• The KSFM Journal of Fluid Machinery
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• v.5 no.1 s.14
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• pp.49-54
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• 2002

HANARO, 30 MW of research reactor, was installed at the depth of 13m in an open pool. The $90\%$ of primary coolant was designed to pass through the core and to remove the reaction heat of the cote. The rest, $10\%$, of the primary coolant was designed to bypass the core. And the reactor coolant through and bypass the core was inhaled at the top of chimney by the coolant pump to prevent the radiated gas from being lifted to the top of reactor pool. But, the part of core bypass coolant was not inhaled by the reactor coolant pump and reached at the top of reactor pool by natural convection, and increased the radiation lovel on the top of reactor pool. To reduce the radiation level by protecting the natural convection of the core bypass flow, the hot water layer (HWL, hereinafter) was installed with the depth of 1.2 m from the top of reactor pool. As the HWL was normally operated, the radiation level was reduced to five percent ($5\%$) in comparing with that before the installation of the HWL. When HANARO was operated at a higher temperature than the normal temperature of the HWL by operating the standby heater, it was found that the radiation level was more reduced than that before operation. To verify the reason, the heat loss of the HWL was calculated by Visual Basic Program. It was confirmed through the results that the larger the temperature difference between the HWL and reactor hall was, the more the evaporation loss increased. And it was verified that the radiation level above was reduced mote safely by increasing the capacity of heater.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.221-226
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• 2001

HANARO, 30MW of research reactor, was installed at the depth of 13m of open pool, The $90\%$ of primary coolant was designed to pass through the core and to remove the reaction heat of the core. The rest $10\%$, of the primary coolant was designed to bypass the core. And the reactor coolant through and bypass the core was inhaled at the top of chimney by the coolant pump to protect that the radiated gas was lifted to the top of reactor pool. But, the part of core bypass coolant was not inhaled by the reactor coolant pump and reached at the top of reactor pool by natural convection and increased the radiation level on the top of reactor pool. To reduce the radiation level by protecting the natural convection of the core bypass flow, the hot water layer (HWL, hereinafter) was installed with the depth of 1.2m from the top of reactor pool. As the HWL was normally operated, the radiation level was reduced to five percent ($5\%$) in comparing with that before the installation of the HWL. When HANARO was operated with higher temperature than the normal temperature of the HWL by operating the standby heater, it was found that the radiation level was more reduced than that before operation. To verify the reason, the heat loss of the HWL was calculated. It was confirmed through the results that the larger the temperature difference between the HWL and reactor hall was, the more the evaporation loss was increased. And it was verified that the radiation level above was reduced more safely by increasing the capacity of heater.

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.138-143
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• 1999

Recently, miniaturization of large scale integrated circuits (LSI) and printed circuit board (PCB) have become essential with the downsizing of electronic devices. Gold electroplating is applied of conductivity wiring or terminals for improvement of conductivity and corrosion resistance. However, electroplating is not applicable since the circuits are becoming finer and denser. Accordingly, electroless plating is recently highly attractive method because of the simplicity of the operation requiring no external source of current and no elaborate equipment. In this work, we tried to develop a plating technique on electroless Ni/Au plating. First, the electroless Ni plating was deposited on the PCB with agitation in the bath at $85^{\circ}C$. Then the Au layer was deposited on the Ni layer surface by same method at $90^{\circ}C$. The bonderability were tested in order to evaluate the stability of the electroless Ni/Au by gold wire or solder ball test.

• The Journal of Society for e-Business Studies
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• v.25 no.1
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• pp.109-121
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• 2020

The purpose of this study is to find out primary policies for reducing PM(particulate matter) as well as for improving the quality of life. Serious particulate matters cause to diverse healthcare and economy problems including business transactions. Unfortunately, until recently there are very few researches regarding the decision-making process for particulate matter policies. This study has applied the AHP(Analytic Hierarchy Process) method to develop cooperative policy making processes. The upper layer of this hierarchy analysis consists of four parts, i.e., transportation, production facility, living environment, and urban planning management. And each upper layer parts has their own three policies. 25 experts including policy-makers, academic researchers and industrial specialists have decided the primary policies and directions. The most significant PM policy is the mandatory reduction of air pollution and suspension of factory operation in the production industry. The results of this study can lead to guidelines for making environmental policies.

• Journal of the Korean Magnetics Society
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• v.12 no.2
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• pp.64-67
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• 2002

IrMn pinned spin valve (SV) films with stacks of Ta/NiFe/IrMn/CoFe/Cu/CoFe/NiFe/Ta were prepared by dc sputtering onto thermally oxidized Si (111) substrates at room temperature under a magnetic field of about 100 Oe. The annealing cycle number and temperature dependence of exchange coupling field (H$_{ex}$), magnetoresistance (MR) ratio, and coercivity (H$_{c}$) were investigated. By optimizing the process of deposition and post thermal annealing condition, we obtained the IrMn based SV films with MR ratio of 3.6%, H$_{ex}$ of 1180 Oe for the pinned layer. The H$_{ex}$ is stabilized after the second annealing cycle and it is thought that this SV reveals high thermal stability. The H$_{ex}$ maintained its strength of 600 Oe in operation up to 24$0^{\circ}C$ and decreased monotonically to zero at 27$0^{\circ}C$.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1303-1308
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• 2007

