• Korean Journal of Organic Agriculture
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• v.17 no.3
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• pp.307-326
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• 2009

The present study suggests a concept of resources circulation type agriculture and a concept of a livestock zone related to it and evaluated economical efficiency about a possibility of the resources circulation type livestock zone based on the concept. As a result, when the resources circulation type livestock zone is operated in an area of 1,300ha, it was evaluated that the profit of 11,244 hundred thousand won per year is generated, compared to the conventional agriculture. When light and heat expenses and roughage of Hanwoo production, production of TMR forage as well as income of the energy and composting business of livestock manure at the recycling center were considered in addition to that, it was judged that the present zone development bushiness has enough business feasibility. However, it is necessary that the support regulations, etc. is constructed so that all produced compost byproducts are used at farmhouses and the system related to facility investment assurance and assistance of operating expenses is maintained. It is thought that the complement of a system is also necessary so that energy or power generation expenses can be operated in the same conditions as other new & renewable energy, and the nation's purchase of carbon credits(CDM) is investigated and systemized in the early period, and construction of a revitalization plan of the business through budget securing of the Ministry of Agriculture and Forestry related to the trade of CDM and carbon emission rights is also a business that should be urgently developed. In the future, the change of an outside environment will further promote use of the energy. Also, as people, who don't know agriculture. farm village, increase day by day because of population concentration in a city, an opportunity that can new added value through experience tourism or educational programs utilizing them is increasing. Accordingly, if programs utilizing social characteristics, such as utilization as a space of tourism. leisure. experience, system construction of bio-energy and system construction that Micro Grid or Smart Grid as a dispersed storage and generation system is stabilized, are constructed, it can be said that revitalization or success conditions of the zone is further achieved.

• Nuclear Engineering and Technology
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• v.40 no.1
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• pp.21-36
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• 2008

High bum-up fuel technology has been developed through a national R&D program, which covers key technology areas such as claddings, $UO_2$ pellets, spacer grids, performance code, and fuel assembly tests. New cladding alloys were developed through alloy designs, tube fabrication, out-of-pile test and in-reactor test. The new Zr-Nb tubes are found to be much better in their corrosion resistance and creep strength than the Zircaloy-4 tube, owing to an optimized composition and heat treatment of the new Zr-Nb alloys. A new fabrication technology for large grain $UO_2$ pellets was developed using various uranium oxide seeds and a micro-doping of Al. The uranium oxide seeds, which were added to $UO_2$ powder, were prepared by oxidizing and heat-treating scrap $UO_2$ pellets. A $UO_2$ pellet containing tungsten channels was fabricated for a thermal conductivity enhancement. For the fuel performance analysis, new high burnup models were developed and implemented in a code. This code was verified by an international database and our own database. The developed spacer grid has two features of contoured contact spring and hybrid mixing vanes. Mechanical and hydraulic tests showed that the spacer grid is superior in its rodsupporting, wear resistance and CHF performance. Finally, fuel assembly test technology was also developed. Facilities for mechanical and thermal hydraulic tests were constructed and are now in operation. Several achievements are to be utilized soon by the Korea Nuclear Fuel and thereby contribute to the economy and safety of PWR fuel in Korea

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.2
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• pp.100-104
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• 2023

Autogenous bone grafts from the mandibular ramus are a known source of inadequate bone volume scenarios of the residual alveolar ridge. However, the conventional block-type harvesting technique cannot prevent bone marrow invasion, which can cause postoperative complications such as pain, swelling, and inferior alveolar nerve injury. This study aims to suggest a complication-free harvesting technique and present the results of bone grafting and donor sites. One patient received two dental implants with a complication-free harvesting technique that involves creation of ditching holes with a 1 mm round bur. Sagittal, coronal, and axial osteotomies produced grid-type cortical squares using a micro-saw and a round bur to confirm the cortical thickness. The grid-type cortical bone was harvested from the occlusal aspect, and the harvesting was extended through an additional osteotomy on the exposed and remaining cortical bone to prevent bone marrow invasion. The patient did not suffer postoperative severe pain, swelling, or numbness. After 15 months, the harvested site exhibited new cortical bone lining, and the grafted area had healed to a cortico-cancellous complex with functional loading of the implants. Our technique, grid-type cortical bone harvesting without bone marrow invasion, allowed application of autogenous bone without bone marrow invasion to achieve acceptable bone healing of the dental implants and to regenerate the harvested cortical bone.

• New & Renewable Energy
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• v.8 no.1
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• pp.18-23
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• 2012

The screen printing has been widely used to form silver electrodes in solar cell device due to their simplicity of process. However, the wavy and irregular surface which is believed to be originated from a screen mask mesh and thixotropic characteristics of paste on screen printing process is well-known to give a negative effect on solar cell efficiency. The dispensing method that the silver paste is extruded through micro nozzle under a moderate pressure and coated on substrate can form the silver electrode without any wavy surface. In this study, we optimize the composition of silver paste and develop paste blending condition based on the thixotropic behavior of paste. The optimized paste shows a large thixotropic loop area which is related to an aspect ratio of electrode line and has the viscosity of 40 $Pa{\cdot}s$ at 40 s-1. The electrode line we finally obtainis 67.2 ${\mu}m$ in width and has an aspect ratio of 0.277.

