• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.386-386
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• 2021

대기 중 온실가스 농도는 인간의 인위적 활동에 의해 증가하고 있으며, 이로 인하여 발생하는 기후변화는 극한 수문 사상에 상당한 영향을 미치고 있다. 특히, 기후변화로 인한 강수 특성의 변화는 홍수, 가뭄, 태풍 등과 같은 극한사상의 변화로 이어지며, 급격한 도시화와 복잡한 사회기반시설물 등과 맞물려 더욱 취약한 홍수위험 문제로 대두된다. 기후변화에 따른 미래의 불확실한 변화에 적응하기 위하여 다양한 기후모델들이 개발되었고, 기후변화와 관련된 많은 응용 연구들이 기후모델에서 모의된 자료를 기반으로 미래를 전망하고 있다. IPCC (Intergovernmental Panel on Climate Change) 제6차 평가보고서(The 6th Assessment Report: AR6)에서는 사회경제 구조의 변화를 반영한 공통사회경제경로 시나리오(Shared Socioeconomic Pathways, SSP) 개념을 도입하였다. SSP 시나리오는 사회경제 변화를 기준으로 기후변화에 대한 완화와 노력에 따라 5개의 시나리오로 구별된다. 기상청 기후정보포털(http://www.climate.go.kr/)에서는 4개 조합의 시나리오(SSP1-RCP2.6, SSP2-RCP4.5, SSP3-RCP7.0, SSP5-RCP8.5) 결과가 제공된다. 자료는 동아시아 지역에 대해 생산한 자료로 25km의 공간해상도를 가지고 있으며, 현재모의기간(1979-2014, S_HIST)과 미래시나리오기간(2015-2020, S_SSP)으로 구분된다. 본 연구에서는 전술한 SSP-RCP 시나리오 조합 중 SSP1-RCP2.6, SSP5-RCP8.5 조합을 이용하여 광주지역 극한강우의 미래 변화를 분석하였다. 시나리오 기반 강우자료의 통계적 특성 분석을 위해 연최대 자료를 추출하여 경향성 및 변동성 분석을 수행하였고, 광주지역 강우 자료에 내재된 특성 변화를 정량적으로 분석하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.2
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• pp.82-89
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• 2023

Due to the characteristics of ship structure, the compartment structure is complicated and narrow, so safety accidents frequently occur during the work process. The main causes of accidents include structural collisions, falling objects, toxic substance leaks, fires, explosions, asphyxiation, and more. Understanding the on-site conditions of workers during accidents is crucial for mitigating damages. In order to ensure safety, the on-site situation is monitored using CCTV in the ship, but it is difficult to prevent accidents with the existing method. To address this issue, a smart safety helmet equipped with location identification and voice/video communication capabilities is being developed as a safety technology. Additionally, the smart safety helmet incorporates environmental sensors for temperature, humidity, vibration, noise, tilt (gyro sensor), and gas detection within the work area. These sensors can notify workers wearing the smart safety helmet of hazardous situations. By utilizing the smart safety helmet and environmental sensors, the safety of workers aboard ships can be enhanced.

• Korean Journal of Remote Sensing
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• v.32 no.6
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• pp.551-566
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• 2016

In the satellite remote sensing, the operational environment of the satellite sensor causes image degradation during the image acquisition. The degradation results in noise and blurring which badly affect identification and extraction of useful information in image data. Especially, the degradation gives bad influence in the analysis of images collected over the scene with complicate surface structure such as urban area. This study proposes a multi-stage image restoration to improve the accuracy of detailed analysis for the images collected over the complicate scene. The proposed method assumes a Gaussian additive noise, Markov random field of spatial continuity, and blurring proportional to the distance between the pixels. Point-Jacobian Iteration Maximum A Posteriori (PJI-MAP) estimation is employed to restore a degraded image. The multi-stage process includes the image segmentation performing region merging after pixel-linking. A dissimilarity coefficient combining homogeneity and contrast is proposed for image segmentation. In this study, the proposed method was quantitatively evaluated using simulation data and was also applied to the two panchromatic images of super-high resolution: Dubaisat-2 data of 1m resolution from LA, USA and KOMPSAT3 data of 0.7 m resolution from Daejeon in the Korean peninsula. The experimental results imply that it can improve analytical accuracy in the application of remote sensing high resolution panchromatic imagery.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1387-1401
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• 2016

