• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.143-150
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• 2023

As Korea's per capita income increases, participation in various leisure activities to improve the quality of life of the disabled is encouraged. However, in order to participate in leisure activities, movement to the place where the leisure activities are performed must be preceded, so interest in means of transportation for leisure activities of the disabled is increasing. Since manual and electric wheelchairs have their respective disadvantages as means of transportation for leisure activities, interest in power assisting devices for wheelchairs combining the functions of electric wheelchairs with manual wheelchairs is increasing. In this study, the FDA approval process of wheelchair power-assistance products was investigated, and the characteristics of side-attached, front-attached, downward-attached, and rear-attached types of power assist devices for wheelchairs wheelchair in countries around the world were identified. These information will be of great use in helping the disabled and their assistants in Korea to choose the optimal product according to the patient's condition. More usability tests and clinical case studies are needed so that people with disabilities can choose a power assist device suitable for them.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2317-2323
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• 2015

In this paper, we analyze the performance of dual-hop amplify-and-forward (AF) relaying in cooperative networks with partial relay selection. An AF relay gain considered in this paper includes channel-noise-assisted relay gain. Leveraging a received signal-to-noise ratio (SNR) model, we derive exact closed-form expressions for the probability density function (pdf) and cumulative distribution function (cdf) of the end-to-end SNR. Moreover, an exact closed-form expression of the ergodic capacity for dual-hop AF relaying with channel-noise-assisted relay gain and partial relay selection is investigated. The analytical results shown in this paper are confirmed by Monte-Carlo simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.943-951
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• 2006

Multi-input-multi-output (MIMO) systems are considered to improve the capacity and reliability of next generation mobile communication. However, the multiple RF chains associated with multiple antennas are costly in terms of size, power and hardware. Antenna selection is a low-cost low-complexity alternative to capture many of the advantages of MIMO systems. We proposed new joint Tx/Rx antenna selection algorithm with low complexity. The proposed algorithm is a method selects $L_R{\times}L_T$ channel matrix out of $L_R{\times}L_T$ entire channel gain matrix where $L_R{\times}L_T$ matrix selects alternate Tx antenna with Rx antenna which have the largest channel gain to maximize Frobenius norm. The feature of this algorithm is very low complexity compare with Exhaustive search which have optimum capacity. In case of $4{\times}4$ antennas selection out of $8{\times}8$ antennas, the capacity decreases $0.5{\sim}2dB$ but the complexity also decreases about 1/10,000 than optimum exhaustive search.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1106-1114
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• 2003

Several analytic models describe transmission control protocol (TCP) performance such as steady-state throughput as an averaged ratio of number of transmissions to latency. For more detailed analysis of TCP latency, the latency during packet losses are recovered should be considered. In this paper, we derive the expected duration of loss recovery latency considering the number of packet losses recovered by retransmissions. Based on the numerical results verified by simulations, TCP using selective acknowledgement (SACK) option is more effective than TCP NewReno from the aspect of loss recovery latency.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.4
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• pp.141-146
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• 2020

The International Civil Aviation Organization (ICAO) developed Doc 9995 "Manual of Evidence-based Training," with the intention of providing guidance by establishing a new methodology for the development and conduct of a recurrent training and assessment program. The airline pilot training regulations were largely based on the evidence of hull losses from early generation jets, and in order to mitigate a risk, simply repeating an event in a training program was sufficient. At the time, studies concluded that it was time to change the paradigm of training and assessment program for pilots. One airline alone implemented Evidence-Based Training (EBT) program in their flight crew training and assessment program while another airline partially implemented the EBT program. In the regulatory framework of MOLIT, specific EBT regulations have not been established yet. Therefore, it is recommended to develop rules and standards that comply with ICAO SARPs as soon as possible. In this study we review the key steps in the implementation of the baseline EBT, approval process of baseline EBT program, and policy options regarding the implementation of EBT. It will provide guidance to operators, Approved Training Organizations (ATO), and stakeholders.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.57-68
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• 2004

