• Macromolecular Research
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• v.12 no.2
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• pp.172-177
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• 2004

We have studied the lamella-level morphology of poly(ethylene terephthalate) (PET)/polycarbonate (PC) blends using small-angle X-ray scattering (SAXS). Measurements were made as a function of the holding time in the melt. We determined the morphological parameters at the lamellar level by correlation function analysis of the SAXS data. An increased amorphous layer thickness was identified in the blend, indicating that some PC was incorporated into the interlamellar regions of PET during crystallization. The blend also exhibits a larger lamella crystalline thickness (l$\sub$c/) than that of pure PET. A possible reason for the increase in l$\sub$c/ is that the inclusion of the PC molecules in the interlamellar regions causes an increase in the surface free energy of folding. At the early stage of isothermal crystallization, we observed a rapid drop in the value of l$\sub$c/ in the blend; this finding indicates that a relatively large fraction of secondary crystals form during the primary crystallization. In contrast, the value of l$\sub$c/ for the sample that underwent a prolonged holding time increased with time in the secondary crystallization-dominant regime; this observation suggests that the disruption of chain periodicity, which results from transesterification between the two polymers, favors the development of fringed micellar crystals that have larger values of l$\sub$c/ rather than the development of normal chain-folded crystals.

• Composites Research
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• v.18 no.6
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• pp.1-8
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• 2005

The fiber-reinforced composite materials have been advanced for various applications because of their excellent mechanical and electromagnetic properties. On their manufacturing processes, however, thermo-curing inherently produces the undesired thermal deformation mainly from temperature drop from the process temperature to the room temperature, so called spring-back. The spring-back must be understood especially in the hybrid composites in order to design and fabricate desired shape. In this research, (glass fiber / epoxy) + (carbon fiber / epoxy) unsymmetric hybrid composites were fabricated under various conditions such as cure cycle, laminate thickness, stacking sequence and curing sequence. Coupons were made and spring-back were measured using coordinate measuring machine (CMM). Using the Classical Lamination Theory (CLT) and finite element analysis (ANSYS), the behavior of spring-back were predicted and compared with the experimental data. The results from CLT and FEA agreed well with the experimental data. Although, the spring-back could be reduced by lowering curing temperature, at any case, the spring-back could not be removed completely.

• International Commerce and Information Review
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• v.13 no.3
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• pp.301-323
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• 2011

There have been 20 cases of trade disputes related to zeroing in WTO. In these day, it was judged that the use of zeroing in the calculation of dumping margin is against ADA. Recently, WTO decided in favor of Korea in regards to Korea's stainless steel products on January, 2011. There finally was a high possibility of zeroing being changed. In December 2010, the American government announced it would revise zeroing system through an federal register. Many researchers, such as Linsey and Ikenson(2000), William W. Nye(2009) already clarified through empirical analysis that no use of zeroing leads to a large decline in the margin of dumping. If zeroing is abolished in the future, the margin of dumping imposed on Korea's stainless steel will drop sharply. According to this empirical study, the margin of dumping in 6 stainless steel among 12 products commodities subject to Anti Dumping regulation from US reduced below de-minimis or 3%. These stainless steel is likely to be excluded from the Anti Dumping regulation through review investigation and Korea's export of steel to America is expected to be increased steeply in the future.

• Korean Journal of Microbiology
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• v.39 no.1
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• pp.51-55
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• 2003

To develop environment-friendly biofertilizer solubilizing insoluble phosphates, a bacterium possessing a high ability to solubilize $Ca_{3}(PO_{4})_{2}$) was isolated from the rhizosphere of peas. On the basis of its morphological, cultural, physiological characteristics, and Vitek analysis, this bacterium was identified as Pantoea agglomerans. The optimal medium composition and cultural conditions for the solubilization of insoluble phosphate by P. agglomerans R-38 were 3% of glucose.0.1% of TEX>$NH_{4}NO_{3}$, 0.02% of $MgSO_{4}\cdot\7H_{2}O$, and 0.06% of $CaCl_{2}\cdot\2H_{2}O$ along with initial pH 7.5 at $30^{\circ}C$. The highest soluble phosphate production under optimum condition was 898 mg/L after 5 days of cultivation. The solubilization of insoluble phosphate was associated with a drop in the pH of the culture medium. The strain produced soluble phosphate to the culture broth with the concentrations of 698 mg/L against CaHPO$_4$, 912 mg/L against hydroxyapatite, 28 mg/L against $FePO_{4}\cdot\4H_{2}O$, and 19 mg/L against $AIPO_{4}$, respectively.

