• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.434-440
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• 2007

The Effluent ground water overflows in deep and broad ground space building. Temperature of effluent ground water is in 12$\sim$18$^{\circ}C$ annually and the quality of that water is as good as living water. Therefore if the flow rate of effluent ground water is sufficient as source of heat pump, that is good heat source and heat sink of heat pump. Effuent ground water contain the thermal energy of surrounding ground. So this is a new application of ground source heat pump. In this study open type and close type heat pump system using effluent ground water was installed and tested for a church building with large and deep ground space. The effluent flow rate of this building is 800$\sim$1000 ton/day. The heat pump capacity is 5RT each. The heat pump system heating COP was 3.0$\sim$3.3 for the open type and 3.3$\sim$3.8 for the close type system. The heat pump system cooling COP is 3.2$\sim$4.5 for the open type and 3.8$\sim$4.2 for close type system. This performance is up to that of BHE type ground source heat pump.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.490-500
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• 2000

A new technique for the source location of acoustic emission (AE) in plates whose thichness are close to or thinner than the wavelength has been studied by introducing wavelet transform de-noising technique. The detected AE signals were pre-processed using wavelet transform to be decomposed into the low-frequency, high-amplitude flexural components and the high-frequency, low-amplitude extensional components. If the wavelet transform de-noising was employed, we could successfully filter out the extensional wave component, one of the critical errors of source location in plates by arrival time difference method. The accuracy of source location appeared to be significantly improved and independent of the setting of gain and threshold, plate thickness, sensor-to-sensor distance, and the relative position of source to sensors. Since the method utilizes the flexural component of relatively high amplitude, it could be applied to very large, thin-walled structures in practice.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.257-270
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• 2022

This paper analyzes the effect of profit incentives within the setting of bounty open source project. A simple decision-making model based on classical utility maximization is presented for open source developers that includes income effects from the bounty prize. We then simulate the decisions of multiple developers to assess the effect from the bounty prize. Our result shows that learning costs can greatly reduce the software quality improvement benefit from bounty project. It also suggests that open source projects can benefit more when they have multiple small bounty projects than a single large bounty project since it reduces the learning cost and the opportunity cost for the open source developers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.10
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• pp.974-983
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• 2014

The commercialization of ITS(Intelligent Transport System) is in sight including V2V(Vehicle-toVehicle) communication and analysis of related electromagnetic circumstances is essential process in relevant legislation. However analysis including numbers of vehicles have electrically large environment which leads to a lack of computational resources. In this letter, we suggest superposition method which require much less computational resources by subgrouping environment and using post-processing of results. Suggested method approximate original result by superpositioning of analysis which include scatterers near source, observation point. This letter also presented guideline of method and example for comparison with full analysis result.

• Atmosphere
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• v.24 no.3
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• pp.317-329
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• 2014

Eddy covariance data have been analyzed to investigate the influence of surface heterogeneity on turbulent transfer over farmland and industrial sites near Nakdong river, Korea, where both large and small scale heterogeneities co-exist. For this purpose, basic turbulent statistics, quadrant analysis and multi-resolution decomposition have been analyzed during the daytime. Basic turbulent statistics were compared with typical turbulent statistics in the surface layer. Such comparisons were in close agreement for momentum and heat at both sites but not for water vapor at industrial site. The correlation coefficient between water vapor and vertical velocity ($r_{wq}$) is relatively low and skewness of water vapor ($sk_q$) is very low at industrial site, possibly due to limited water source. For heat at both sites and water vapor at farmland, the quadrant analysis show similar behavior to that over homogeneous site but for water vapor at industrial site, the presence of river and limited water source at industrial site seems to influence on water vapor transfer by coherent eddy motion by increasing sweep contribution and decreasing ejection contribution. Multi-resolution decomposition analysis shows that large scale heterogeneity leads to low $r_{Tq}$ at large averaging time regardless of season at both sites and there are seasonal changes of $r_{Tq}$ in mid-averaging times at industrial site, possibly due to seasonal change of trees and grasses near the site.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.9
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• pp.1205-1212
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• 2010

The aim of the present study was to evaluate the effects of replacing 70% of the protein from fish meal by protein from ensiled or dry cassava leaves and sweet potato vines on the performance and carcass characters of growing F1 (Large White${\times}$Mong Cai) pigs in Central Vietnam. Twenty-five crossbred pigs (Large White${\times}$Mong Cai) with an initial weight of 19.7 kg (SD = 0.84) were allocated randomly to five treatment groups with 5 animals per group (3 males and 2 females). Pigs were kept individually in pens ($2.0{\times}0.8\;m$) and fed one of five diets over 90 days. The control diet was formulated with fish meal (FM) as the protein source while the other four diets were formulated by replacing 70% of fish meal protein by protein from ensiled cassava leaves (ECL), dry cassava leaves (DCL), dry sweet potato vines (DSPV) or ensiled sweet potato vines (ESPV). Animals were fed their diets at 4% of BW. Results showed that final BW, ADG, DMI and feed conversion ratio (FCR) among the experimental treatments were not significantly different (p>0.05). ECL or DCL and ESPV reduced feed cost per unit gain by 8-17.5% compared to the fish meal diet. There were no significant differences in carcass characters among the diets (p>0.05). Lean meat percentages and protein deposition ranged 41.5-45.8% and 40.2-52.9 g/d, respectively. Using ensiled or dry cassava leaves and sweet potato vine can replace at least 70% of the protein from fish meal (or 35% of total diet CP) without significant effects on performance and carcass traits of growing (20-65 kg) pigs. Including cassava leaves and sweet potato vines could improve feed cost and therefore has economic benefits.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.621-629
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• 2007

