For safety assessment of a high-level radioactive waste disposal system, it is important to predict and analyze the coupled thermo-hydro-mechanical (THM) behaviors of bentonite, which is a buffer candidate material in the engineered barrier system. The Barcelona Basic Model (BBM) is a constitutive model to describe the geomechanical behaviors of partially saturated soils. Complicated tests are required to directly measure BBM parameters of bentonite. In this study, we demonstrate that probable BBM parameters can be sought by calibrating the BBM parameters to match simulation results to observed ones for two kinds of simple tests (swelling pressure test and free swelling test) instead of the complicated direct tests. In the swelling pressure test and free swelling test that were conducted by Japan Atomic Energy Agency (JAEA), water was injected into constrained and unconstrained bentonite core samples, and then swelling pressure and displacements were measured, respectively. We find optimal BBM parameters using a quasi-Newton optimization method that reproduce the observed swelling pressures and displacements in hydro-mechanical simulations. The optimal BBM parameters that are sought in the inversion process can be used to predict the THM behaviors of bentonite barriers in a high-level radioactive waste disposal system.

The Korea Atomic Energy Research Institute is developing a nuclide management process that separates high heat, high mobility, and long half-life nuclides that burden the disposal of spent fuel, and disposes of spent fuel by nuclide according to the characteristics of each nuclide. Various offgases (volatile and semi-volatile nuclides) generated in this process must be discharged to the atmosphere below the emission standard, so an off-gas trapping system is required. In this study, we introduce the analysis results of the parameters that affect the design of the off-gas trapping system. The analyzed contents are as follows. The physical quantities of the Cs, Tc/se, and I trapping filters according to the amount of spent nuclear fuel, the maximum exothermic temperature of the Cs trapping filter and the absorbed dose by distance by Cs radioactivity were analyzed according to the amount of spent nuclear fuel. In addition, a three-dimensional CFD (Computational Fluid Dynamics) analysis was performed according to operating parameters by simply modeling the off-gas trapping system, which is easy to modify mechanical design parameters. It is considered that the analysis results will greatly contribute to the development of the off-gas trapping system design requirements.

The buffer is a critical barrier component in an engineered barrier system, and its purpose is to prevent potential radionuclides from leaking out from a damaged canister by filling the void in the repository. No experimental parameters exist that can describe the buffer expansion phenomenon when Kyeongju bentonite, which is a buffer candidate material available in Korea, is exposed to groundwater. As conventional experiments to determine these parameters are time consuming and complicated, simple swelling pressure tests, numerical modeling, and machine learning are used in this study to obtain the parameters required to establish a numerical model that can simulate swelling. Swelling tests conducted using Kyeongju bentonite are emulated using the COMSOL Multiphysics numerical analysis tool. Relationships between the swelling phenomenon and mechanical parameters are determined via an artificial neural network. Subsequently, by inputting the swelling tests results into the network, the values for the mechanical parameters of Kyeongju bentonite are obtained. Sensitivity analysis is performed to identify the influential parameters. Results of the numerical analysis based on the identified mechanical parameters are consistent with the experimental values.

9% nickel steel has remarkable mechanical properties in a cryogenic condition and is widely used in storage containers for LNG fueled ships. Demand for laser welding rather than conventional arc welding has grown to increase manufacturing efficiency. However there are various types of heat sources which are suggested by other researchers. With that, it is difficult to select a proper heat source shape for welding conditions. The author proposed a representative heat source model that can cover most of suggested heat source models through previous studies. Welding power was fixed at 4kW and the speed was changed to 1.0m/min, 1.5m/min, and 2.0m/min respectively. The shapes of the welding heat sources were derived, and the tendency of the main parameters was also deducted. It was observed that the width and depth of the weld bead decreased as the welding speed increased through welding experiment, parameters of welding heat source are changed linearly. Based on this study, it is expected that it will be possible to estimate the shape of the heat source under untested welding conditions.

본 연구의 목적은 우리나라 Jersey 암소 56두로부터 조사된 체고 데이터에 대해 성장 모형을 추정하고, 추정된 체고 성장 모형의 모수를 활용하여 우리나라 Jersey 암소의 체고 성장 기초 자료를 제공하고자 실시하였다. 추정된 Gompertz, von Bertalanffy, Logistic 및 Brody 모형의 체고 성장 곡선 함수식은 각각      ,         ,          및       이었다. 추정된 Gompertz, von Bertalanffy 및 Logistic 모형의 모수를 이용하여 성장 특성을 분석한 결과 변곡점 월령이 각각 -0.3880, -5.235 및 -0.426월로 성장 기간 중 존재하지 않았다. Gompertz, von Bertalanffy, Logistic 및 Brody 모형에 대한 오차 평균 제곱합은 각각 14.189, 14.083, 14.730 및 14.011로 추정되었으며, 모형 결정 계수는 각각 0.971, 0.972, 0.970 및 0.972로 추정되었 다. 각 모형의 오차 평균 제곱합과 모형 결정 계수의 결과를 종합해보면 Brody 모형이 Jersey 암소의 체고 성장 곡선에 적합도가 좋은 것으로 판단된다.

