• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.37-45
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• 2004

In this paper we propose Clustered Group Multicast by Clustering Algorithm in Wireless Mobile Ad-hoc Network. The proposed scheme applies to Weighted Cluster Algorithm Ad-hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any centralized administration or reliable support services such as wired network and base station. In ad hoc network muting protocol because of limited bandwidth and high mobility robust, simple and energy consume minimal. WCGM method uses a base structure founded on combination weighted value and applies combination weight value to cluster header keeping data transmission by seeped flooding, which is the advantage of the exiting FGMP method. Because this method has safe and reliable data transmission, it shows the effect to decrease both overhead to preserve transmission structure and overhead for data transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.995-1000
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• 2016

The maximum cross-correntropy (MCC) algorithm with a set of random symbols keeps its optimum weights undisturbed from impulsive noise unlike MSE-based algorithms and its main factor has been known to be the input magnitude controller (IMC) that adjusts the input intensity according to error power. In this paper, a normalization of the step size of the MCC algorithm by the power of IMC output is proposed. The IMC output power is tracked recursively through a single-pole low-pass filter. In the simulation under impulsive noise with two different multipath channels, the steady state MSE and convergence speed of the proposed algorithm is found to be enhanced by about 1 dB and 500 samples, respectively, compared to the conventional MCC algorithm.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2007-2009
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• 2005

염료감응형 태양전지에 대한 연구 분야에서 다공질 산화물 전극이나 염료 및 전해질 연구에 비해, 상대전극에 대한 연구는 상대적으로 미비한 상태이다. 또한 일반적으로 사용되고 있는 고가의 백금 상대전극을 대체하면서도 촉매 특성이 우수한 새로운 상대전극에 대한 연구의 필요성이 요구된다. 본 연구에서는 우수한 신소재로서 높은 전기전도도 및 전자방출 특성 그리고 높은 표면적을 지니고 있어 전자기기 분야의 다방면에 이용되고 있으며, 최근 대량생산 기술의 개발에 따라 가격이 급격히 하락하고 있는 다중벽 탄소나노튜브(MWCNT)을 이용하여 상대전극을 제조하였다. 이 탄소나노튜브 상대전극을 이용하여 단위 셀을 만들고, 유사 태양광 하에서의 전지의 광전 특성을 측정하였다. 이를 바탕으로 탄소나노튜브 상대전극이 염료감응형 태양전지의 특성 및 수명 안정화에 미치는 영향을 백금 상대전극의 광전 특성과 비교하여 탄소나노튜브의 상대전극으로써의 가능성을 제시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.412-412
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• 2020

기후변화로 인한 강우사상의 변화, 수자원 환경의 변화로 인하여 최근 한반도에 발생한 가뭄시기에 기존의 지표수자원 위주의 수자원 개발은 용수 확보의 측면에서 한계점이 발생하였다. 지하수자원은 최근 지속가능하고 안정적인 수원으로서 역할이 중요해지고 있는 상황이다. 본 연구는 지하수자원의 정량적 평가를 위하여 지하수자원을 대표할 수 있는 인자로 지하수위를 선택하였고, 남원시의 9개 소유역을 대상으로 시공간의 변동을 고려한 월 단위 지하수위 관리 취약성 평가 방법을 개발하였다. 지하수위 취약 시기 평가에서 강수의 지하대수층에 대한 영향을 고려하고 강수 자료의 적용 방법에 따라 유효 우량을 적용하는 방법과 한계침투량 개념을 적용한 강수 자료를 이용하는 방법을 이용하였고 취약 시기 평가 결과를 비교하였다. 지하수위 취약 시기 평가 기준을 개발하고, 엔트로피 방법을 이용하여 가중치를 선정하였으며 다중의사결정 방법을 통해 소유역 별로 지하수자원 취약 시기를 평가하였다. 본 연구에서 개발된 방법은 시공간적인 지하수자원의 효율적 관리 대책 수립의 근거가 될 수 있을 것으로 기대된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.32-39
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• 2017

Recently, usage of mobile cloud services has been increasing. In particular, beyond the constraints of a single cloud computing service, studies on the multi-cloud have been actively pursued. A user must authenticate multiple cloud service providers to use additional cloud services in a multi-cloud. In previous studies, an authentication method using single sign-on (SSO) was not available in all cloud services. Cloud services will not be available when the SSO server is not available due to malicious attacks, because all authentication is done via the SSO server. Additionally, using a broker, there is a vulnerability that can expose authentication information for the service provider to a user who did not sign up. In this paper, we propose a secure user authentication protocol using biometric authentication that does not expose user information when using additional cloud services. The proposed protocol can use a single biometric authentication for multi-cloud services without storing authentication information in each cloud service. In terms of key stability (to ensure stability through the key agreement process and the key area), by disabling various attack methods, such as man-in-the-middle attacks and replay attacks, we provide secure mobile cloud services.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.2
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• pp.105-112
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• 2004

