball stud manufacturing process, it is necessary to develop a quality prediction model linked to the forging and cutting processes.

This study compares and analyzes the drogue shape applied to aerial refueling with the U.S. Navy drog shape through basic analysis of the model based on the flying fish shape, a marine creature. Flying fish is a creature that is advantageous for non-powered downhill, and this shape is applied to the probe feeding method to minimize the burden on the pilot and the need for refueling technology, which are disadvantages of the probe method. To this end, the results through analysis of basic studies were confirmed, and the superiority and insufficiency of the flying fish shape model and the US Navy drogue model were compared. Therefore, as confirmed through analysis, the flying fish model had a 14.1% lower maximum air pressure and a 9.1% faster maximum speed. Based on this, it is hoped that the advantages and disadvantages of flying fish shape models will be confirmed through actual flight tests in the future.

The lane departure warning device can not detect the lane to be driven in the future by sensing the departure of the lane passing by during driving and warning the driver. Considering the safe operation of the truck, it is also expected that the departure of the future lanes according to the dynamic weight and speed of the current truck should be predicted. This study attempted to predict whether or not to deviate from the lanes of curved roads to be driven in the future according to the current dynamic driving weight and speed in consideration of the safe driving of trucks.

국내외로 첨단 ICT 융합기술이 농업 분야에 적용되기 시작 하면서, 시설원예 설비들이 고도화되고, 스마트팜 구축 기술 및 인력이 축적되기 시작하였다. 그러나 우리나라 농촌의 경 우, 농업생산 연령의 고령화, 국내 농촌 인구의 지속적인 유출, 저출산 등으로 인하여 스마트팜 확대 및 적용에 어려움이 많 은 실정이다. 따라서 공간 및 시간에 구속을 받지 않는 간편한 농업인 교육 프로그램이 필요하며, 최근 부상하고 있는 시뮬 레이션 기술을 활용한다면 농업 교육용 시뮬레이션 툴 개발도 가능할 것으로 판단된다. 온실 환경 제어 모델을 이용한 시뮬 레이션은 다양한 지역과 기상 조건 하에서 대상 온실의 열과 물질에너지의 상호작용을 합리적으로 예측할 수 있게 해준다. 본 연구에서는 온실 환경 제어 모델을 활용하여 외부 기상 데 이터를 통해 온실의 환경 변화를 예측하고 가상의 환경 제어시스템을 통해 환경 제어 시 필요한 에너지값들을 시뮬레이션 할 수 있었다. 이러한 결과를 통해 이용자가 직접 맞춤형 환경 제어를 할 수 있도록 편의성을 고려한 사용자 인터페이스를 구축할 것이며, 실제 파프리카 재배 온실의 제어 요소들을 반 영할 수 있도록 설계될 것이다. 농업용 교육 시뮬레이션 툴을 최근 활발하게 연구가 이루어지고 있는 작물 생육 모델링 기 술 및 전산유체역학 기술과 융합하면 더욱 타당한 결과를 보 일 것이다.

As part of the third ATM Challenge, we performed a series of atmospheric dispersion simulations for routine releases of Xe-133 from ordinarily operating nuclear facilities such as Medical Isotope Production Facilities (MIPFs), Nuclear Power Plants (NPPs), and Research Reactors (RRs) in the Northern Hemisphere using our ATM, Lagrangian Atmospheric Dose Assessment System (LADAS), with Numerical Weather Prediction (NWP) data produced by the Korea Meteorological Administration (KMA). The simulation time period is 6 months, from June to November in 2014, and we used the stack emission data except for CNL (Canada) and IRE (Belgium) in accordance with the scenario of the third ATM Challenge 2019. In addition, the simulations were done individually for all MIPFs, NPPs, and RRs. We utilized 3-hourly KMA’s Unified Model Global Data Assimilation and Prediction System (UM-GDAPS) data with 0.35°×0.23° horizontal resolution as input meteorological fields and extracted hourly time series results for Xe-133 activity concentrations with few different resolutions such as 0.5°×0.5°, 0.35°×0.23°, and 0.1°×0.1° at several IMS stations in the Northern Hemisphere which were in normal operation in 2014. Considering previously reported values of daily Xe-133 release amounts for CNL and IRE, measured signals at some IMS stations (such as CAX17, DEX33, SEX63, and USX75) were well reproduced from the simulation results.