When a closed access policy in which only an authorized user is allowed to access to a given base station (BS) has been employed in heterogeneous cellular networks, a macro-cell user is used to experience strong cross-tier interference from its adjacent small-cell BSs to which the user is not allowed to access. To mitigate this problem, it has been proposed that a small-cell BS employs a beamforming vector which is orthogonal to the channel of the victim user. However, this technique requires considerable mutual exchange of information among the macro-cell BS, the macro-cell user, and the small-cell BS. In this paper, we propose a cognitive beamforming scheme, in which a small-cell BS employs the beamforming orthogonal to the victim users' channel without any explicit mutual information exchange. Particularly, the small-cell BS finds small- and macro-cell users experiencing the co-tier and cross-tier interferences from it, respectively. Then, it employs a beamforming which is orthogonal to the victim users' channels to mitigate the co-tier and cross-tier interferences. Using the system-level simulation, we demonstrate that the proposed scheme effectively mitigates the cross-tier interference problem.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.9-17
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• 1999

Viscoelastic characteristics of cured phenolic resin/carbon fiber composite materials were investigated through glass transition and degradation reaction processes in the high temperature region up to $400^{\circ}C$. A typical glass transition of the cross-linked thermoset polymer was followed by irreversible degradation reactions, which were exhibited by the increasing storage modulus and loss modulus peak. A degradation master curve was constructed by using the vertical and horizontal shift factors, both of which complied well with the Arrhenius equation in light of the kinetic expression of degradation rate constants. Using an analogy to the Havriliak-Negami equation in dielectric relaxation phenomena, a viscoelastic modeling methodology was developed to characterize the frequency- and temperature-dependent complex moduli of the degrading thermoset polymer composite systems. The temperature-dependent relaxation time of the degrading composites was determined in a continuous fashion and showed a minimum relaxation time between the glass transition and degradation reaction regions. The capability of the developed modeling methodology was demonstrated by describing the complex behavior of the viscoelastic complex moduli of reacting phenolic resin composite systems.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.58-62
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• 2016

In this paper, we propose a pre-processing scheme for improving indoor positioning accuracy in impulsive noise channel environments. The impulsive noise can be generated by multi-path fading effects by complicated indoor structures or interference environments, which causes an increase in demodulation error probability. The proposed pre-processing scheme is performed before a triangulation method to calculate user's position, and providing reliable input data demodulated from a received signal to the triangulation method. Therefore, we studied and proposed an adaptive threshold function for mitigation of the impulsive noise based on wavelet denoising. Through results of computer simulations for the proposed scheme, we confirmed that Bit Error Rate and Signal-to-Noise Ratio performance is improved compared to conventional schemes.

• Journal of Hospice and Palliative Care
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• v.17 no.4
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• pp.278-288
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• 2014

Purpose: The purpose of this study is to analyze types of shared medical decision making by health professionals in a decision making position. Methods: The Q-methodology was used. Q sample was constructed with a total of 35 Q-statements that were offered with a 9-point rating scale. The statements were structured to generate answers that would form a shape of a normal distribution. Answers to Q sample were analyzed using a QUANL PC program. Results: Four types of shared medical decision making were identified. Type I is patient-centered decision making, Type II is physician-centered, Type III is health professional-centered and Type IV is patient-family-centered. Conclusion: Study results indicate that it is recommended to develop an education program based on the four types of shared medical decision making so that health professionals can be provided with different approaches according to their decision making style.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.29-34
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• 2008

