• The Journal of Asian Finance, Economics and Business
• /
• 제6권4호
• /
• pp.53-63
• /
• 2019

The paper examines the influence of profitability on distance to default (DD) in Vietnam securities market. The investigated sample consists of 211 companies listed on HOSE during 18 years from 2010 to 2017. We apply KMV model to calculate distance to default and use both macroeconomics factors and firm specific factors as independent variables. Using General Least Squared (GLS) method, we find evidence to confirm the positive relationship between profitability and distance to default. This result showed that, although profitability did not directly reflect the cash flow generated, a good profitable enterprise would be an important factor to help facilitate and generate cash flow and at the same time debt was guaranteed when it was due. Besides, the test results revealed that the financial structure and sales on assets have the inverse effect on the distance to default at the significance level of 5%. The results also revealed that a group of macro factors had an influence on the distance to default of businesses, including spread, GDP and trade balance (via exchange rates). Gross domestic income had certain impacts on the distance to default of businesses. This was also a basic indicator measuring the national economic cycle.

• The Journal of Asian Finance, Economics and Business
• /
• 제6권2호
• /
• pp.15-24
• /
• 2019

This study analyzes the effect of the capital structure of Korean manufacturing firms on default risk based on Moody's KMV option pricing model where the probability of default is obtained by measuring the distance to default as a covariant in logit model developed by Merton (1974). Based on the panel data of manufacturing firms, this study achieves its primary objective, using a fixed effect regression model and examines the effect of a firm's capital structure on default risk amongst publicly listed firms on Korea exchange during 2005-2016. Empirical results obtained suggest that the rise in short-term debt to assets leads to increase the risk of default whereas the increase in long-term debt to assets leads to decrease the default risk. The benefits of short-term debt financing over a short-term period fade out in the presence of information asymmetry. However, long-term debt financing overcomes the information asymmetry and enjoys the paybacks of tax advantage associated with long-term debt. Additionally, size, tangibility and interest coverage ratio are also the important determinants of default risk. Findings support the trade-off theory of capital structure and recommend the optimal use of long-term debt in a firm's capital structure.

• 한국산학기술학회논문지
• /
• 제15권2호
• /
• pp.1118-1125
• /
• 2014

본 논문에서는 블랙-숄츠 옵션가격결정이론을 토대로 개발된 KMV 모형을 활용하여 건설업체 예상부도확률(Expected Default Frequency; EDF)을 측정하여 건설업체 경영상태 변동 특성을 건설업체 규모별로 비교분석하는 것을 목적으로 한다. 이를 위해 본 논문에서는 시공능력평가순위 50위권 내에서 국내에 상장된 건설업체 중 28개 업체를 선정하여 상위 14개 업체, 하위 14개 업체로 구분하여 분석에 활용하였다. KMV 모형을 통해 예상부도확률을 측정하기 위해서는 자산가치와 자산가치변동성, 채무불이행점(Default Point)을 먼저 산출하고 이를 기초로 부도거리(Distance to Default)를 측정하여 최종적으로 예상부도확률을 측정하였다. 또한 본 논문에서는 예상부도확률을 2001년 1분기부터 2010년 4분기까지 분기별로 측정하였다. 분석결과 선험적으로 인지하고 있듯이, 대규모 회사가 중소규모 회사보다 재무적으로 건전함을 확인할 수 있었다. 중소규모 회사의 경우 경영상태 변화 추이가 경기변동과는 매우 둔감하게 나타났다. 즉 상대적으로 규모가 작은 회사는 열악한 재무환경이 지속적으로 유지됨을 확인할 수 있었다. 또한 대규모 회사의 경우 전반적으로 중소규모 회사보다 재무적으로 안정적이었지만 경기에 매우 민감하게 반응하는 것으로 나타났다. 이에 따라 급격한 경기변동이 발생했을 때 중소규모 회사보다 체감적으로 재무상황이 급격히 나빠지는 것을 확인할 수 있었다.