A waste container, one of the key components of a multi-barrier system in a potential high level radioactive waste (HLW) repository in Korea ensures the mechanical stability against the lithostatic pressure of a deep geologic medium and the swelling pressure of the bentonite buffer. Also, it delays potential release of radionuclides for a certain period of time, before it is corroded by intruding impurities. Even though the material of a waste container is carefully chosen and its manufacturing processes are under quality assurance processes, there is a possibility of initial defects in a waste container during manufacturing. Also, during the deposition of a waste container in a repository, there is a chance of an incident affecting the integrity of a waste container. In this study, the appropriate Features, Events, and Processes(FEP's) to describe these incidents and the associated scenario on radionuclide release from a container to the biosphere are developed. Then the total system performance assessment on the Initial waste Container Failure (ICF) scenario was carried out by the MASCOT-K, one of the probabilistic safety assessment tools KAERI has developed. Results show that for the data set used in this paper, the annual individual dose for the ICF scenario meets the Korean regulation on the post closure radiological safety of a repository.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.155-160
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• 2005

Purpose : Many authors have been introduced field in field technique and 3-D conformal radiotherapy that increased the tumor dose as well as decreased the dose of abutting critical organ. These technique have multiple beam direction and small beam segments even below 10 MU(monitor unit)for each field. we have confirmed the influence of low MU on dose output and beam stability. Materials and Methods : To study the dose output, the dose for each field was always 90MU, but it divided into different segment size: 1, 2, 3, 5, 10, 15 segments, 90, 45, 30, 18, 9, 6 MU the measurements were carried out for X-ray energy 4 MV, 6 MV, 10 MV of three LINAC(Varian 600C, 2100C, 2100C, 2100C/D), in addition each measurement was randomly repeated three times for each energy. To study the field symmetry and flatness, X-omat V films were irradiated. After being developed, films were scanned and analyzed using densitometer. Results : Influence of low MU on dose is slightly more increase output about $1.2{\sim}2.9%$ in cGy/mu than 90MU, but may not changed beam quality(flatness or symmetry), Output stability depends on dose rate(PRF)rather than beam energy, field size. Conclusion : Presented result are under the limits(out put<3%, flatness<${\pm}3%$, symmetry<2%). The 3 accelerators are safe to use and to perform conformal radiotherapy treatments in small segments, small MU around 10MU. but Even if the result presented here under the limits, continuous adjustments and periodic QA should be done for use of small MU

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.4
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• pp.91-100
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• 2019

Many university students try to start up a lot because of career uncertainty, and this study reflected this environmental situation. The subject of the study is the degree to which subjective norms of university students affect the start-up intention. In addition, we looked at the mediated effects of self-efficiency and the moderated effects of security competence. To verify the hypothesis of the study, 201 university students in Seoul were asked about the relevant variables. And based on prior theory, hypotheses and questionnaires were made. In addition, the validity, reliability and correlation analysis of each variable were conducted. Multiple regression analysis was used for hypothesis analysis. As a result, subjective norms have a positive effect on the start-up intention. Next, self-efficiency was found to be mediating the relationship between subjective norms and start-up intentions. Finally, when subjective norms affect the start-up intention, security competence showed negative moderate effect. The implications of this study are as follows: First, a positive perception of start-up by those around them is needed when it comes to raising the intention of starting a business. This positive perception also affects the confidence and sense of challenge in start-up and affects their start-up intention. However, if career anchor prefer stable employment for the organization, it can be seen that they negatively affect the start-up intention.

• Journal of KIISE
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• v.42 no.8
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• pp.1057-1064
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• 2015

The tactical network is system based on wireless networking technologies that ties together surveillance reconnaissance systems, precision strike systems and command and control systems. Several alternative paths exist in the network because it is connected as a grid to improve its survivability. In addition, the network topology changes frequently as forces and combatants change their network access points while conducting operations. However, most Internet routing standards have been designed for use in stable backbone networks. Therefore, tactical networks may exhibit a deterioration in performance when these standards are implemented. In this paper, we propose Priority based Multi-Path routing with Local Optimization(PMPLO) for a tactical backbone network. The PMPLO separately manages the global and local metrics. The global metric propagates to other routers through the use of a routing protocol, and it is used for a multi-path configuration that is guaranteed to be loop free. The local metric reflects the link utilization that is used to find an alternate path when congestion occurs, and it is managed internally only within each router. It also produces traffic that has a high priority privilege when choosing the optimal path. Finally, we conducted a simulation to verify that the PMPLO can effectively distribute the user traffic among available routers.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.159-164
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• 2024

The domestic petroleum market is highly sensitive to changes in international oil prices. So, it is important to identify and respond to those changes. In particular, it is necessary to clearly understand the factors causing the price fluctuations of gasoline, which exhibits high consumption. International gasoline prices are influenced by global factors such as gasoline supplies, geopolitical events, and fluctuations in the U.S. dollar. However, previous studies have only focused on gasoline supplies. In this study, we explore the causal relationship between economic indicators and international gasoline prices using various machine learning-based regression models. First, we collect data on various global economic indicators. Second, we perform data preprocessing. Third, we model using Multiple linear regression, Ridge regression, and Lasso(Least Absolute Shrinkage and Selection Operator) regression. The multiple linear regression model showed the highest accuracy at 96.73% in test sets. As a result, Our Multiple linear regression model showed the highest accuracy at 96.73% in test sets. We will expect that our proposed model will be helpful for domestic economic stability and energy policy decisions.