In this paper, we propose the channel sounding scheme which improves the reliability and performance of communication link and mitigate the fading effect of channel in MTMO-OFDM system having correlation between Tx and Rx antennas. And we estimate the channel propagation characteristics of channels between the transmitter and receiver with CS scheme by measuring the channel propagation characteristics using sounding signal. Multi agent system models can be used to analyze the path of the system within any time frame. Further, using this proposed method, we can increase the channel capacity by simple calculation in receiver and transmitter and allocate the optimal power by channel information in transmitter. Also, the increment of channel capacity using the prorposed method is induced as the number of antenna is increased. So, we can anticipate the performance improvement with the presented scheme in more complicated Tx and Rx antenna system.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.476-487
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• 2016

Although the number of adolescents with complicated problems and needs has increased, there has been a limited service for this population. In addition, a traditional social service could not alleviate the problems. In order to provide an alternative to a traditional social service to this population, the wraparound model is reviewed and explored. The study presents a review of literature on wraparound and social work via EBSOCO. By reviewing 12 articles on the subject, the study discovers 3 topics, such as (1) youth with various problems, (2) general characteristics of wraparound, and (3) evidence-based practice and wraparound. Based on 3 topics, the study also discusses the feasibility of wraparound service in Korea.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.108-108
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• 2019

낙동강에는 2010-2012년 4대강 사업 완료 후 8개의 다기능 보가 설치되었다. 보 설치로 인해 물의 체류시간이 증가하고 보 상류에는 정체수역이 광범위하게 형성되었다. 이후 지속된 가뭄과 여름철 고온현상이 겹치면서 남조류의 과잉성장(녹조현상)이 빈번히 발생하여 수생태계 건강성에 문제를 초래하는 등 사회적 이슈로 자리잡게 되었다. 조류의 과잉성장을 해결하기 위해 정부에서는 총인(TP) 방류수 수질기준 강화, 펄스형 방류기법 운영 등 대책을 추진하였으며, 녹조 우심지역을 선정하고 지역 특성에 맞는 대응방안을 수립하여 추진하고 있으나, 그 효과가 국부적이고 일시적이어서 근원적 대책 마련이 필요한 실정이다. 일반적으로 남조류의 과잉성장에 영향을 미치는 요소는 높은 영양염류(질소, 인)와 유기물 농도, 고온과 안정적인 성층강도, 그리고 남조류의 생리적 특성 등으로 매우 다양하기 때문에 정확한 발생 원인의 분석이 어려운 경우가 많다. 그러나, 보에 의해 흐름이 조절되는 하천에서는 유량, 유속 및 수온성층 등이 남조류 성장과 천이특성에 가장 민감한 영향을 미친다. 선행 연구사례에서는 유량과 남조류 생체량이 서로 반비례 관계를 가진다는 점과 상 하층간의 온도차(수온성층)가 남조류 우점과 밀접한 관련이 있다는 것을 보였다(Sherman et al. 1998). 따라서 최근 국내에서도 보의 관리수위를 낮추어 유속을 증가시키고 체류시간을 감소시켜 녹조문제를 완화하려는 노력이 추진 중이다. 하지만 하천의 수질은 물리적, 화학적, 생물학적 요인들의 복잡한 상호작용의 결과이므로, 단기간의 측정 결과로 보 수위 저하의 효과를 평가하는데 어려움이 있다. 따라서 이를 과학적으로 평가하기 위해서 수리 수질 생태의 연동해석이 가능한 수치모델을 활용할 필요가 있다. 수치모델은 매개변수를 충분히 보정한다면, 다른 모든 요인은 동일한 조건에서 보 수위 저하만의 영향을 예측하는데 활용가능하다. 본 연구의 목적은 낙동강 수계 중류에 위치한 칠곡보-강정고령보 구간을 대상으로 3차원 수리 수질모델인 EFDC를 구축하고, 실측 자료를 이용하여 모델을 보정한 후 보 관리수위의 저하운영 시나리오에 따른 수질과 남조류의 시 공간적 변동 특성을 분석하는데 있다.