• 한국항공운항학회지
• /
• 제30권4호
• /
• pp.23-32
• /
• 2022

Prototype UAMs are shown to us in the market. When the complete product is delivered to market, the efficiency of each UAMs can be compared by default. Before the complete product is shown to us, the comparative study on efficiency of UAMs is performed under the product cost estimation. The efficiency analysis result reveals that both of Lift & Cruise type and vectored thrust type show good efficiency at the initial stage of product. At the near terms stage, five years later from initial stage end, efficiency gets some change. Vectored thrust type of UAMs show best efficiency at the near term stage of product. Because UAMs will be used in urban area, Seoul is the place where the UAMs will be used first. The flying route from Seoul City Hall to Yongsan Park, National Assembly in Yeouido, and City Airport is no more than 10 km distance. For this short distance route, efficiency will make multi-rotor type UAM be prefered to other types. For long distance route or commuting route, life & cruise type and vectored thrust type of UAMs will be prefered on account of operational efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권4호
• /
• pp.1337-1358
• /
• 2015

In this paper, we present an analytical and simulated study on the performance of adaptive vehicular ad hoc networks (VANET) priority based on Transmission Distance Reliability Range (TDRR) and data type. VANET topology changes rapidly due to its inherent nature of high mobility nodes and unpredictable environments. Therefore, nodes in VANET must be able to adapt to the ever changing environment and optimize parameters to enhance performance. However, there is a lack of adaptability in the current VANET scheme. Existing VANET IEEE802.11p's Enhanced Distributed Channel Access; EDCA assigns priority solely based on data type. In this paper, we propose a new priority scheme which utilizes Markov model to perform TDRR prediction and assign priorities based on the proposed Markov TDRR Prediction with Enhanced Priority VANET Scheme (MarPVS). Subsequently, we performed an analytical study on MarPVS performance modeling. In particular, considering five different priority levels defined in MarPVS, we derived the probability of successful transmission, the number of low priority messages in back off process and concurrent low priority transmission. Finally, the results are used to derive the average transmission delay for data types defined in MarPVS. Numerical results are provided along with simulation results which confirm the accuracy of the proposed analysis. Simulation results demonstrate that the proposed MarPVS results in lower transmission latency and higher packet success rate in comparison with the default IEEE802.11p scheme and greedy scheduler scheme.

• 한국멀티미디어학회논문지
• /
• 제20권3호
• /
• pp.437-445
• /
• 2017

Necessity of security reinforcement has been increased these days. As a result, surveillance systems using CCTV and the patrol system by person have been applied to security zone. However, CCTV has a blind spot and CCTV itself cannot handle emergency situation. Patrol system by person is economically expensive. To overcome these disadvantages, this paper presents an image-based surveillance system using unmanned aircraft. As a default, unmanned aircraft traces lines installed on ground which represents path for patrolling. If the aircraft detects objects, then it keeps a constant distance between object without missing the object in the image. Simulation results show that the proposed system can be operated even with unmanned aircraft with low specification.

• 한국의학물리학회지:의학물리
• /
• 제27권4호
• /
• pp.272-276
• /
• 2016

To investigate the optimum x-ray tube design for the dental radiology, factors affecting x-ray beam characteristics such as tungsten target thickness and anode angle were evaluated. Another goal of the study was to addresses the anode heel effect and off-axis spectra for different target angles. MCNPX has been utilized to simulate the diagnostic x-ray tube with the aim of predicting optimum target angle and angular distribution of x-ray intensity around the x-ray target. For simulation of x-ray spectra, MCNPX was run in photon and electron using default values for PHYS:P and PHYS:E cards to enable full electron and photon transport. The x-ray tube consists of an evacuated 1 mm alumina envelope containing a tungsten anode embedded in a copper part. The envelope is encased in lead shield with an opening window. MCNPX simulations were run for x-ray tube potentials of 70 kV. A monoenergetic electron source at the distance of 2 cm from the anode surface was considered. The electron beam diameter was 0.3 mm striking on the focal spot. In this work, the optimum thickness of tungsten target was $3{\mu}m$ for the 70 kV electron potential. To determine the angle with the highest photon intensity per initial electron striking on the target, the x-ray intensity per initial electron was calculated for different tungsten target angles. The optimum anode angle based only on x-ray beam flatness was 35 degree. It should be mentioned that there is a considerable trade-off between anode angle which determines the focal spot size and geometric penumbra. The optimized thickness of a target material was calculated to maximize the x-ray intensity produced from a tungsten target materials for a 70 keV electron energy. Our results also showed that the anode angle has an influencing effect on heel effect and beam intensity across the beam.

