• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.1
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• pp.13-21
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• 2011

To characterize the site specific properties of a study area for high-level radioactive waste disposal research in KAERI, the several geological investigations such as surface geological surveys and borehole drillings were carried out since 1997. Especially, KURT (KAERI Underground Research Tunnel) was constructed to understand the further study of geological environments in 2006. As a result, the first geological model of a study area was constructed by using the results of geological investigation. The objective of this research is to construct a hydrogeological model around KURT area on the basis of the geological model. Hydrogeological data which were obtained from in-situ hydraulic tests in the 9 boreholes were estimated to accomplish the objective. And, the hydrogeological properties of the 4 geological elements in the geological model, which were the subsurface weathering zone, the log angle fracture zone, the fracture zones and the bedrock were suggested. The hydrogeological model suggested in this study will be used as input parameters to carry out the groundwater flow modeling as a next step of the site characterization around KURT area.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.9 no.3
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• pp.191-198
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• 2011

In general, conventional criticality analyses for spent fuel transport/dry storage systems have been performed based on assumption of fresh fuel concerning the potential uncertainties from number density calculation of Transuranic and Fission Products in spent fuel. However, because of economic loss due to the excessive criticality margin, recently the design of transport/dry storage systems with Burnup Credit(BUC) application has been actively developed. The uncertainties in criticality analyses on transport/storage systems with BUC technique show strong dependance upon initial enrichment and burnup rate, whereas those in the conventional criticality evaluation based on fresh fuel assumption do not show such a dependance. In this study, regulatory-required uncertainties of the criticality analyses for BK 26 Cask, which is conceptually designed spent fuel transport cask with BUC corresponding to the limiting circumstances on nuclear power plants in Korea, are evaluated as a function of initial enrichment and burnup rate. Results of this study will be used as basic data for spent fuel loading curve of BK 26 Cask.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.151-159
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• 2017

A deep geological disposal at a depth of 500 m in stable host rock is considered to be the safest method with current technologies for disposal of spent fuels classified as high-level radioactive waste. The most important requirement is that the temperature of the bentonite buffer, which is a component of the engineered barrier, should not exceed $100^{\circ}C$. In Korea, the amount of spent fuel generated by nuclear power generation, which accounts for about 30% of the total electricity, is continuously increasing and accumulating. Accordingly, the area required to dispose of it is also increasing. In this study, various duplex disposal concepts were derived for the purpose of improving the disposal efficiency by reducing the disposal area. Based on these concepts, thermal analyses were carried out to confirm whether the critical disposal system requirements were met, and the thermal stability of the disposal system was evaluated by analyzing the results. The results showed that upward 75 m or downward 75 m apart from the reference disposal system location of 500 m depth would qualify for the double layered disposal concept. The results of this study can be applied to the establishment of spent fuel management policy and the design of practical commercial disposal system. Detailed analyses with data of a real disposal site are necessary.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.135-149
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• 2017

Demonstration programs for spent nuclear fuel dry storage have been carried out to produce important and confirmatory data to support safety of dry storage systems and integrity of spent nuclear fuel stored in dry condition. The US initiated the dry storage of spent nuclear fuel and has strict and explicit regulatory stipulations on the integrity of spent nuclear fuel in dry storage. The US has carried out several notable demonstration programs for the initiation and license extension of dry storage. At the very early stage of dry storage, the demonstration programs were focused on proof of the safety of dry storage systems and a demonstration project called the dry cask storage characterization project was performed for the license extension of low burn-up fuel dry storage. Currently, a demonstration program for the license extension of high burn-up fuel dry storage is under way and is expected to continue for at least 10 years. Korea has not yet begun the dry storage of PWR fuel and the US programs can be a good reference and can provide lessons to safely begin and operate dry storage in Korea. In this paper, past and current demonstration programs of the US are analyzed and several recommendations are provided for demonstration programs for the dry storage of spent nuclear fuel in Korea.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.176-187
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• 1997

As a way to evaluate the performance of IGCC (Integrated Gasification Combined Cycle) processes, heating values of coal gas as well as plant efficiency were compared for different rank coals and coal feeding methods by employing the static process simulation technique. Performance of the process was compared with coal rank that was varied by three assorted bituminous coals and also by three subbituminous coals, in addition to the two types of feeding techniques, i.e., dry-feeding and slurry-feeding, that are utilized in entrained-bed coal gasifiers. For the verification of the simulation technique, simulated results were compared first with the actual pilot plant data published from Shell and Texaco. The simulation technique was, then, applied to other coals. Result from tests varying coal rank exhibits the trend of improving both heating content of the product gas and plant efficiency with increasing carbon content in coal. The effect of coal rank is more sensitive in slurry-feeding cases compared to the dry-feeding cases. In particular, considering notably lower values in gas heating value and plant efficiency calculated in the slurry-feeding case that uses a subbituminous coal, limited utilization of the slurry-feeding method for subbituminous coals can be expected. From the plant efficiency point of view, dry-feeding method resulted in higher simulated efficiency values by maximum 3% for subbituminous coals and ca. l% for bituminous coals.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.99-120
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• 2017

