• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.328-334
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• 2012

This paper proposes a design technique of wide-band antenna for handy phone with 700 MHz LTE(Long Term Evolution) low frequency bandwidth. The proposed antenna based on the PIFA(Planar Inverted-F type Antenna) structure was designed and considered. In order to realize the wide bandwidth, a round structure which is able to control the electric path length of current and a branch line element which can be obtain the dual resonance characteristics were introduced in this design. As a result, It was realized about 95 MHz bandwidth in spite of very small space of $30{\times}34mm$ used for FR-4 substrate with relative permitivity of 4.4 at 700 MHz band. Measurement results of return loss, bandwidth and gain radiation pattern were agreed well with their calculation results.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.45-53
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• 2012

Recently, with achieved US$ 500 Billion international cumulative construction order, the Korean government presented overseas construction industry visions for international orders of US$ 100 Billion and entering the top five countries in global construction market. Also, Korean companies are developing strategies for expansion of international markets. However, ODA loan projects are low risk for the Korea Construction companies trying to advance their overseas business. This study provides data-based advice on securing competence for Korean construction companies entering the global market through the ODA loan projects. To analysis construction firm's competitiveness for ODA loan project, FGD was utilized and BSA model was applied to the valuable analysis. Competencies highly assessed were construction quality control, relationship building through high-level diplomatic activities, and project management. Competencies requiring urgent improvement were handling risks of local countries, financing projects, and developing know-how within participating companies.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.990-995
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• 2012

A piezoelectric ultrasonic bone surgical instrument, usually used to remove the tartar out of teeth or to cut the dentine of the tooth, is a recently popular instrument for dental treatment due to its several merits such as small size, low-electric power and precision control of surgical operation. It has typically two parts of a tip and vibration system which is also composed of head, piezoelectric elements and tail-mass. In order to improve the performance of the instrument, it is important to standardize the size of the vibration system without tip for high performance. In this study, a Finite Element Analysis (FEA) was utilized to optimize the structure of ultrasonic instrument in vibration system. Consequently, this study revealed that influence of several tips on property were minimized and it showed good property at the frequency range of 22~32 kHz.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.205-212
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• 2011

The potential factors for quality loss of cleaned fresh ginseng and technology to be associated with the improvement of marketability through pre-packaging fumigation were examined. Major microorganisms isolated from fresh ginseng included Botrytis cinerea, and Erwinia sp. Others such as Cylindrocarpon sp., Fusarium spp., Pennicilium spp., Bacillus spp. were also found at relatively low frequency. The bacterial density of vacuum packaged fresh ginseng rapidly increased during simulated marketing. Little correlation between bacterial growth and package swelling was found. In order to improve packaging method of fresh ginseng, pre-packaging treatment of 2-phenylethyl alcohol (PE, 100 uL/L, 4 hr) was examined. The fumigation treatment effectively inhibited the growth of bacteria density and also effective on keeping firmness of ginseng root, especially in cortical portion. The internal gas compositions of plastic container packaged for ginseng were approximately ranged between 6 to 8% $O_2$and 3 to 4% $CO_2$. The $O_2$ level of fumigation treatment was lower than control whereas $CO_2$ level was higher. The upsurge of ethylene evolution I day after simulated marketing was found only in fumigation treatment but it returned to ordinary level at day 2. The sucrose content of 2-PE treatment was significantly reduced at 5 days after simulated marketing but reducing sugars like glucose and fructose remained at higher level. The difference in sugar levels was reduced after 10 days of simulated marketing. The decay of fresh ginseng began at the lateral or fine root, which is weak to physical damage, in general. The epidermis was more damaged. Plastic container packaging with PE fumigation could be an alternative to vacuum packaging, which allows an aerobic environment and prevents anaerobic respiration. Further study of pre-package fumigation is required to improve technology of fresh ginseng marketing.