Background: Although several studies have reported functional improvements after forward walking training on a treadmill and after backward walking training on a treadmill, there is a lack of immediate effects data, investigating spatiotemporal parameter, neuromuscular recruitment. Objectives: To compare the immediate effects between forward and backward walking on treadmill training, present study measured muscle activities of the lower extremity, gait parameters, and dynamic balance. Design: Cross-sectional study. Methods: The twenty-four asymptomatic young male subjects were participated in this study. Subjects have performed 15-min of forward and backward walking on treadmill. Before and after treadmill walking, the gait parameters were measured with the GAITRite. The dynamic balance abilities were assessed with the Y-balance test. Muscular activities were collected from the tibialis anterior, gastrocnemius, biceps femoris, and rectus femoris during forward and backward walking. Results: Muscular activities of the biceps femoris and tibialis anterior were significantly different between forward and backward walking conditions, which were higher with the backward walking (P<.05). Compared to the pre-measurement, the normalized dynamic balance composite score of the post-measurement was significantly higher with the backward walking (P<.05). Regardless of the treadmill training method, there were no significant differences between pre and post measurement, both the stride length and step length (P>.05). Conclusion: The performing backward walking training has positive effects for dynamic balance.

본 연구는 고속스핀에코 기법을 이용한 MRI 검사에서 영상 변수가 전자파 흡수율(SAR)과 온도 증가에 미치는 영향을 평가해 보고자 하였다. 이를 위해 인체 등가 조직 팬텀을 제작하였고 같은 조건에서 재위상화 RF의 FA와 ETL을 증가시키 며 MRI 검사를 시행하였다. SAR는 장비에서 계산된 두부 SAR값을 사용하였고 팬텀의 온도 변화는 양성자 공명 주파수를 이용해 계산하였다. 실험 결과, FA를 60°에서 180°까지 증가시켰을 때 SAR는 약 8배까지 상승하였고 팬텀의 온도 상승의 폭은 약 2.8배(0.21°-0.599°) 증가하였다. 그리고 다중 회귀 분석 결과, FA는 SAR와 온도 상승의 관계에서 표준화 계수 가 각각 0.935, 0.741로 나타나 높은 상관관계를 보였다. ETL은 15에서 30까지 증가시켰을 때 SAR는 약 2배 증가하였 다. 하지만 팬텀의 온도 상승 폭은 오히려 39.2%(0.53°-0.303°) 감소하였다. 다중 회귀 분석 결과에서도 ETL은 SAR의 관계에서 표준화 계수가 0.741로 양의 상관관계를 보였지만 온도 상승의 경우 표준화 계수가 –0.482로 나타나 음의 상관 관계가 있었다. 이는 ETL이 15에서 30까지 증가함에 따라 검사 시간이 약 43% 짧아져 전자파의 노출 시간이 감소한 것이 원인이 될 수 있다. 결국, FSE 기법을 이용한 MRI 검사에서는 재위상화 FA는 최소화하고 기준 SAR 범위 내에서 ETL을 최대로 적용하면 전자파로 인한 온도 상승을 최소화할 수 있어 환자 안전을 증진 시킬 수 있을 것으로 기대한다.