Recently, precast concrete tracks are replacing ballast track for efficient and economic maintenance of track. Precast concrete railroad tracks are manufactured in factory, and transported to railroad construction site for installation. Therefore, quality of precast concrete track itself should be sufficiently good. On the contrary to the convenient manufacturing of precast concrete track, the installation of a precast concrete track requires careful steps. Typically, a precast concrete track is placed on an approximately 15-cm thick lean concrete layer. A mortar is filled between lean concrete layer and precast concrete track to adjust the sloping angle of a precast concrete track for a safe train operation at a curvy section. Then, the use of filled mortarproduces a void underneath a precast concrete track, which is harmful to structural safety of a precast concrete track undercyclic loading. Therefore, it is essential to make sure that there is no void left beneath a precast concrete track after mortar filling. In the continuous resonance method, the amplitude of frequency response measured using an instrumented hammer and an accelerometer is plotted against a pseudo-depth, which is half of the wave velocity divided by frequency. The frequency response functions are measured at consecutive measurement locations, 6-cm interval between measurement points, and then combined together to generate a 2-D plot of frequency response. The sections with strong reflections or large amplitude of frequency response are suspicious areas with internal voids and unfilled areas. The 2-D frequency response plot was efficient in locating problematic sections just by examining the color shade of a visualized plot in 2-D format. Some of the problematic sections were drilled to make a visual inspection of mortar filling. The visual image of interface between mortar and precast concrete track was verified using the validity of the continuous resonance technique adopted in this research.

• Archives of Plastic Surgery
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• v.33 no.4
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• pp.495-498
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• 2006

Purpose: Trichoblastic fibroma originates from hair germ layer tumor which is a benign tumor mixture of epidermal and mesodermal factor. Trichoblastic fibroma was found only in adults and showed equal occurrence rate between men and women. Since it is a rare tumor, we report a case of a trichoblastic fibroma which developed on the right cheek. Methods: A 72 year-old male was treated with excisional operation 17 years ago due to a solitary tumor that developed on the same site. He returned to the hospital with an asymptomatic mass which have been increasing in size for the last 3 months. Results: In computerized tomography, a size of $2.7{\times}2.3{\times}0.8cm$ tumor was found in the subcutaneous tissue layer. Grossly, the mass was well-circumscribed, smooth-surfaced and flesh colored, and was lobulated and fragile. Pathologic observation showed diverse shaped and sized tumor cell nests and fibrocellular stroma consisting basophilic cells in dermal and subdermal layers. Immunohistopathologic staining showed positive reaction on pancytokeratin, CK-5/6, and bcl-2. Conclusion: By having no connection to the epidermis, and being positioned in the dermal and epidermal layers, typical pathologic findings make it possible to differentiate this tumor with basal cell carcinoma. This lesion is not clear whether it is a local recurrence or not, and it is necessary to observe a new recurrence in the future.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1361-1370
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• 2006

Recently fast innovation of Internet technology causes lot of application to change into web application and requirement for the inter-operable communication among various systems are increased rapidly. These trends are part of changes which is caused by ubiquitous world and it is just beginning of huge waves that is required to fit and change under the ubiquitous environments. This thesis is focused on the Design and Implementation of Layer Structured Components which can be interfaced effectively for the Material Management System under the Heterogeneous Client Server Environments. The key points to do that kinds of affairs are using XML web services that can communicate thru systems and also using independent layered components for the enforcement of reusability and inter-operability. For the various type of testing of implementation, we used RFID System, PDA, Desktop Systems and confirmed the normal operation without concerning the type of client system and platforms. The Components proposed in this thesis could be reused effectively in case of developing similar applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.329-332
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• 2012

LEDs are using widely in a field of illumination, LCD LED backlight, mobile signals because they have several merits, such as low power consumption, long lifetime, high brightness, fast response, environment friendly. To achieve high performance LEDs, one needs to enhance output power, reduce operation voltage, and improve device reliability. In this paper, we have proposed that the optimum design and specialized process could improve the performance of LED chip. It was showed an output power of 7cd and input supplied voltage of 3.2V by the insertion technique of current blocking layer. In this paper, GaN-based LED chip which is built on the sapphire epi-wafer by selective MOCVD were designed and developed. After that, their performances were measured. It showed the output power of 7cd more than conventional GaN-based chip. It will be used the lighting source of a medical equipment and LCD LED TV with GaN-based LED chip.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.417-421
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• 2009

Purpose: Dermatofibrosarcoma protuberans(DFSP) is a moderate - degree malignant tumor of soft tissue from dermis to fat layer with high recurrences(11% to 73%) due to its local infiltrative characteristic. Many debates and controversies in deciding accurate surgical margin were presented before, but references about depth of invasion and appropriate surgical excision level were not properly made out. Therefore, we tried to identify the degree of tissue invasion of DFSP. Methods: Twenty patients, including 8 patients with recurrent lesions, over last 10 years were reviewed retrospectively. Different surgical margins were applied according to the location and based on histopathologic result, we have defined as a 'deep tissue invasion' if there were infiltration of tumor cell into fascia or underlying muscle layer was present. All invaded tissue including dermis, fat, fascia and muscle were excised until no tumor cell was found during intraoperative frozen section biopsy. And comparative analysis of deep tissue invasion according to age, primary site, duration of disease and recurrence was done. Results: Thirteen patients(65%) showed deep tissue invasion and incidence was found to be increasing with age(over 30 years old). All patients with DFSP on head and neck region revealed deep tissue invasion followed by trunk(54%) and lower extremities(50%). There was no relationship between duration of disease and deep tissue invasion. Conclusions: It is clear that many cases of DFSP had a deep tissue invasion. And high prevalence of deep tissue invasion with age, primary site was intimately associated. So, underlying deep tissue must be completely examined and excised sufficiently throughout the operation for clear resection of DFSP with no recurrences, especially when age is over 30s and on head and neck region.