• Korean Journal of Community Nutrition
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• v.20 no.3
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• pp.208-219
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• 2015

Objectives: According to preceding studies, many people with mental disability have unbalanced dietary habits or excessive intake of calories. Most of them are overweight or obese due to lack of self-control for food consumption, swallowing with inadequate chewing and physical inactivity. Therefore, this study aimed to assess the nutritional intake, including carotenoid, in mentally disabled people and find out a possible solution for nutritional improvement. Methods: People with intellectual disability (N=28), emotional disability (N=44) participated in this study. The disorder grades were from I to III and ages were between 20 and 65 years. Assessments included anthropometry, daily intake of nutrients, including carotenoid, ROMA III questionnaire for assessing bowel movement. Results: The average BMI of intellectually disabled people and emotionally disabled people was in the range of overweight and obesity respectively ($23.7{\pm}6.3kg/m^2$, $25.8{\pm}4.1kg/m^2$). Overall, the frequencies of vegetable and dairy product intakes were lower in this population. When compared with Recommended Nutrient Intake (RNI) from Dietary Reference Intakes for Koreans 2010, the intakes of vitamin $B_1$, vitamin $B_2$ and calcium were insufficient in both groups. Also, lycopene intakes of carotenoid were low, compared with traditional Korean diet of the non-disabled people from the second year 2008 of the 4th National Health and Nutrition Survey. In addition, emotionally disabled people also had lower intake of cryptoxanthin. Conclusions: The mentally disabled people in this study showed lower intakes of vitamin $B_1$, vitamin $B_2$, calcium and carotenoids. Based on these findings, we recommend that it is important to encourage mentally disabled people to consume sufficient amounts of such nutrients in order to promote nutritional status.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.10
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• pp.4609-4614
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• 2016

Purpose: To evaluate the therapeutic effects of copper reduction on angiogenesis-related factors in patients with glioblastoma multiforme treated by gamma knife radiosurgery. Materials and Methods: In the present block randomized, placebo-controlled trial, fifty eligible patients with a diagnosis of glioblastoma multiforme who were candidates for gamma knife radiosurgery were randomly assigned into two groups to receive daily either 1gr penicillamine and a low copper diet or placebo for three months. The intervention started on the same day as gamma knife radiosurgery. Serum interleukin-6 (IL-6), tumor necrosis $factor-{\alpha}$ ($TNF-{\alpha}$), vascular endothelial growth factor (VEGF) and copper levels were measured at baseline and after the intervention. The serum copper level was used as the final index of compliance with the diet. In order to control probable side effects of intervention, laboratory tests were conducted at the beginning, middle and end of the study. Results: The patients had a mean age and Karnofsky Performance Scale of 43.7 years and 75 respectively. Mean serum copper levels were significantly reduced in intervention group. Mean survival time was 18.5 months in intervention group vs. 14.9 in placebo group. VEGF and IL-6 levels in the intervention group were also significantly reduced compared to the placebo group and $TNF-{\alpha}$ increased less. Conclusions: It seems that reducing the level of copper in the diet and dosing with penicillamine leads to decline of angiogenesis-related factors such as VEGF, IL-6 and $TNF-{\alpha}$. Approaches targeting angiogenesis may improve survival and can be used as a future therapeutic strategy.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.19-28
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• 2017

False data injection attacks have recently been introduced as one of important issues related to cyber-attacks on electric power grids. These attacks aim to compromise the readings of multiple power meters in order to mislead the operation and control centers. Recent studies have shown that if a malicious attacker has complete knowledge of the power grid topology and branch admittances, s/he can adjust the false data injection attack such that the attack remains undetected and successfully passes the bad data detection tests that are used in power system state estimation. In this paper, we investigate that a practical false data injection attack is essentially a cyber-attack with uncertain information due to the attackers lack of knowledge with respect to the power grid parameters because the attacker has limited physical access to electric facilities and limited resources to compromise meters. We mathematically formulated a method of identifying the most vulnerable locations to false data injection attack. Furthermore, we suggest minimum topology changes or phasor measurement units (PMUs) installation in the given power grids for mitigating such attacks and indicate a new security metrics that can compare different power grid topologies. The proposed metrics for performance is verified in standard IEEE 30-bus system. We show that the robustness of grids can be improved dramatically with minimum topology changes and low cost.