It is very important to construct advanced recall systems in aspects of developing auto industry through strengthening international competitive power, as well as protecting the lives from traffic crashes by vehicle defects. Under the self-certification system, there may be high probability to be defected vehicles because vehicles are sold without testing and approval of governmental sides, even though the system was introduced to give an autonomy to manufactures. Accordingly, it is not optional, but essential concerns to build advanced recall system. As a result of analysis, manufacturers and consumers ask for improvements of domestic recall systems. In this study, policy guidelines were provided on the basis of analyses on several regulations and questionnaires of consumers and manufacturers. The policy guidelines are clearness of recall subjects, prompt collection of vehicle defect information, objective determination of vehicle defects, continuous monitoring of vehicle recalls, etc.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.233-240
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• 2017

In recent years, graphics authoring tools have evolved into a variety of formats in line with the rapidly changing digital design field. However, in the field of interface design, screen shape and size depending on the user's environment, it needs more flexible and scalable authoring tools. Along with the emergence of variety of new tools, work processes are also changing. This study investigates what kinds of graphic authoring tools are currently used by designers and compared the result to the case of overseas and examined the difference in the environment of graphic authoring tool. This study looked at criteria and satisfaction of designers choosing authoring tools and how the choice depends on the type of company we are working in and the type of project we are involved in. Research shows that the choice of authoring tools depends on the type and efficiency of the project. Based on this, a reference is provided to establish the standard and working environment for designers and companies to select graphic authoring tools and propose the future direction of graphic authoring tool environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.515-522
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• 2021

In this paper, we present and analyze a method of applying a machine learning to ultrasonic test signals for constant monitoring of the welding faults in a tubular steel tower. For the machine learning, feature selection based on genetic algorithm and fault signal classification using a support vector machine have been used. In the feature selection, the peak value, histogram lower bound, and normal negative log-likelihood from 30 features are selected. Those features clearly indicate the difference of signals according to the depth of faults. In addition, as a result of applying the selected features to the support vector machine, it has been possible to perfectly distinguish between the regions with and without faults. Hence, it is expected that the results of this study will be useful in the development of an early detection system for fault growth based on ultrasonic signals and in the energy transmission related industries in the future.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.562-582
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• 2022

Although personal media have become a giant industry, there is a lack of understanding of personal media creators. Therefore, this study aims to clarify factors influencing personal media creators' choice of platform. According to the analysis, there is a significant difference between the factors considered by YouTube, AfreecaTV, and Twitch creators. Moreover, the moderating effect of creators' main genre and broadcasting type were also found to be partially significant. It was found that both creators who share the motive of vividness and communication as their main genre and creators who focus on recording and broadcasting with career development motivation prefer YouTube.

• The Korean Journal of Financial Management
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• v.12 no.1
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• pp.167-186
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• 1995

