• Bulletin of the Korean Chemical Society
• /
• v.12 no.6
• /
• pp.692-698
• /
• 1991

The reaction path Smoluchowski equation approach developed in a recent work to calculate the rate constant for a diffusive multidimensional barrier crossing process is extended to incorporate the configuration-dependent diffusion matrix. The resulting formalism is then applied to the investigation of stilbene photoisomerization dynamics. Adapting a model two-dimensional potential and a model diffusion matrix proposed by Agmon and Kosloff [J. Phys. Chem.,91 (1987) 1988], we derive an eigenvalue equlation for the relaxation rate constant of the stilbene photoisomerization. This eigenvalue equation is solved numerically by using the finite element method. The advantages and limitations of the present method are discussed.

• Journal of Environmental Science International
• /
• v.25 no.7
• /
• pp.951-961
• /
• 2016

To prevent increasing instances of heat-related illnesses due to heat waves generated by climate change, a customized thermal environment index should be developed for outdoor workers. In this study, we conducted sensitivity analysis of the Masan harbor during a heat wave period (August 9th to 15th, 2013) using the MENEX model with metabolic rate and clothing-insulation data, in order to obtain realistic information about the thermal environment. This study shows that accurate input data are essential to gather information for thermophysiological indices (PST, DhR, and OhR). PST is sensitive to clothing insulation as a function of clothing. OhR is more sensitive to clothing insulation during the day and to the metabolic rate at night. From these results, it appears that when exposed to high-temperature thermal environments in summer, wearing highly insulated clothing and getting enough rest (to lower the metabolic rate) can aid in preventing heat-related illnesses. Moreover, in the case of high-intensity harbor work, quantification of allowed working time (OhR) during heat waves is significant for human health sciences.

• KSTLE International Journal
• /
• v.3 no.1
• /
• pp.49-53
• /
• 2002

Inconel 690 for nuclear steam generator tube has more chromium than the conventionally used Inconel 600 in order to increase the corrosion resistance. TD evaluate the tribological characteristics under fretting condition the fretting tests as well as sliding tests were carried out in elevated temperature water environment. Fretting tests of the cross-cylinder type were done under various vibrating amplitudes and applied normal loads in order to measure the friction forces and wear volumes. Also, the conventional sliding tests of pin-en-disk type were carried out to compare the test results. In fretting, the friction was very sensitive to the load and the amplitude. The friction coefficient decreased with increasing load and decreasing amplitude. Also, the wear of Inconel 690 can be predictable using the work rate model. Depending on normal loads and vibrating amplitudes, distinctively different wear mechanisms and of ten drastically different wear rates can occur. It was fecund that the fretting wear coefficients in water were increased as increasing the temperature of water.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.10a
• /
• pp.191-194
• /
• 2003

The results from a systematic study of the response of a Ti-6Al-4V alloy under quasi-static and dynamic loading at different strain rates and temperatures are presented. It has been shown that the work-hardening rate decreased as the strain rate and the strain increased. The correlations and predictions using modified KHL (Khan-Huang-Liang) viscoplastic constitutive model are compared with those from JC (Johnson-Cook) model and experimental observations. Overall, KHL model correlations and predictions compared much more favorably than the corresponding JC model predictions and correlations.

• Nuclear Engineering and Technology
• /
• v.55 no.8
• /
• pp.3071-3079
• /
• 2023

Helium production in the nuclear fuel matrix during irradiation plays a critical role in the design and performance of Gen-IV reactor fuel, as it represents a life-limiting factor for the operation of fuel pins. In this work, a surrogate model for the helium production rate in fast reactor MOX fuels is developed, targeting its inclusion in engineering tools such as fuel performance codes. This surrogate model is based on synthetic datasets obtained via the SCIANTIX burnup module. Such datasets are generated using Latin hypercube sampling to cover the range of input parameters (e.g., fuel initial composition, fission rate density, and irradiation time) and exploiting the low computation requirement of the burnup module itself. The surrogate model is verified against the SCIANTIX burnup module results for helium production with satisfactory performance.