In SS branch of Korea District Heating Corporation, Combined Heat & Power power plant with 99MW capacity and 98Gcal / h capacity is operated as a district electricity business. In this region, it is difficult to operate the generator due to the problem of surplus heat treatment between June and September due to the economic recession and the decrease in demand, so it is urgent to develop an economical energy new business model. In this study, we will develop an optimized operation model by introducing a renewable energy hybrid system based on actual operation data of this site. In particular, among renewable energy sources, fuel cell (Fuel Cell) power generation which can generate heat and electricity at the same time with limited location constraints, photovoltaic power generation which is representative renewable energy, ESS (Energy Storage System). HOMER (Hybrid Optimization of Multiple Energy Resources) program was used to select the optimal model. As a result of the economic analysis, 99MW CHP combined cycle power generation is the most economical in terms of net present cost (NPC), but 99MW CHP in terms of carbon emission trading and renewable energy certificate And 5MW fuel cells, and 521kW of solar power to supply electricity and heat than the supply of electricity and heat by 99MW CHP cogeneration power, it was shown that it is economically up to 247.5 billion won. we confirmed the results of the improvement of the zone electricity business condition by introducing the fuel cell and the renewable energy hybrid system as the optimization process model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.2
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• pp.16-23
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• 2006

This paper presents a novel single-stage high frequency resonant inverter link type DC-DC converter using zero voltage switching with high power-factor. The proposed topology is integrated half-bridge boost rectifier as power factor corrector(PFC) and half-bridge high frequency resonant converter into a single-stage. The input stage of the half-bridge boost rectifier works in discontinuous conduction mode(DCM) with constant duty cycle and variable switching frequency. So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. Simulation results have demonstrated the feasibility of the proposed high frequency resonant converter. Characteristics values based on characteristics analysis through circuit analysis is given as basis data in design procedure. Also, experimental results are presented to verify theoretical discussion. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, fluorescent lamp and DC-DC converter etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.272-279
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• 2018

This study was conducted to compare the muscle strength, muscle power, and H/Q ratio according to energy system contribution in athletes participating in various sports. Subjects of the study were assigned into an Anaerobic Exercise Group (AEG, n=60; Short-Distance, Weight Lifting, Jumping, Throwing, Bowling, Golf) and an Endurance Exercise Group (EEG, n=60; Modern Pentathlon, Field Hockey, Handball, Cycle, Boxing, Rowing) groups. Isokinetic peak torque/body weight% and flexor/extensor ratio at 60, 180 deg/sec of knee extension and flexion were measured using an cybex 770. Data analysis was conducted using an independent t-test and one-way ANOVA. Based on the results of this study, there was higher extension, flexion strength and flexion power in the AEG than the EEG (p<0.05). We also confirmed higher muscle strength and muscle power in short distance and jumping athletes than other athletes participating in other events (p<0.05). However, there was no significant difference within the endurance exercise group. The HS ratio was within a stable range of 50% to 60% in all events. Collectively, the outcomes of this study indicate that routine physiological and performance testing can provide measurable benefits for elite athletes and their coaches.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.22-29
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• 2004

An international project, known as Argo, for collecting data on temperature, salinity and velocity of currents in the world's oceans, has been started in the year 2000 and the full Argo array of approximately 3000 floats will be deployed by 2006. 18 countries deployed 1,023 floats, which are operating in the ocean of the world as of December 2003. In the present study, we tried to predict float distribution and a rate of drifting ashore of the floats after their termination based upon a product of the ocean general circulation model of JAMSTEC (Japan Marine Science and Technology Center). We first evaluated reliability of the model prodilct quantitatively by comparing trajectories of surface buoys of WOCE Surface Velocity Program (SVP) and those predicted by the model surface current field. It is found that the model is acceptable for practical application to deploy floats and to estimate those trajectories. 653 particles at 3-degree spacing are used to investigate the ratio of floats drifted ashore, given that during the first 4 years floats cycle between the surface and 2000m for 10 days and then floats are on just the surface for 100 years. The simulation indicates that about 29% of deployed floats will be drifted ashore within 100-year.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.1
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• pp.1-10
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• 2015

In the safety assessment of the geological disposal system of the radioactive wastes, the abnormal scenarios, in which the system is impacted by the abnormal events, need to be considered in addition to the reference scenario. In this study, characterization and prediction of well intrusion as one of the abnormal events which will impact the disposal system were conducted probabilistically and statistically for the safety assessment. The domestic well development data were analyzed, and the prediction methodologies of the well intrusion were suggested with a computation example. From the results, the annual well development rate per unit area in Korea was about 0.8 well/yr/km² in the conservative point of view. Considering the area of the overall disposal system which is about 1.5 km², the annual well development rate within the disposal system could be 1.2 well/yr. That is, it could be expected that more than one well would be installed within the disposal system every year after the institutional management period. From the statistical analysis, the probabilistic distribution of the well depth followed the log-normal distribution with 3.0363 m of mean value and 1.1467 m of standard deviation. This study will be followed by the study about the impacts of the well intrusion on the geological disposal system, and the both studies will contribute to the increased reliability of safety assessment.