• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.1-8
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• 2001

Conventional microgyroscopes of vibrating type require resonant frequency tuning of the driving and sensing modes to achieve high sensitivity. These tuning conditions depend on each fabricated microgyroscopes, even though the microgyroscopes are identically designed. A new micromachined resonator, which is applicable to microgyroscopes with self-toning characteristics, is presented. Since the laterally driven two degrees of freedom (2DOF) resonator was designed as a symmetric structure with identical stiffness in two orthogonal axes, the resonator is applicable to vibrating microgyroscopes, which do not need mode tuning. A dynamic model of the resonator was derived considering gyroscopic application. The dynamic model was evaluated by experimental comparison with fabricated resonators. The microgyroscopes were fabricated using a simple 2-mask-process of a single polysilicon layer deposited on an insulator layer. The feasibility of the resonator as a vibrating microgyroscopes with self-tuning capability is discussed. The fabricated resonators of a particular design have process-induced non-uniformities that cause different resonant frequencies. For several resonators, the standard deviations of the driving and sensing frequencies were as high as 1232Hz and 1214Hz, whereas the experimental average detuning frequency was 91.75Hz. The minimum detuned frequency was 68Hz with $0.034mVsec/^{\circ}$ sensitivity. The sensitivity of the microgyroscopes was low due to process-induced non-uniformity; the angular rate bandwidth, however, was wide. This resonator could be successfully applicable to a vibrating microgyroscopes with high sensitivity, if improvements in uniformity of the fabrication process are achieved. Further developments in improved integrated circuits are expected to lower the noise level even more.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.4
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• pp.109-120
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• 2016

This study aims to assess vulnerability in urban thermal environments of Seoul by using indicators frequently used in previous studies as well as effective indicators for spatial planning like urban and environmental planning. For this purpose, fifteen indicators that influence urban thermal environments such as heat waves, urban heat island effects, and urban micro-climates were identified based on literature reviews. Indicators for presenting urban structure and spatial properties were included; for example, building volume as 'exposure to climate', buildings completed before 1980 as 'sensitivity', and green space areas as 'adaptive capacity'. Among them, twelve indicators were applied to assess vulnerability in urban thermal environments of Seoul by using a GIS spatial analysis combined with fuzzy logic. The results show that the Gangnam area is identified as more vulnerable to a heat environment as compared to the Gangbuk area. In the Gangnam area, Seocho-gu, Gangnam-gu, Dongjak-gu, Yeongdeungpo-gu, Gangseo-gu were relatively high in vulnerability, while Dongdaemun-gu, Gangbuk-gu, Gwangjin-gu, Jungrang-gu were relatively high in the Gangbuk area. Gwanak-gu, Dobong-gu, Eunpyeong-gu, and Nowon-gu, which include forested areas, have low vulnerability in the sectors of 'exposure to climate' and 'sensitivity' due to the impact of Gwanaksan and Bukhansan. However, some areas with high vulnerability like Seocho-gu and Gangnam-gu may have lower vulnerability if the indicator 'status of air conditioning' from the sector of 'adaptive capacity' is used. This study could support the establishment of a practicable thermal environment policy and spatial planning to reduce heat-related risks in the field of urban and environmental planning.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.52-57
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• 2018

This paper presents the design and cold flow test results of oxidizer-rich preburner injectors for a 9 tonf-class staged combustion engine cycle. Three types of coaxial swirl injectors were designed, and 12 injectors were designed for each type. The diameters of the fuel tangential holes are identical. The diameters of the oxidizer tangential holes were varied to investigate the influence of combustion in the oxidizer-rich preburner according to the momentum ratio of the gas oxidizer generated from combustion in the injector chamber and liquid oxidizer through the cooling channel. It will be verified through a powerpack and combustion test using an oxidizer-rich preburner. In the cold flow test, the fuel flow rate and oxidizer tangential hole flow rate reached the target value based on the designed differential pressure.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.595-603
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• 2018

This study was conducted to understand the growth of attached microbial community in small and medium streams of Gyeonggi-do and the removal efficiency of fluoride with changes in growth. The sites monitoring were carried out for 12 weeks at the P1 and P2(P1 is the point where the discharge water flows. P2 is the downstream point of about 2 km flow), and investigated the water quality and the biomass analysis of the attached microbial community. The growth of the attached microbial community increased up to the 7th investigation, and it was observed that detachment phenomenon occurred. Influencing factors about growth of the attached microbial community were flow rate, velocity, and organic material(T-N & T-P). Meanwhile, fluoride content of attached microbial community also tended to increase until the 7th investigation, and decrease from the 8th. It is assumed that fluoride content has also be reduced with the detachment phenomenon of the attached microbial community. It is expected that this will contribute to the evaluation and management of the use of attached microbial community as a means of stream management. The application of techniques using the attached microbial community should include basic investigation of factors that may affect the growth of the attached microbial community and replacement of the attachment plate according to the time of removal.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.104-111
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• 2019

Staged combustion cycle engines exhibit higher combustion performance compared with open cycle engines with a gas generator. An advanced research of the staged combustion cycle engine is going on for the next program following the KSLV-II program. Various experiments have been carried out for the technology demonstration model, TDM0A and TDM0B. The experiments on the combustion performance are aimed to understand the engine start condition and combustion characteristics. They also aim to develop the oxidizer-rich pre-burner and the combustor of the staged combustion cycle engine. The engine-shaped model, TDM1A is fabricated based on the experimental data. The combustion experiment of the TDM1A shows that the combustion pressure of the combustor is approximately 91 bar and the turbine rotation is approximately 28,00 rpm. The result is stable and satisfies the development requirements. The present paper reports on the development process and characteristics of engine models from TDM0A to TDM1A.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.149-162
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• 2021