• Journal of Drive and Control
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• v.17 no.1
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• pp.21-26
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• 2020

The load characteristics of a piston pump holder due to the squeeze effect are influenced by the surface shape and gap thickness of the holder (cradle). Therefore, the pressure distribution and the load capacity of the piston pump holder due to the squeeze effect are studied by using the CFD software and the surface shape and gap thickness of the piston pump holder are considered. In order to verify the accuracy of numerical results, the load capacities of a circular plate holder are numerically studied, and the accuracy of numerical results is verified by comparing with the theoretical results. Also, the pressure distribution and load capacity of the rectangular plate holder of a piston pump are obtained by using the CFD software. The results show that the load capacity of the square plate holder with grooves is slightly higher at a low gap thickness, but the effects of the number and arrangement of grooves on the load capacity of the holder are weak. We conclude that the load capacity and the maximum pressure are slightly affected due to the existence of grooves on the holder surface, and the fluid storing effect of the holder surface grooves during the operation is likely to prevent the dry-sticking phenomenon.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.5.2-5.2
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• 2009

From 10 years ago, the development of nano-devices endeavored to achieve reconstruction of information technology (IT) and nano technology (NT) industry. Among the many materials for the IT and NT industry, zinc oxide (ZnO) is a very promising candidate material for the research of nano-device development. Nano-structures of ZnO-based materials were grown easily via various methods and it attracts huge attention because of their superior electrical and optical properties for optoelectronic devices. Recently, among the various growth methods, MOCVD has attracted considerable attention because it is suitable process with benefits such as large area growth, vertical alignment, and accurate doping for nano-device fabrication. However, ZnO based nanowires grown by MOCVD process were had the principal problems of 1st interfacial layers between substrate and nanowire, 2nd a broad diameter (about 100 nm), and 3rd high density, and 4th critical evaporation temperature of Zinc precursors. In particular, the growth of high performance nanowire for high efficiency nano-devices must be formed at high temperature growth, but zinc precursors were evaporated at high temperature.These problems should be repaired for materialization of ultra high performance quantum devices with quantum effect. For this reason, we firstly proposed the growth method of vertical aligned slim MgZnO nanowires (< 10 nm) without interfacial layers using self-phase separation by introduced Mg at critical evaporation temperature of Zinc precursors ($500^{\circ}C$). Here, the self-phase separation was reported that MgO-rich and the ZnO-rich phases were spontaneously formed by additionally introduced Mg precursors. In the growth of nanowires, the nanowires were only grown on the wurzite single crystal seeds as ZnO-rich phases with relatively low Mg composition (~36 at %). In this study, we investigated the microstructural behaviors of self-phase separation with increasing the Mg fluxes in the growth of MZO NWs, in order to secure drastic control engineering of density,diameter, and shape of nanowires.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.2
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• pp.28-35
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• 2003

This study was conducted to identify the characteristics of social carrying capacity at mega-events, especially the 2000 Kwangju Biennale in Korea. In particular, this paper has proposed some management policies for mega events taking into account the relations between social carrying capacity, satisfaction and crowding. The research method was to look into the general characteristics and distributive forms of the location, and then to confirm the possibility of sampling the factors involved in satisfaction degree; last, A factor analysis for causal analysis of perceived crowding was performed. The study needed correlation analysis in order to compare expected crowding and perceived crowding, and performed regression to examine the causality of perceived crowding and satisfaction. The research results were as follows: the correlation of expected crowding, perceived crowding, and the total satisfaction was very low or meaningless. The relation between satisfaction and elements for factor analysis such as convenient facilities and value experience showed partial meaningfulness. The factors of convenient facilities, entrance fee, parking lot use, toilet convenience, and exhibit room use had meaningful results; on the other hand, the factors of value experience showed a meaningful result in the guide service of an event place. In conclusion when those holding an event make a basic project, they should consider management measures for convenience of facilities, proper education for guide service, and systematic guidance. Also, as a method for perceived crowding lower than expected crowding, the study has proposed that it is possible to lower expected crowding by providing appropriate information on the number of tourists expected on the weekends and weekdays. Future research should control variables such as personal characteristics, seasons proper for vacation and holidays, and carefully consider their investigation and design. Moreover, it is necessary to study variables involved in expected crowding of more various space-intensive sightseeing places (mesa-events).