• 한국재료학회지
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• 제31권5호
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• pp.272-277
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• 2021

Owing to its low cost, easy fabrication process, and good ionic properties, aqueous supercapacitors are under strong consideration as next-generation energy storage devices. However, the limitation of the current collector is its poor electrochemical stability, leading to low energy storage performance. Therefore, a reasonable design of the current collector and the acidic electrolyte is a necessary, as well as interfacial engineering to enhance the electrochemical performance. In the present study, graphite foil, with excellent electrochemical stability and good electrical properties, is suggested as a current collector of aqueous supercapacitors. This strategy results in excellent electrochemical performance, including a high specific capacitance of 215 F g^-1 at a current density of 0.1 A g^-1, a superior high-rate performance (104 F g^-1 at a current density of 20.0 A g^-1), and a remarkable cycling stability of 98 % at a current density of 10.0 A g^-1 after 9,000 cycles. The superior energy storage performance is mainly ascribed to the improved ionic diffusion ability during cycling.

• 유통과학연구
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• 제20권5호
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• pp.119-127
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• 2022

Purpose: The purpose of this study is to analyze the Cost-Effectiveness Analysis (CEA) of wholesale and retail brokerage businesses in Korea. And give managerial implications and contribute to academics. Research design, data and methodology: This research empirically analyzes the relationship between expenses and business performance. As for business performance, this research considered two financial performances; sales and profit. As for antecedent variables, this research measured three cost investment expenses; human resource management (HRM), marketing (MKT) and corporate social responsibility (CSR). This research used frequency analysis, correlation analysis, stepwise regression analysis and curve estimation analysis. Results: The result shows that HRM and CSR positive significant influence on sales yet marketing negatively significant influence on sales. And for profit, HRM and CSR give a positive significant influence. However, marketing's influence was not significant. According to curve estimation analysis, the relation between individual cost and performance, best functional relation was all quadratic functions. Some results show ∩ shape and others show shape. Conclusions: Based on this study result, implications for practical management to Wholesale and Retail Brokerage companies in Korea. And the contribution to academics is expected. Also, based on the limitation of this study, future research is suggested.

• Journal of Korea Trade
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• 제27권2호
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• pp.22-46
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• 2023

Purpose - study aims to investigate the relationships between global value chain (GVC)- and transportation-related determinants and economic performance. Also, moderating effects of COVID-19 on the relationships are theoretically and empirically discussed. A limitation of previous studies includes their over-reliance on the opportunities of GVC participation and larger transportation. This study represents the challenges associated with them. Also, it shows how GVC and logistics can be difficult in case of a market fluctuation such as COVID-19. Design/methodology - The sample for this study includes 828 observations from 138 countries. A semi-panel data set has been used. Six observations for each country are used to empirically test the hypotheses and a Two-way cluster model is conducted. Findings - It is confirmed that GVC forward participation contributes more than the backward participation to enhance performance. Transportation infrastructure is critical, but large scales of marine and air transportations are not positive in terms of economic performance. Stricter government response to COVID-19 negatively moderates economic performance by GVC backward participation and transportation infrastructure. Originality/value - The spread of COVID-19 is causing a severe collapse of GVC and transportation. This study empirically verifies the moderating effects of the government stringency on GVC and transportation. Previous studies usually discuss a positive impact of GVC and transportation size on economic performance. However, this study aims to show various challenges behind GVC participation and large scale transportation.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.357-358
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• 2023

Due to recent enhance of safety law and regulations in construction sites, safety inspectors have been more required in construction sites. However, most of them are novice for safety inspection which have not enough experience and skill. Therefore, the novice safety inspector's performance on hazard recognition needs to be improved for effective safety management. The performance of safety inspection is influenced by the inspector's experience and background because the inspection is usually conducted by the inspector's eyes. Therefore, there is a difference in safety inspection performance between novice and experienced safety managers. This study aims to analyze the gap of risk perception between novice and experienced safety managers using quantitative visual data. For this objective, this study conducted eye tracking experiments for novice and experienced group to evaluate cognitive performance of safety risk factors. The results provides the level of safety awareness based on their experience in construction safety. The limitation of this study is a lack of the number of samples used in this study and did not consider the various characteristics of the participants. If these limitations are supplemented in future research, it can be used to develop safety education contents for novice safety managers.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2010년도 춘계학술대회
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• pp.209-217
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• 2010