• Textile Coloration and Finishing
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• v.32 no.4
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• pp.239-244
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• 2020

Polyethylene (PE) micro-fiber have been prepared at different hot air temperature (60, 80 and 100 ℃) and different pressure (20, 40, 60 and 80 kPa) by melt centrifugal spinning technique. The parameters of melting centrifugal spinning including polymer contents, rotational velocity, temperature of hot air and pressure were optimized for the fabrication process. The study showed that 8000 rpm rotational velocity, 80 ℃ heated hot air and 40 kPa air pressure are the best condition to obtain uniform and strong PE fiber. The prepared PE fibers were analyzed by field emission scanning electron microscope and universal testing machine and found that fibers with reduced diameter and improved tensile strength are obtained at hot air condition.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1254-1266
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• 2024

This study investigates the application of supercritical carbon dioxide (S-CO₂) direct-cycle micro modular reactors (MMRs) in primary frequency control (PFC), which is a scenario characterized by significant load fluctuations that has received less attention compared to secondary load-following. Using a modified GAMMA + code and a deep neural network-based turbomachinery off-design model, the authors conducted an analysis to assess the behavior of the reactor core and fluid system under different PFC scenarios. The results indicate that the acceptable range for sudden relative electricity output (REO) fluctuations is approximately 20%p which aligns with the performance of combined-cycle gas turbines (CCGTs) and open-cycle gas turbines (OCGTs). In S-CO₂ direct-cycle MMRs, the control of the core operates passively within the operational range by managing coolant density through inventory control. However, when PFC exceeds 35%p, system control failure is observed, suggesting the need for improved control strategies. These findings affirm the potential of S-CO₂ direct-cycle MMRs in PFC operations, representing an advancement in the management of grid fluctuations while ensuring reliable and carbon-free power generation.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.59-65
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• 2011

According to the trends of electronic package to be smaller, thinner and more integrative, Flip Chip Ball Grid Array (FCBGA) become more used for mobile phone. However, the flip chip necessarily generate the heat by the electrical resistance and generated heat is increased due to reduced distribution area of the heat in accordance with the miniaturization trend of the package. Thermal issues can result in problems of devices that are sensitive to temperature and stress. Then the heat can generate problems to the system. In this paper, in order to improve the thermal issues of FCBGA, thermal characteristics of FCBGA was analyzed qualitatively by using the general heat transfer module of Comsol 3.5a and In order to solve thermal issues, flip chip with new micro structure is proposed by the simulation. and also by comparing existing model and analyzing variables such as pitch, height of the pattern and shape of the heat spreader, the improvement of heat dissipation characteristics about 18% was confirmed.

• Journal of Ecology and Environment
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• v.43 no.2
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• pp.226-245
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• 2019

To understand the dynamics of radial growth of trees and micro-climate at a site of Korean fir (Abies koreana Wilson) forest on high-altitude area of Mt. Hallasan National Park, Jeju Island, Korea, high precision dendrometers were installed on the stems of Korean fir trees, and the sensors for measuring micro-climate of the forest at 10 minutes interval were also installed at the forest. Data from the sensors were sent to nodes, collected to a gateway wireless, and transmitted to a data server using mobile phone communication system. By analyzing the radial growth data for the trees during the growing season in 2016, we can estimate that the radial growth of Korean fir trees initiated in late April to early May and ceased in late August to early September, which indicates that period for the radial growth was about 4 months in 2016. It is interesting to observe that the daily ambient temperature and the daily soil temperature at the depth of 20 cm coincided with the values of about 10 ℃ when the radial growth of the trees initiated in 2016. When the radial growth ceased, the values of the ambient temperature went down below about 15 ℃ and 16 ℃, respectively. While the ambient temperature and the soil temperature are evaluated to be the good indicators for the initiation and the cessation of radial growth, it becomes clear that radii of tree stems showed diurnal growth patterns affected by diurnal change of ambient temperature. In addition, the wetting and drying of the surface of the tree stems affected by precipitation became the additional factors that affect the expansion and shrinkage of the tree stems at the forest site. While it is interesting to note that the interrelationships among the micro-climatic factors at the forest site were well explained through this study, it should be recognized that the precision monitoring made possible with the application of high resolution sensors in the measurement of the radial increment combined with the observation of 10 minutes interval with aids of information and communication technology in the ecosystem observation.

• Korean Journal of Materials Research
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• v.14 no.3
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• pp.186-190
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• 2004

An electron beam microcolumn composed of an electron emitter, micro lenses, scan deflector, and focus lenses have been fabricated and tested in the STEM mode. In this paper, we report a technique of precisely aligning the electron lenses by the laser diffraction patterns instead of the conventional alignment method based on aligner and STM. STEM images of a standard Cu-grid were observed using a fabricated microcolumn under both the retarding and accelerating modes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.140-140
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• 2009

The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEM-type FCs system was integrated by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with variations on mass flow rate and stack temperature. The ranges of the variations are $20{\sim}70^{\circ}C$ on stack temperature and 1~8L/min on $H_2$ volume.