This study intends to investigate the characteristics of the foul smell of sewer pipes near large apartment complexes as complaints about offensive odors have drastically increased in urban residential areas. Targeting apartments where people actually complained about foul orders, the study result revealed that components in the smell of the water-purifier tank of the target apartment were very similar to those of sewage treatment plants and night soil treatment plants. Measuring components of odors inside the management layer of tank showed that the concentration of hydrogen sulfide was 10ppm, which is approximately 160 times the safety standard of 0.06ppm; the concentration of mercaptan was 0.9ppm, which is about 220 times the safety standard of 0.004ppm. The source materials of foul odors were discharged outside through ducts, and those households living near outlets producing bad smell complain that it gets worse depending on the air pressure or wind direction and strength, and they could not even open windows. As well, these source materials were transferred by discharge pumps to public sewer pipes outside the apartment complex. While discharge pumps starts operating, they remain on the sewer pipe and then begin to spread over to roads through small openings of manholes on the road. Then, the smell offends passers-by and residents near the road, leading to a lot of complaints. The study results suggest that, among the sources of foul odors in sewer pipes of residential areas, especially those from the water-purifier tank of large apartments, hydrogen sulfide should be the main target for follow-up treatment.

• Nuclear Engineering and Technology
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• v.50 no.5
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• pp.627-638
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• 2018

This article describes an integrated Level 1-Level 2 probabilistic risk assessment (PRA) methodology to evaluate the radiological risk during postulated accident scenarios initiated during the decommissioning phase of a typical Mark I containment boiling water reactor. The fuel damage scenarios include those initiated while the reactor is permanently shut down, defueled, and the spent fuel is located into the spent fuel storage pool. This article focuses on the integrated Level 1-Level 2 PRA aspects of the analysis, from the beginning of the accident to the radiological release into the environment. The integrated Level 1-Level 2 decommissioning PRA uses event trees and fault trees that assess the accident progression until and after fuel damage. Detailed deterministic severe accident analyses are performed to support the fault tree/event tree development and to provide source term information for the various pieces of the Level 1-Level 2 model. Source terms information is collected from accidents occurring in both the reactor pressure vessel and the spent fuel pool, including simultaneous accidents. The Level 1-Level 2 PRA model evaluates the temporal and physical changes in plant conditions including consideration of major uncertainties. The goal of this article is to provide a methodology framework to perform a decommissioning Probabilistic Risk Assessment (PRA), and an application to a real case study is provided to show the use of the methodology. Results will be derived from the integrated Level 1-Level 2 decommissioning PSA event tree in terms of fuel damage frequency, large release frequency, and large early release frequency, including uncertainties.

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.51-54
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• 2021

The DC system has less power loss compared to the AC system because there is no influence of frequency and dielectric loss. However, the zero-crossing point of the current is not detected in the event of a short circuit fault, and it is difficult to interruption due to the large fault current that occurs during the opening, so the reliability of the DC breaker is required. As a solution to this, an LC resonance DC circuit breaker combined a superconducting element has been proposed. This is a method of limiting the fault current, which rises rapidly in case of a short circuit fault, with the quench resistance of the superconducting element, and interruption the fault current passing through the zero-crossing point through LC resonance. The superconducting current limiting element combined to the DC circuit breaker plays an important role in reducing the electrical burden of the circuit breaker. However, at the beginning of a short circuit fault, superconducting devices also have a large electrical burden due to large fault currents, which can destroy the element. In this paper, the reactor is connected to the source side of the circuit using PSCAD/EMTDC. After that, the change of the fault current according to the reactor capacity and the electrical burden of the superconducting element were confirmed through simulation. As a result, it was confirmed that the interruption time was delayed as the capacity of the reactor connected to the source side increased, but peak of the fault current decreased, the zero-crossing point generation time was shortened, and the electrical burden of the superconducting element decreased.

• Progress in Medical Physics
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• v.14 no.2
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• pp.81-89
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• 2003

The dose distributions of designed Ir-192 micro-source were investigated by dose computations which were accomplished by employing shape of encapsule material and thickness of the source for self-absorption. The computation dose derived from air-kerma rate (S$_{k}$ ) and dose rate constant (Λ) includes the anisotropy of dose distribution around the source. We got the dose rate constants in a water medium is 1.154 cGy h$^{-1}$ U$^{-1}$ . The size of the source was 0.5 mm in diameter and 3.5 mm in length and it was encapsuled in 1.1 mm$\Phi$${\times}$5.5 mm of stainless steel sealed with 0.3 mm of filter thickness. The tissue dose of reference point at 1.0 cm radial distance of the source axis was delivered 1.154 Uh$^{-1}$ (1.3167${\times}$10$^{-3}$ cGy/mCi-sec) from the S$_{k}$ 4.108U/mCi of Ir-192 source. The filtration effect contributed to air-kerma strength as exponential filtering effect of 86.2% in total attenuation, but self-absorption was 88.4% from radial dose distributions. In particular, the dose attenuations showed a rapid anisotropic distributions as 56% of reference dose along to $\pm$10 degrees from the tip of source axis and 50% for of that to source-cable direction. We persist in use the large diameter of applicator will avoid the dose anisotropy by the filtered attenuation effects along the axis of Ir-192 micro-source.