The importance of performance management has been on the rise, which led to public sectors utilizing BSC performance management system as a tool for adaptability, effectiveness, efficiency, and reorganizational abilities by the public sectors. However, due to lack of fairness of evaluation of performance management, it is difficult to expect high level of acceptance by organizations. Therefore, the purpose of the research is to analyze the acceptance of performance management system by organizations via stabilizing the system within the organization group. The research will utilize BSC performance management system of private sectors to introduce the system to public sectors to show the correlation between fairness of performance management and acceptance of performance management. Theoretical background for correlation between fairness of performance management and acceptance of performance management was created through reviews of documents and theories focusing on performance management. The methodology of the research was shaped through surveying members of organizations of public sectors. To analyze the findings of the data SPSS was exploited to find the statistics regarding frequency, degree of reliability, relevance, and recurrence. To summarize the research findings, the perception of performance management by organization members of public sectors shows positive correlation between fairness and acceptance of performance management, also acceptance of performance management shows positive correlation regards to organization performance. In spite of the findings of the research, the fairness and distribution of performance management was not great. Limitation occurred due to lack of perception and knowledge of performance management of respondents of the survey.

• 대한전자공학회논문지TC
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• 제45권10호
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• pp.90-98
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• 2008

휴대폰에서의 제한된 메모리 용량 및 CPU 성능으로 인하여, 유선망에서의 전자상거래 보안에 사용되는 PKI를 그대로 휴대폰 보안에 사용하기는 적당치 않다. 그러므로 유선망과 비슷한 보안 기능을 제공하면서도 휴대폰에 적용할 수 있는 무선 PKI 기능을 개발할 필요가 있다. 이에 본 논문에서는 경량화되고 안전한 무선 인증서 관리 프로토콜을 제안한다. 제안한 프로토콜은 휴대폰의 제한된 통신 환경 및 성능을 고려하였다. 또한 우리는 제안된 프로토콜에 대하여 시험적으로 구현하였다. 시험 구현에서 무선 인증서 관리 프로토콜의 모듈 사이즈는 휴대폰에 탑재 할 수 있을 정도로 작게 구현되었으나, 보안 기능은 유선망의 인증서 관리 프로토콜의 경우에 비하여 비슷함을 알 수 있었다.

• 대한기계학회논문집B
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• 제33권9호
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• pp.709-717
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• 2009

Heat transfer rate is a very important factor for the performance of a steam reformer because a steam reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam reformer are studied in this paper using numerical method under various operating conditions. Langmuir-Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction. Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses 33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel conversion is decreased because of the heat transfer limitation and short residence time.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.11-19
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• 2015

Due to recent development in mobile devices, the mobile device utilization and many related applications have been increasing. Most of initial applications on mobile devices just showed simple information, but now they processes huge data. However, smart devices have certain limitations in processing massive data. Especially, if the size of data increases, the speed of data processing adversely decreases, so the performance of programs also decreases. If hardware specification of the mobile devices is not enough to handle it, response time will be drastically delayed. To overcome these drawbacks, most of application running on mobile devices communicate with their servers to manage data. XML is a proper language for data communication to send and receive data between servers and mobile devices, because it defines rules of document's format and it is a textual data format and small-sized language. However, mobile devices have limitation such as memory, CPU and wireless network to process huge data and XML also takes a lot of time to communicate with servers and devices and handle data, so it could be overhead in service time. Binary XML is an alternative of performance improvement in data processing, which has XML's benefits and minimizes the XML size by binary coding. However, most of binaryXML which are used on applications don't fit on mobile applications. In this paper, we surveyed many kinds of binaryXML, compared merits and demerits to find a binaryXML for mobile applications. We propose how to use binary XML and implemented an electronic attendance system using binary XML to overcome the limitation of XML and to reduce the load of data communications between servers and devices.

• 한국소음진동공학회논문집
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• 제25권3호
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• pp.184-190
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• 2015

NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

• 한국통신학회논문지
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• 제42권2호
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• pp.413-423
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• 2017

본 논문은 실내에서 위치를 측정하기 위해 초음파와 RF 기반의 실내 측위 시스템을 제안한다. 기존의 실내 측위 방안은 시간 동기화, 시스템의 복잡도, 측위의 정확성 등의 문제가 있다. 이러한 문제를 해결하기 위해 초음파와 무선주파수(RF)를 이용한 송수신 시스템을 제안한다. 송신시스템은 한 쌍의 초음파 송신기와 RF 송신기로 구성하고, 수신시스템은 복수의 초음파 수신기들과 하나의 RF 수신기로 구성한다. 또한, 제안된 시스템이 가질 수 있는 성능의 한계를 수학적으로 분석하였다. 제안된 시스템은 시뮬레이션뿐만 아니라 아두이노 모듈을 이용하여 실제 시스템을 제작하여 측위 성능을 평가하였다. 실내 공간 $2m{\times}2m{\times}2m$에서 25개 지점의 위치를 측정한 결과, 평균 6.1cm, 표준편차 1.6cm의 성능을 보였다.