• Korean Institute of Interior Design Journal
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• v.19 no.6
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• pp.233-240
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• 2010

This research is designed to study the residence environment of the elderly residing in three different types of residence - the local community, silver towns and nursing homes and compare their level of social support and life satisfaction of the residents. The subjects of the study was those aged 65 and older who live single and couple 68 residing in the local community, 32 in silver town and 32 in nursing homes. The result of analysis is as follows; 1) the residence environment is different in the three types of residence in terms of number of children, living with a spouse, subjective economic status, and participation in group activities; 2) as for social support, emotional support is the highest among the elderly residing in the local community and declines among those in silver town and the lowest in nursing homes, which suggests that the local community still maintain the support system for the elderly, however it declines in silver town and drop further in nursing homes. But in terms of instrumental support, there is no meaningful difference in the three types of residence. The result shows that the elderly residing in nursing homes are supported by systematic medical and residence service which make up for instrumental support Similar to those in the local community and silver town; 3) life satisfaction is the highest among those residing in nursing homes, however there was little meaningful difference. The result means quality of living is similar among three different types of residence. What is interesting is those living in nursing homes has similar level of life satisfaction despite their lowest emotional support.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.7
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• pp.592-601
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• 2018

The GPS/INS integrated navigation system, which is one of the electronic equipments mounted on military aircraft store, can not directly receive GPS signals by the aircraft wing before the drop, so GPS navigation data is received from the aircraft and used for filter integration, afterwards, the integrated navigation is performed using the GPS information directly received through the antenna. In this case, it is possible to operate the mount in old aircraft without any modification of the aircraft when GPS data is transmitted using wireless. However, the delay occurs while the aircraft navigation data is transmitted to the integrated navigation filter of the aircraft store via wireless, which affects the time synchronization of the GPS measurement and the INS information, affecting the integrated navigation performance. In this paper, an algorithm to analyze and compensate the effect of generation and transmission delay that can occur when implementing GPS/INS integrated navigation system of aircraft store that receives GPS data via wireless.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.8
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• pp.687-693
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• 2018

In this paper, we studied on the thermal design of the active antenna system for stable performance considering thermal reliability. The active antenna has high performance and heat flux elements in T/R modules. Thermal heating of elements in T/R modules has to be dissipated effectively and the antenna has to be operated over the range of suggested temperature by the thermal design. T/R modules of high heat flux in the active antenna can be dissipated effectively by liquid cooling. In this study, we studied on the thermal design including the liquid cooling system to optimize the thermal performance of the active antenna. And the thermal design was verified by numerical analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.9
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• pp.681-689
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• 2020

This paper presents methods and results of both flight test examining roll angle estimation performance of slowly rolling munition forced to spin in the air, and fabricating a replica of guided munition. Guided munition was deployed from multi rotor type UAV mother ship whose altitude and velocity was conveyed to it as initial state. Flight test scenario is composed of a sequence of munition drop(deployment), munition spin, roll angle estimation and stabilization. Munition was deployed from mother ship at around 200m high with horizontal velocity of 15m/s, and was made spun using internal reaction wheel. Performance analysis on roll angle estimation is provided in comparison with commercial aerospace graded GPS/INS. Moreover, several mechanisms that rotates munition using reaction wheel, and actual product that realizes one of them are introduced.

• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.181-191
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• 2014

Modern commercial greenhouse requires the use of advanced climate control system to improve crop production and to reduce energy consumption. As an alternative to classical sensor-based control method, this paper introduces a model-based control method that consists of two models: the predictive model and the evaluation model. As a first step, this paper presents straightforward models to predict the effect of natural ventilation in a greenhouse according to meteorological factors, such as outdoor air temperature, soil temperature, solar radiation and mean wind speed, and structural factor, opening rate of roof ventilators. A multiple regression analysis was conducted to develop the predictive models on the basis of data obtained by computational fluid dynamics (CFD) simulations. The output of the models are air temperature drops due to ventilation at 9 sub-volumes in the greenhouse and individual volumetric ventilation rate through 6 roof ventilators, and showed a good agreement with the CFD-computed results. The resulting predictive models have an advantage of ensuring quick and reasonable predictions and thereby can be used as a part of a real-time model-based control system for a naturally ventilated greenhouse to predict the implications of alternative control operation.

• Korean Institute of Interior Design Journal
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• v.26 no.5
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• pp.42-51
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• 2017

The purpose of this study was to analyze the information about the disaster temporary shelter space planning guidance described in the U.S. shelter guidelines in terms of the habitability for disaster victims and to address the implications and potential impacts of its findings for the improvement of the shelter design standards and guidelines in Korea. The researchers reviewed four federal and non-governmental organization shelter field and design guidelines and attributes regarding the shelter space planning were classified in accordance with four habitability categories: Safety, Health, Convenience, and Comfort. Three major findings emerged from this study: 1)A total of 72 items about the shelter space planning were extracted from guidelines, and the majority of items are concerned with dormitory areas and sanitary spaces. Other items were about accessibility, children respite care area, signage, health service areas, food preparation and serving areas, parking and drop-off areas, registration and waiting areas, shelter manager and staff areas, lounge and storage areas, and household pets area. 2)Most of these items are strongly related to the convenience category(66.7%), followed by comfort(40.3%), safety(30.6%), and health(25.0%). 3)The habitability of the disaster temporary shelter can be established with considerations on the needs of disaster victims and vulnerable people, minimum occupancy space per person, separate sanitary spaces for the privacy, safe and convenient access routes to the shelter, and the provision of children areas for safety and comfort. The study findings will contribute to the development of the disaster shelter guidelines in Korea by suggesting shelter space planning indicators related to the habitability for the governmental and non-governmental organizations' immediate and systematic responses to the disaster.