• International Journal of Naval Architecture and Ocean Engineering
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• 제10권4호
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• pp.491-498
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• 2018

The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1938-1943
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• 2005

Network human-robot interface is an important research topic. In home application, users access the robotic system directly via voice, gestures or through the network. Users explore a system by using the services provided by this system and to some extend users are enable to participate in a service as partners. A service may be provided by a robot, a group of robots or robots and other network connected systems (distributed sensors, information systems, etc). All these services are done in the network environment, where uncertainty such as the unstable network connection, the availability of the partners in a service, exists. Moreover, these services are controlled by several users, accessing at different time by different methods. Our research aimed at solving this problem to provide a high available level, flexible coordination system. In this paper, a multi-agent framework is proposed. This framework is validated by using our new concept of slave agents, a responsive multi-agent environment, a virtual directory facilitator (VDF), and a task allocation system using contract net protocol. Our system uses a mixed model between distributed and centralized model. It uses a centralized agent management system (AMS) to control the overall system. However, the partners and users may be distributed agents connected to the center through agent communication or centralized at the AMS container using the slave agents to represent the physical agents. The system is able to determine the task allocation for a group of robot working as a team to provide a service. A number of experiments have been conducted successfully in our lab environment using Issac robot, a PDA for user agent and a wireless network system, operated under our multi agent framework control. The experiments show that this framework works well and provides some advantages to existing systems.

• 정보처리학회논문지D
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• 제9D권3호
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• pp.501-510
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• 2002

고속통신망과 컴퓨터 기술의 발전과 함께 다양한 멀티미디어 응용서비스가 개발되고 있다. 그 중 인터넷망에서의 영상회의 시스템은 활용도가 매우 뛰어나며 많은 관심을 받고 있으며, 이를 위하여 ITU-T 에서는 H.323으로 표준안을 제정하고 있다. H.323 표준안은 단말기, 다지점 제어장치, 게이트키퍼, 게이트웨이의 4개의 구성 요소로 구성되어 있다. 이 중 게이트키퍼의 역할은 영역의 관리로 상대방의 이름주소를 IP 주소로 변환해 주는 주소변환 서비스, 회의의 시작과 종료를 제어해 주는 회의승인 서비스, 그리고 H.323 단말기들의 대역폭을 관리해 주는 대역폭관리 서비스 등을 들 수 있다. 본 논문에서는 인터넷 환경에서의 영상회의 요소들의 효율적인 관리를 위한 게이트키퍼의 구현에 대하여 기술한다. 실험결과, 대표적인 H.323 단말기인 CUSeeMe와 NetMeeting 이용하여 구현된 게이트키퍼가 표준안을 만족함을 입증한다.

• 정보보호학회논문지
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• 제21권4호
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• pp.125-136
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• 2011

우리나라의 전력분야 제어시스템은 보안에 우수한 폐쇄형 네트워크로 운영되고 있어 보안피해의 심각성을 대체로 인지하지 못하고 있다. 앞으로 스마트그리드 사업이 지속적으로 확대되면 스마트미터에서부터 발전소에 이르기까지 다양한 형태의 사이버공격이 이루어질 수 있다. 향후 스마트미터를 통해 발전소에서 가정집까지의 전체 전력망이 연결되면 보안은 더욱 중요한 요소가 될 것이다. 본 연구에서는 스마트그리드 환경 즉, 외부의 혹독한 환경과 전국적인망에서의 안정적 데이터 전송과 외부로부터의 침입방지를 위해 필요한 가상사설망(VPN) Gateway 구조를 설계 및 구현하였다. 본 연구를 통해 완성된 시제품으로 기 운영 중인 상용제품과 다양한 방식으로 연동 테스트를 시행하였으며, IPSec 방식의 터널링과 ARIA 암호화 알고리즘을 통한 암호화를 통해 전력선통신(PLC) 저압원격검침 분야에 시범 설치되어 보안이 강화된 데이터통신을 하고 있다.

• 한국IT서비스학회지
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• 제12권4호
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• pp.349-367
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• 2013

In MANET, the AODV routing protocol with on-demand method has a problem in large control packet overhead. In order to improve this, we first need a comprehensive analysis of correlation between performance metrics and factors affecting the performance of AODV. Selected parameters based on this analysis make it enable to be a more accurate and fair performance analysis, as well as to reduce the time and effort when constructing a scenario for performance analysis. In this paper, various scenarios are configured to apply AODV by varying the values of factors affecting the performance with network simulator QualNet 5.0, and then the results are analysed using performance metrics proposed by IETF MANET working group. This paper also founds a correlation between performance metrics and factors affecting the performance for AODV routing protocol, choosing the values of factors that represent many of the most maximum and minimum values of each performance metrics, and proposes optimal simulation parameters for a more accurate performance evaluation of routing protocols with minimal scenario in experiments. Next, performance comparison of AODV, DSR and DYMO routing protocols based on the proposed simulation parameters is shown which provides a comparative analysis on the performance of on-demand routing protocols. Results of this paper could be very useful for the researcher or service provider who wants to find nice simulation environment or select a proper routing protocol.