Considering the Fukushima nuclear accident and the marine discharge plan of contaminated (or treated) water, it is necessary a seafood monitoring system for radioactive material screening. Currently, radioactivity tests in seafood are conducting in Korea. Although current method using a HPGe detector can provide very low uncertainty in determining radioactivity, there is a limitation in that rapid inspection cannot be performed because of a time-consuming pretreatment process as well as long measurement time (typically 10,000 s). To overcome this limitation, we are developing an insitu inspection device, a kind of screening system, which can monitor the radioactivity in seafood in a near real-time basis. In this study, the actual seafood with a check source was measured to verify the reliability of the Monte Carlo simulation model. The detector used in the experiment was a 5-cm-thick polyvinyl toluene (PVT) plastic scintillator with a 0.5-cm-thick lead shield for background reduction. A Cs-137 check source was placed within seafood. The seafood used in the experiment was fishcake, raw oyster, and dried laver, which is the representative seafood of fish, shellfish, and seaweed. These three seafood products of the same size and shape as the manufacturing process were used to predict the performance realistically. We compared the energy spectrum of the Cs-137 check source obtained from measurements and simulations. The region of interest (ROI) around the Compton edge was set to reduce the influence of the background and electronic noise. The results showed that the measured and simulated spectrum were in good agreement.

A simulation model was developed for heavy water pre-enrichment and detritiation by the Combined Electrolysis and Catalytic Exchange (CECE) process. In the CECE process, heavy water enrichment and detritiation are based on the principle that concentrated in to water phase through an isotopic exchange reaction between water vapor and hydrogen gas produced by a water electrolysis. An operational analysis for a liquid phase catalytic exchange column was carried out by the model equations, composed of a material balance and combined equilibrium relationships for a scrubbing and catalyst bed, respectively. As a result of simulation, the optimum flow ratio of water to the rising hydrogen gas in contact with the down-coming water was predicted as the key variables in the separation performance analysis at a given feed flow rate and isotopic composition. From a graphical approach based on this model, the operating conditions can be determined within the range where the operating line does not meet the combined equilibrium line before reaching the specified target concentration.

Molten Salt Reactor, which employs molten salt mixture as fuel, has many advantages in reactor size and operation compared to conventional nuclear reactor. In developing Molten Salt Reactor, Offgas system should be properly designed since the fission products in off-gas accelerates the corrosion in reactor structure materials and deteriorates the purity of liquid fuel. The design of off-gas system therefore requires the preliminary study of the behavior of evolved fission products in off-gas units and the development of off-gas model is crucial in developing such system. In this study, we corrected the off-gas illustrative model proposed by ORNL (Nuclear Engineering and Design, vol 385(15) 111529, 2021) by employing physically consistent concept of capture rate of fission product and holdup. For the application of the corrected off-gas model to Chloride-based 6 MW Molten Salt Reactor, major fission products were firstly determined from OpenMC based neutronics calculation and chain reaction related to the major fission products were defined. Based on these data, the holdup behavior of fission products in off-gas units (decay tank, caustic scrubber, Halide trap, H2O trap and charcoal bad) were investigated.

The analysis of uranium migration is crucial for the accurate safety assessment of high-level radioactive waste (HLW) repository. Previous studies showed that the migration of the uranium can be affected by various physical and chemical processes, such as groundwater flow, heat transfer, sorption/ desorption and, precipitation/dissolution. Therefore, a coupled Thermal-Hydrological-Chemical (THC) model is required to accurately simulate the uranium migration near the HLW repository. In this study, COMSOL-PHREEQC coupled model was used to simulate the uranium migration. In the model, groundwater flow, heat transfer, and non-reactive solute transport were calculated by COMSOL, and geo-chemical reaction was calculated by PHREEQC. Sorption was primarily considered as geo-chemical reaction in the model, using the concept of two-site protolysis nonelctrostatic surface complexation and cation exchange (2 SP NE SC/CE). A modified operator splitting method was used to couple the results of COMSOL and PHREEQC. Three benchmarks were done to assess the accuracy of the model: 1) 1D transport and cation exchange model, 2) cesium transport in the column experiment done by Steefel et al. (2002), and 3) the batch sorption experiment done by Fernandes et al. (2012), and Bradbury and Baeyens (2009). Three benchmark results showed reliable matching with results from the previous studies. After the validation, uranium 1D transport simulation on arbitrary porewater condition was conducted. From the results, the evolution of the uranium front with sequentially saturating sites was observed. Due to the limitation of operator splitting method, time step effect was observed, which caused the uranium to sorbed at further sites then it should. For further study, 3 main tasks were proposed. First, precipitation/ dissolution will be added to the reaction part. Second, multiphase flow will be considered instead of single phase Darcy flow. Last, the effect of redox potential will be considered.