기업인수합병(M&A) 시장의 활성화에 따라 적대적 공개매수를 방어하기 위한 반인수조치(Antitakeover Techniques)들에 관한 관심도 고조되고 있다. 지금까지 널리 알려져 있는 대표적인 반인수 조치들은 Fair Price Amendment(FPA), Classified Board Amendment(CBA)와 Poison Pills(PP) 등이다. 이들 대표적 세 반인수조치들 중에서 FPA와 CBA 채택의 경우는 주주들의 사전 승인이 요구되는데 반하여 PP는 주주들의 사전 승인없이 채택이 가능한 반인수조치이다. 이처럼 상이한 반인수조치들의 채택은 채택기업의 가치에 상이한 부의 효과를 미치는데, 이 분야의 많은 실증적연구 결과들이 보고되고 있다. 본 연구에서는 표본기업으로 현재까지 상호개별적으로 연구되어 왔던 두가지 반인수조치(FTA, CBA)에 PP와 비채택기업도 포함시키고 있다. 지금까지의 반인수조치 채택에 따른 기업가치에 미치는 부의 효과에 관한 연구결과를 확인해보고, 반인수조치 채택에 관한 경영자의 의사결정과 경영자의 부 사이에 체계적인 관계가 존재하는지를 실증분석하고자 한다. 여기서 경영자의 부는 기업내부자 지분율과 기업내 경영자를 위한 Golden Parachute의 존재 유무로 측정한다. 본 연구에서는 3개의 가설을 설정하였다. 가설1: 만일 경영자가 주주의 이익을 희생하면서 자신의 이익을 위한 반인수조치를 채택한다면, 반인수조치 채택의 공표는 평균적으로 기업가치에 부(-)의 효과를 보일 것이다. 가설2: 경영자의 내부지분율이 낮을때 경영자들은 주주에게 가장 해로운 반인수조치를 선택할 것이다. 가설3: Golden Parachute가 존재하지 않을때 경영자들은 주주에게 가장 해로운 반인수조치를 채택할 것이다. 본 연구의 대상기업들중에서 반인수조치 채택 기업들은 IRRC 1990년도판에서 수집되었고, 대칭표본 기업으로 반인수조치를 채택하지 않은 기업들은 CRSP 파일에서 기업규모, SIC 코드를 대응시켜 선정하였다. 임원, 관계이사들과 친인척을 포함하는 내부자의 지분과 Golden Parachute 존재 여부는 이 연구의 표본기업들의 Proxy Statement에서 수집하였다. 최종 표본기업은 FPA 채택기업, CBA 채택기업, PP채택기업, 그리고 비채택기업으로 4개의 상호 배타적인 기업 그룹으로 구성되었다. 본 연구는 Event Study와 Multinomial Logistic Regession의 두가지 실증분석 방법을 사용하였다. Event Study방법론은 반인수조치 채택 공표시 초과수익률을 조사하기 위해 사용하였다. Multinomial Logistic Regession은 선택된 반인수조치 종류와 설명 변수들(내부자 지분율, Golden Parachute)간에 체계적인 관계가 존재하는지를 검증하기 위해 사용되었다. 반인수조치들을 채택하는 기업들은 반인수조치를 채택하고 있지 않은 기업들에 비해 내부자 지분율이 낮게 나타났으며, 반인수조치 중 PP를 채택한 기업에서 가장 낮은 내부지분율을 보이고 있다. GP 채택을 보면 PP를 선택한 기업의 50%가 GP를 채택하였다. 본 연구에서 반인수조치 채택 발표일 하루 전후의 초과수익률을 조사한 결과는 반인수조치 미채택기업, CBA, FPA 채택기업들의 초과수익률은 통계적으로 의미가 없었으나, PP채택에 따른 초과수익률은 의미 있는 부(-)의 값을 나타냈다. 이와같이 CBA와 FPA채택기업들은 주주의 부를 감소시키지 않았으나 PP채택기업들은 주주의 부를 감소시켰다. 따라서 경영자는 주주의 이익을 희생시키면서 자신의 이익을 위해 PP를 선택하고 있음을 보여 주고 있다. 연구결과는 내부자 지분율의 크기가 경영자와 주주간의 이해를 효과적으로 일치시키고 있음을 제시하고 있다. 즉, 내부자 지분율이 큰 기업일수록 반인수조치를 채택하지 않거나 반인수조치 채택시에 주주의 이익에 반하지 않은 반인수조치를 선택하는 경향이 높다. Golden Parachute이 존재하는 기업은 FPA를 채택하거나 반인수조치를 채택하지 않는 것보다 PP나 CBA를 채택하는 경향이 더 높다. 한편 기업에서의 GP의 존재가 경영자의 가장 해로운 반인수조치 선택을 억제하지 못함을 보여주고 있는데, 이는 GP가 비효과적인 계약메카니즘임을 제기한다. GP가 경영자와 주주간의 이해를 일치시키도록하는 계약이라기 보다는 차라리 기업방어전략이 비효과적일때 경영자 자신의 안전판으로 제공되고 있음을 보여준다. 이 논문의 주요공헌은 기업내부자 지분율의 크기와 GP의 존재가 반인수조치 선택에 체계적인 영향을 미치고 있음을 보여준 것이다. 여기서 사용된 Multinomial Logistic모델은 내부지분을 크기와 GP의 존재가 PP또는 CBA가 채택될 것인지를 예측할 수 있게 한다.