• Journal of Biosystems Engineering
• /
• v.42 no.2
• /
• pp.98-103
• /
• 2017

Purpose: Precision agriculture includes determining the right amount of nitrogen for a specific location in the field. This work focused on developing and validating a model using variable rate nitrogen application based on the estimated SPAD value from the ground-based image sensor. Methods: A variable rate N application based on the decision making system was performed using a sensor-based variable rate nitrogen application system. To validate the nitrogen application decision making system based on the SPAD values, the developed N recommendation was compared with another conventional N recommendation. Results: Sensor-based variable rate nitrogen application was performed. The nitrogen deficiency level was measured using the image sensor system. Then, a variable rate application was run using the decision model and real-ti me control. Conclusions: These results would be useful for nitrogen management of corn in the field. The developed nitrogen application decision making system worked well, when considering the SPAD value estimation.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.36 no.3
• /
• pp.135-145
• /
• 2020

Recently, the disaster rate of the construction industry has increased with high-rise, and complexity of the building, unlike the decrease in the disaster rate in other industries. Although risk assessment is performed to reduce the occurrence of disasters, it is difficult to estimate the risks accurately due to activity in which no disaster has occurred, and inconsistencies in the level of details of work. In this study, in order to evaluate the risk of the major activity for the apartment construction work, the activity was identified by referring to the risk assessment model of construction industry type by the KOSHA. The construction work types and activities were consistently organized in level of work into nine work types and 82 activities were through experts consultation. Analyzing the disaster types that occurred during work through KOSHA disaster cases, calculating the probability of disaster occurrence according to the type of disaster, and combining the probability of disaster with the severity of disaster to estimate the risk assessment method was presented. Using the daily report of the construction site of the apartment, the results of a case study confirmed the validity of the risk calculation method presented in this study.

• Journal of Biomedical Engineering Research
• /
• v.36 no.5
• /
• pp.198-203
• /
• 2015

The purpose of the study is to examine the effects of pacemaker location on cardiac pumping efficacy theoretically. We used a three-dimensional finite element cardiac electromechanical model of canine ventricles with models of the circulatory system. Electrical activation time for normal sinus rhythm and artificial pacing in apex, left ventricular free wall, and right ventricular free wall were obtained from electrophysiological model. We applied the electrical activation time maps to the mechanical contraction model and obtained cardiac mechanical responses such as myocardial contractile ATP consumption, stroke work, stroke volume, ejection fraction, and etc. Among three artificial pacing methods, left ventricle pacing showed best performance in ventricular pumping efficacy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.12
• /
• pp.11-20
• /
• 2011

PSALI is referred to the supplementary lighting for the interior lighting under the daily lighting situation, and pursuant to the pertinent regulations in energy savings design standard and others in recent architecture works, the importance thereof has been increasing gradually coupled with the energy performance index (EPI), energy savings plan and the like as well as expansion of submittal and implementation policies. However, this type of PSALI studies indeed have a number of limitations since it has surrounding environmental conditions in direction, season, region, climate, time, opening rate, window area ratio, actual index, reflection rate of finishing materials and others in the architecture work as well as frequent changes in interior lighting environment for variables in daily light volume flowing into the interior, and others. Therefore, this study has analyzed existing advance research cases to produce the actual-sized model and scaled-down model, and installed the artificial lighting of LED light source possible to reproduce with same capability on both models. As a result of comparison and analysis of the artificial lighting with the key light, it has certain level of error rate from the scaled down lighting device in certain rate and actual model butit was noticeably significant within specific scope.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.31 no.4
• /
• pp.353-366
• /
• 2021

Objectives: An appropriate level of cost support is being proposed to maximize the participation rate. In addition, as the amount of support is highly concentrated at the level of the limit under the current level of supports, the level of cost support is low when the actual level of cost of measuring the working environment exceeds the limit. This paper describes the adjustment of an appropriate cost support rate. Methods: First, this paper analyzes the current cost support status using data from the KOSHA. Second, an alternative for adjusting the cost support rate is presented in consideration of the incentive aspect. Third, we present simulation results for the average cost support rate, the impact of each alternative on finance, and more. Fourth, the most desirable adjustment method is presented after comparing and analyzing the results of various alternatives. Results: In this paper, we present a new scale model. This model is a mixture of flat-rate, fixed rate, and subside cap. It is expected that the new model will not only facilitate participation in businesses with low measurement costs, but also have the effect of controlling measurement costs for institutions that incur greater costs. It is also expected that setting a cap will have the effect of considering government finances and inducing excessively costly institutions to reduce costs. Thus, the new model is likely to be superior to others. If the fourth plan is applied to new businesses and the fifth plan is applied to sustainable businesses, the average cost support rates will be 87.68 percent and 65.18 percent, respectively, and the needed finances will be 2.5 billion won, 18.8 billion won, and 21.3 billion won in total. Conclusions: It seems most desirable to introduce a new model that combines flat-rate, fixed-rate, and subsidy cap systems and achieve an appropriate cost support rate through this model.