본 연구는 환경측정용 센서 위치에 따른 온실 환경의 공간· 수직적 특성을 조사하고 온실 종류에 따른 온도, 광도 및 CO2 농도 간의 상관관계를 구명하고자 수행하였다. 벤로형 온실의 공간적인 5지점을 선정한 후 각 지점에서 대표적 작물의 수 직적 높이 4지점과 지면부, 지붕 공간에 온도, 상대습도, CO2, 엽온 및 광센서를 설치하였다. 벤로형 온실과 반밀폐형 온실 에서 온도, 광도 및 CO2 농도 변화의 관계성을 Curve Expert Professional 프로그램을 이용하여 비교하였다. 벤로형 온실 의 공간적 위치에 따른 편차는 CO2 농도가 다른 요인보다 큰 것으로 나타났다. CO2 농도는 평균 465－761μmol·mol-1 범 위였고, 편차가 가장 큰 시간대는 오후 5시였으며, 최고 농도 는 액화 탄산가스 공급장치의 메인 배관(50∅)과 가까운 위치 인 중앙 후부(Middle End, 4ME)에서 646μmol·mol-1, 최저 농도는 좌측 중앙(Left Middle, 5LM)에서 436μmol·mol-1이 었다. 수직적 위치에 따른 편차는 온도와 상대습도가 다른 요 인보다 큰 것으로 나타났다. 평균 기온의 편차가 가장 큰 시간 대는 오후 2시대이며, 최고 기온은 작물 위 공기층(Upper Air, UA)에서 26.51℃, 최저 기온은 작물의 하단부(Lower Canopy, LC)에서 25.62℃였다. 평균 상대습도의 편차가 가장 큰 시간 대는 오후 1시대로 나타났으며, 최고 습도는 LC에서 76.90%, 최저 습도는 UA에서 71.74%이다. 각 시간대에 평균 CO2 농 도가 가장 높은 수직적 위치는 지붕 공간 공기층(Roof Air, RF)과 시설 내 지면(Ground, GD)이었다. 온실 내 온도, 광도 및 CO2 농도의 관계성은 반밀폐형 온실의 경우 결정계수(r2) 가 0.07, 벤로형 온실은 0.66이었다. 결과를 종합하여 볼 때, 온실 내 CO2 농도는 공간적 분포, 온도와 습도는 작물의 수직 적 분포 차이를 측정하여 분석할 필요가 있고 환기율이 낮은 반밀폐형 온실의 경우 목표 CO2 시비 농도가 일반 온실과 다 르게 설정해야 할 것으로 판단된다.

본 연구는 우리나라 Jersey 암소 41두로부터 측정된 체중 데이터를 이용해 Gompertz, von Bertalanffy 및 Logistic 모형의 성장 곡선을 추정하고, 추정된 성장 곡선의 모수를 활용하여 Jersey 암소의 성장 특성에 대해 알아보고자 실시하였다. 추정된 Gompertz, von Bertalanffy 및 Logistic 모형의 성장 곡선 함수식은 각각    ,         및          이었다. Gompertz, von Bertalanffy 및 Logistic 모형에 대해 변곡점은 각각 10.719, 8.4292 및 14.618 개월로 추정되었고, 변곡점 체중은 각각 208.514, 211.347 및 203.548kg으로 추정되었으며, 최대 증체율은 각각 20.851, 21.192 및 21.993 (kg/월)로 추정되었다. 오차 평균 제곱합과 모형 결정 계수의 결과를 종합해보면 von Bertalanffy, Gompertz 그리고 Logistic 모형 순으로 Jersey 암소 성장 곡선에 적합도가 높은 것으로 판단된다.

Various models have been proposed to describe the swelling behavior of buffer in high level waster repository. One of the most notable models, the Barcelona Basic Model (BBM), is a mechanical model that simulates the behavior of unsaturated ground and is widely applied to soils that undergo large expansion due to water. Among the BBM parameters of Kyeongju bentonite, which is found in Korea, there are no experimental data for parameters that describe the unsaturated state. Such hydromechanical properties should be characterized through experimental programs. However, such experiments are highly complicated and require long periods of time to produce an unsaturated state through different methods according to the suction range. Although there are several studies in which geotechnical parameters were obtained through a back analysis instead of direct experiments, few studies have employed machine learning methods for the identification of geotechnical parameters. In this study, instead of direct experiments, the results of a relatively simple swelling pressure experiment was compared to the numerical analysis results to propose a method of determining some of BBM parameters. Influential factors were identified by a sensitivity analysis and the values of the factors were estimated using an artificial neural network and optimization method. The obtained parameters were applied to the numerical model to estimate the swelling pressure growth, which was subsequently compared to the experimental value. As a result, it was found that there was no significant difference between the two swelling values.

Seismic demand on nonstructural components (NSCs) is highly dependent on the coupled behavior of a combined supporting structure- NSC system. Because of the inherent complexities of the problem, many of the affecting factors are inevitably neglected or simplified based on engineering judgments in current seismic design codes. However, a systematic analysis of the key affecting factors should establish reasonable seismic design provisions for NSCs. In this study, an idealized 2-DOF model simulating the coupled structure-NSC system was constructed to analyze the parameters that affect the response of NSCs comprehensively. The analyses were conducted to evaluate the effects of structure-NSC mass ratio, structure, and NSC nonlinearities on the peak component acceleration. Also, the appropriateness of component ductility factor (R p) given by current codes was discussed based on the required ductility capacity of NSCs. It was observed that the responses of NSCs on the coupled system were significantly affected by the mass ratio, resulting in lower accelerations than the floor spectrum-based response, which neglected the interaction effects. Also, the component amplification factor (a p) in current provisions tended to underestimate the dynamic amplification of NSCs with a mass ratio of less than 15%. The nonlinearity of NSCs decreased the component responses. In some cases, the code-specified R p caused nonlinear deformation far beyond the ductility capacity of NSCs, and a practically unacceptable level of ductility was required for short-period NSCs to achieve the assigned amount of response reduction.