This study aims to conduct an empirical analysis on the impact of service quality (performance work, price, physical environment) on customer satisfaction, trust and intention to re-attend ballet performances. Another focus of the research is to examine the structural effect of satisfaction and trust on customer's intention to re-attend. This study surveyed 240 adults (Americans) who have physically attended ballet performances from 2019 to 2020. Applying the structural equation modeling analysis using the software SmartPLS, this study investigates 240 valid responses obtained from a global research institute in a mid-August 2020 survey. The findings of the analysis are as follows. (1) Performance work is positively correlated with customer satisfaction, while price and physical environment do not affect customer satisfaction. (2) Performance work is positively correlated with customer trust. However, price and physical environment haven't been observed to affect customer trust. (3) Customer satisfaction is positively correlated with customer trust. (4) Performance work, price and physical environment do not affect customer's intention to re-attend ballet performances. (5) Customer satisfaction is positively correlated with customer intention to re-attend performances. (6) Customer trust is positively correlated with the intention to re-attend performances.

• Korean small business review
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• v.43 no.4
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• pp.95-115
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• 2021

Quality is an important factor influencing organizational performance, so it should be possible to accurately and effectively measure the quality perceived by members. The Consumer Cooperative can be seen as a retail industry by industry classification, and there are various studies based on the dimension of retail quality, but compared to the general retail industry, few studies have been conducted based on the quality level perceived by members. The purpose of this study is to develop quality dimensions and sub-attributes by analyzing in detail and elaborately how the quality of cooperative is viewed from the perspective of members who are both consumers and owners. To this end, the quality dimension of cooperative quality is needed to be newly developed and quality components are demonstrated based on previous studies on the quality dimension. The quality dimension of the cooperative was developed through prior research to suit the value of the cooperative in product, service, and social responsibility, and a survey was conducted to demonstrate the four major cooperative members in Korea. Through this, sub-dimensions were constructed and the quality dimension of the high-order model was demonstrated through exploratory factor analysis and confirmatory factor analysis. It aims to discover key management elements in terms of quality management and provide practical implications to management.

• The Korea Journal of Herbology
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• v.38 no.5
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• pp.85-95
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• 2023

Objectives : This study was intended to reveal the chemical profiles of aerial(leaf, stem) and underground(rhizome, radix) parts of wild ginseng, and to investigate their anti-aging effects on human skin cells. Methods : Wild ginseng, estimated for over 20 years, was divided into the aerial and underground parts. Total phenolic contents of each extracts were measured using a Folin-ciocalteu method. The contents of 18 amino acids, 8 minerals and 27 ginsenosides were determined by GC-FID, ICP-MS and LC-MS, respectively. The anti-aging effects, including the radical scavenging activity, the activation of mitochondrial function on human fibroblasts, and the proliferation activity on human keratinocyte progenitor cells, for the whole plant and underground part of wild ginseng were evaluated. Results : The total phenolic acids, amino acids, and minerals in the aerial part were more than twice as high as in the underground part. Compared to the cultivated ginseng root, there were various types of ginsenosides in both parts of wild ginseng, and the total amount was more than twice as high. In particular, the aerial part significantly contained ginsenoside F1, F2, C-Mc1, and C-O, and the distinctive patterns that distinguish each parts of wild ginseng from the cultivated ginseng root were derived. The whole plant and underground part of wild ginseng exhibited significant antioxidant effect(14.3-45.6%), activation of mitochondrial membrane potential(105.5-120.1%), and cell proliferation(112.1-125.4%). Conclusions : The entire plant and underground part of wild ginseng are high value-added plants and have beneficial effects on skin anti-aging properties through its abundant metabolites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.176-182
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• 2009

Other damage can occur due to the preexisting dull structure and installation of nonenvironmental-friendly concrete structure, lack of function for preventing coastal erosion. Increase of personal income and fast spread of the concept of waterfront casued the initiation of many project to improve aging coastal ports. However, none of environment-friendly structure has been developed and pre-existing solid block, igloo block, tunnel block are used commonly. In piers and lighter's wharf where the ships are mooring, resonance by the generation of a reflected wave caused by penetration wave in the port and port wave increases wave heights in the port and makes difficult to maintain the temperature, causes problems in mooring ships and cargo-working, and eventually increase the occurance of damages of the small ships by the collision. Therefore, development of new types of blcok is necessary. To apply Coastal Environments block developed for this reason, it requires allowable bearing capacity evaluation of shear key. For this study, we made test specimen for connecting part of C.E. Block, and conducted friction test of boundary surface. Data obtained by the experiment was analyzed by finite element analysis and assessed the coefficient of friction between C.E. Block and boundary surface.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.49 no.3
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• pp.51-59
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• 2012

This paper suggests an efficient method which tracks articulated human body modeled with markov network using disparity map derived from stereo images. The conventional methods which only use color information to calculate likelihood for energy function tend to fail when background has same colors with objects or appearances of object are changed during the movement. In this paper, we present a method evaluating likelihood with both disparity information and color information to find human body parts. Since the human body part are cylinder projected to rectangles in 2D image plane, we use the properties of distribution of disparity of those rectangles that do not have discontinuous distribution. In addition to that we suggest a conditional-messages-update that is able to reduce unnecessary message update of belief propagation. Since the message update has comprised over 80% of the whole computation in belief propagation, the conditional-message-update yields 9~45% of improvements of computational time. Furthermore, we also propose an another speed up method called three dimensional dynamic models assumed the body motion is continuous. The experiment results show that the proposed method reduces the computational time as well as it increases tracking accuracy.