• 산경연구논집
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• 제11권1호
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• pp.19-28
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• 2020

Purpose: This research aims to empirically investigate the motivation of corporate voluntary disclosure by exploring the impact of historical loss on corporate social responsibility disclosure (CSRD). Research design, data, and methodology: This paper takes Chinese A-share listed firms that issued standalone social responsibility reports during the period of 2009-2017 as a sample. Drawing on extant literature, this paper defines historical loss firms as firms with net profit greater than or equal to 0 and undistributed profit less than 0. The tendency score matching method (PSM) is used to find matching samples for historical loss firms. Then OLS regression is conducted to investigate the relationship between historical loss and corporate social disclosure. Results: The results show that historical loss has a significant positive impact on the quality of corporate social responsibility disclosure. After changing the measurement of independent and dependent variables as well as adopting different matching methods to screen the control group, the results still hold. Further research indicates that the relationship between historical loss and CSRD is influenced by corporate financing constraints and industry competition. Conclusions: This research supports the resource motivation hypothesis of corporate social responsibility disclosure, and provides empirical evidence for regulators to strengthen supervision on corporate disclosure.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 추계학술대회
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• pp.313-316
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• 2009

지상파 DMB에서는 양방�� 데이터 서비스를 위하여 MPEG-4 BIFS 규격을 사용하고 있다. BIFS는 콘텐츠의 장면을 구성하는 AV, 이미지, 그래픽, 텍스트 등의 다양한 멀티미디어 객체를 장면상에 표현하고, 사용자로부터 입력을 받아 표현된 객체를 조작하도록 하는 것이 가능하다. 그러나 BIFS가 다양한 형태의 입력장치를 갖는 멀티미디어 시스템에 부합되도록 설계되었지만, 오늘날과 같이 제한적 입력장치를 갖는 휴대 단말에 대한 고려가 결여되어 있다. 문제는 DMB 단말들이 제한적 입력을 가질 수밖에 없기 때문에 사용자가 양방향 데이터 콘텐츠를 조작하는 방법이 일관적이지 못하다는 것이다. 본 논문에서는 이러한 문제를 해결하기 위하여 콘텐츠 제공자와 사용자간의 통일되고 효율적인 콘텐츠 조작을 위해 현재의 BIFS 규격에 KeyNavigator 노드를 추가로 정의하였다. KeyNavigator 노드는 BIFS 콘텐츠에서 휴대 단말의 방향키를 이용하여 BIFS 객체간의 이동이나 BIFS 객체를 선택하는 방법을 제공한다. KeyNavigator노드를 사용함으로써 BIFS 콘텐츠 제공자가 의도하는 바에 따라 콘텐츠를 저작할 수 있고 휴대 단말 사용자에게도 통일되고 효율적인 BIFS 콘텐츠 제어 방법을 제시하는 우수한 효과가 있다.

• Journal of Biosystems Engineering
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• 제29권2호
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• pp.167-174
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• 2004

Density is a physical property which contains information relating to the internal quality of fruits and vegetables, and can be used as an index for nondestructive quality evaluation. Density sorting has been employed by farmers for some agricultural products since ancient times. In this study, an automatic density measuring system based on the platform scale or water displacement method was developed for density sorting of watermelon. It consisted of water tan, load cell, net tray, electric motor, limit switch, control system and its program. The resolution of density was 0.001 g/㎤. In order to calibrate and evaluate the accuracy, the density was measured using a balloon kept in cold water. It showed 1.002 g/㎤ which almost correspond to real density of water. Test results with 6 watermelons and 3 replications showed that the standard deviations of the dens were 0.001∼0.004 g/㎤. The relationship between density and internal quality of watermelon was investigated using the system. The densities of hollow watermelons were less than 0.950 g/㎤, it was apparent that the density of the watermelon was related to the degree of hollowness. But the soluble solid contents and internal defects could not be estimated from the density.

• 한국멀티미디어학회논문지
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• 제23권2호
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• pp.186-203
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• 2020

Image-based Virtual Try-On Systems are among the most potential solution for virtual fitting which tries on a target clothes into a model person image and thus have attracted considerable research efforts. In many cases, current solutions for those fails in achieving naturally looking virtual fitted image where a target clothes is transferred into the body area of a model person of any shape and pose while keeping clothes context like texture, text, logo without distortion and artifacts. In this paper, we propose a new improved image-based virtual try-on network system based on keypoints, which we name as KP-VTON. The proposed KP-VTON first detects keypoints in the target clothes and reliably predicts keypoints in the clothes of a model person image by utilizing a dense human pose estimation. Then, through TPS transformation calculated by utilizing the keypoints as control points, the warped target clothes image, which is matched into the body area for wearing the target clothes, is obtained. Finally, a new try-on module adopting Attention U-Net is applied to handle more detailed synthesis of virtual fitted image. Extensive experiments on a well-known dataset show that the proposed KP-VTON performs better the state-of-the-art virtual try-on systems.

• 한국유기농업학회지
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• 제22권4호
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• pp.561-579
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• 2014

This research estimates the necessity of a better governance plan on the purpose of fulfillment energy recovery by building resource recycling system for biomass resources and waste resources that derive from agricultural and mountain village areas. The utilization of new renewable energy technology which uses waste and biomass sources diverse as variety of resources, collecting method, operator etc. and is structurally complicated the formation of policy is also very difficult. There is failure because of the problems which occurs from the policy led by government. Biomass Town Development Project should be made through the central government and the local government integrated support system and should be formed a consultative group in order to process the project mutually with these two department including the experts from the related areas. This consultative group, while government organizations carry out the hub function of strategic knowledge management, should carry out the control tower function to be able to be net working transfer the information with the cooperation of private and government so vitalize the communication area among the related actors. And to be able to increase the participation rate of the local people the consistent and various educations should be given so a smooth business promotion progress will be desired through the change of perception and coactive participation of people.