본 연구는 우리나라 Holstein의 번식형질에 대한 유전모수를 추정하기 위하여, 2009년부터 2013년까지 분만한 농협 젖소개량사업소의 검정자료 경산우 144,793두의 211,899개의 번식기록을 이용하였다. 7가지 형질의 유전 및 오차 (공)분산을 WOMBAT 패키지를 이용하여 분석하였다. CTFS, GL, NRR, NS, FSTC, DO 및 CI의 유전력은 각각 0.064, 0.060, 0.005, 0.014, 0.012, 0.021 및 0.021로 추정되었다. 형질들 간의 유전상관은 –0.910에서 0.995로 나타났다. NRR과 NS, NRR과 FSTC 간에는 부의 유전상관이 나타났으나, DC와 CI는 강한 양의 유전상관을 나타냈다. CTFS와 FSTC는 DO 및 CI와 유의하게 양의 유전상관관계를 나타냈다(0.479~0.862). CTFS와 FSTC 사이의 낮은 유전상관은 두 형질이 서로 다른 유전적 측면에 있다는 것을 의미한다. 본 연구는 번식능력 개량을 위한 기초 자료를 제공할 수 있을 것이라 판단한다.

This study was conducted to identify and assess key parameters affecting greenhouse gas emissions and odor intensity at a naturally ventilated dairy farm. Measurement data of greenhouse gases (CO2, CH4, N2O), odorants (NH3 and H2S), and meteorological data (wind speed, temperature, relative humidity, and solar radiation) were posited as the parameters influencing those emissions. Carbon dioxide and methane emissions correlated well to CO2-equivalent emissions and the contribution of carbon dioxide emissions (R2=0.9181) was greater than that of methane emissions (R2=0.8854). Hydrogen sulfide emissions were highly correlated with odor intensity (R2=0.9989), but the contribution of ammonia emissions to odor intensity was not significant (R2=0.0081). No correlation among CO2-equivalent and odor intensity emissions and meteorological parameters was observed. In this study, the relationship between emissions of greenhouse gases and odor intensity in a naturally ventilated dairy barn mainly depended upon carbon dioxide and hydrogen sulfide emissions. The results in this study will be helpful in the mitigation planning of greenhouse gases and odor in animal feeding operations (CFOs).

The carbon-based nanostructures are in limelight due to their widespread applications in nano-to-micro-scale technologies. The carbon dots are known for their unique physical, electrical, optical, chemical and biological properties. The carbon dots (CDs) are being produced through several well-developed synthesis methods, one of which is the green sonochemical. This method is preferred over others because it is a green source of energy, facile, fast, low-temperature process, non-toxic and less expensive. Despite the fact of using 90% less energy than other methods, this method has been overlooked in the published literature. It is possible to prepare pure and doped CDs of low toxicity and controlled physicochemical properties through sonochemical method. In recent years, sonochemically produced CDs have been tuned and characterized for a variety of applications. This review has explored the merits and demerits of sonochemical method in comparison to the other methods for the synthesis of pure CDs and their nanocomposites. The role of multiple factors in tailoring the specific parameters of CDs for their application in antibacterial, polymerization, tissue engineering, catalysis, bio-imagining, supercapacitors, drug delivery and electric devices is also elaborated in this review. This review also concludes on future directions in the applications of sonochemically produced CDs.

Because sows are industrially vital for swine production, monitoring for their health or disorder status is important to ensure high reproductive performance. Especially, ambient temperature changes in different season, especially during summer, are directly influenced to the reproductive performance of sows. Although the serum biochemical parameters are widely applied in the veterinary medicine with wide ranges for the physiological process, the values are also influenced by several factors such as age, breed, gender, and stress. In addition, domestic sows in Koreaspecific reference interval (RI) for serum biochemistry has not been established yet. Therefore, the present study was aimed to evaluate seasonal variation of RIs in the serum biochemistry in domestic sows in Korea at different seasons and to establish normal RIs using a RI finding program (Reference Value Advisor). Significant difference (p < 0.05) on the different seasons were identified in several serum biochemical parameters including BUN, CRE, GGT, GLU, ALB, TP, LDH and Na in sows. Therefore, we further established RIs, specific in domestic sows in Korea regardless of season. The established RIs based on the serum biochemical values provide a baseline for interpreting biochemical results in the domestic sows in Korea, regardless of seasonal effect. It may contribute to develop a strategy for better reproductive performance by improving breeding management practice and evaluating health of pig herds, which facilitate to avert the economic loss in summer infertility in sows.