• 한국융합학회논문지
• /
• 제10권11호
• /
• pp.111-116
• /
• 2019

최근 컴퓨터 능력의 급속한 발전으로 인간과 컴퓨터간의 상호 작용을 편리하게 연결할 수 있는 많은 기술들이 연구되고 있는 상황으로, 전통적인 입력장치를 사용한 GUI에서 3D 모션, 햅틱, 멀티 터치와 같은 신체를 이용한 NUI로 패러다임이 변화되고 있는 추세이다. 인간의 동작을 센서를 이용하여 컴퓨터에 전달하는 많은 연구가 이루어지고 있으며, 3D 객체를 획득할 수 있는 광학 센서의 개발과 더불어 산업 및 의료 분야, 사용자 인터페이스 분야 등으로 응용 범위가 확장되고 있다. 본 논문에서는 립모션을 기반으로 사용자의 손동작에 따라 기본 입력장치인 마우스를 대신하여 제스처를 통한 타 프로그램 실행 및 윈도우즈 제어가 가능하며, 안드로이드 앱과 융합하여 메인 클라이언트와 연결을 통하여, 음성인식과 버튼을 사용해 각종 미디어와 음성 명령 기능을 통한 제어가 가능한 모델을 제안한다. 제안 모델을 통하여 영상, 음악과 같은 인터넷 미디어를 클라이언트 컴퓨터 뿐만 아니라 앱을 통한 원거리 제어가 가능하여, 편리하게 미디어를 시청할 수 있을 것으로 기대된다.

• 한국컴퓨터정보학회논문지
• /
• 제29권4호
• /
• pp.31-38
• /
• 2024

본 연구는 온라인 원격교육에서 코딩 교육 활성화를 위해, 생성형 AI 기반의 학습 지원 도구개발에 필요한 하이퍼 파라미터 설정을 제안한다. 연구를 위해 세 가지 다른 학습 맥락에 따라 하이퍼 파라미터를 설정할 수 있는 실험 도구를 구현하고, 실험 도구를 통해 생성형 AI의 응답 품질을 평가하였다. 생성형 AI 자체의 기본 하이퍼 파라미터 설정을 유지한 실험은 대조군으로, 연구에서 설정한 하이퍼 파라미터를 사용한 실험은 실험군으로 하였다. 실험 결과, 첫 번째 학습맥락인 "학습 지원"에서는 실험군과 대조군 사이의 유의한 차이가 관찰되지 않았으나, 두 번째와 세 번째 학습 맥락인 "코드생성"과 "주석생성"에서는 실험군의 평가점수 평균이 대조군보다 각각 11.6% 포인트, 23% 포인트 높은 것으로 나타났다. 또한, system content에 응답이 학습 동기에 미칠 수 있는 영향을 제시하면 학습 정서를 고려한 응답이 생성되는 것이 관찰되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권12호
• /
• pp.4912-4933
• /
• 2015

Information Centric Networking (ICN) has recently attracted great attention. It names the content decoupling from the location and introduces network caching, making the content to be cached anywhere within the network. The benefits of such design are obvious, however, many challenges still need to be solved. Among them, the local caching policy is widely discussed and it can be further divided into two parts, namely the cache permission policy and the cache replacement policy. The former is used to decide whether an incoming content should be cached while the latter is used to evict a cached content if required. The Internet is a user-oriented network and popular contents always have much more requests than unpopular ones. Caching such popular contents closer to the user's location can improve the network performance, and consequently, the local caching policy is required to identify popular contents. However, considering the line speed requirement of ICN routers, the local caching policy whose complexity is larger than O(1) cannot be applied. In terms of the replacement policy, Least Recently Used (LRU) is selected as the default one for ICN because of its low complexity, although its ability to identify the popular content is poor. Hence, the identification of popular contents should be completed by the cache permission policy. In this paper, a cache permission policy called Cache-Filter, whose complexity is O(1), is proposed, aiming to store popular contents closer to users. Cache-Filter takes the content popularity into account and achieves the goal through the collaboration of on-path nodes. Extensive simulations are conducted to evaluate the performance of Cache-Filter. Leave Copy Down (LCD), Move Copy Down (MCD), Betw, ProbCache, ProbCache⁺, Prob(p) and Probabilistic Caching with Secondary List (PCSL) are also implemented for comparison. The results show that Cache-Filter performs well. For example, in terms of the distance to access to contents, compared with Leave Copy Everywhere (LCE) used by Named Data Networking (NDN) as the permission policy, Cache-Filter saves over 17% number of hops.