실외 환경에서 방역임무수행을 위한 자율주행로봇 비주얼 SLAM 시스템

이창식(Changsik Lee),지상훈(Sanghoon Ji),유수정(Sujeong You),Truong Huu Phuc 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10

COVID-19 방역을 위해서 실내외 공간에서의 소독이 일상이 되었다. 일반적으로 소독약을 필요한 곳에 분사하는 형태로 이루어지는데 공원과 같이 실외 넓은 공간에서 소독작업을 할 경우 소독을 하는 인력과 시간이 많이 필요하게 된다. 이러한 점을 보완하기 위해 자율주행로봇을 소독작업 서비스에 투입하여 방역활동을 수행하게 한다. 본 논문에서 실외 공원에서 자율주행로봇이 방역임무수행시 비전을 활용한 SLAM 방법으로 임무수행대상을 검출하고 목표위치까지 이동하여 방역임무를 수행하는 시스템을 제안한다. 실외공원과 같은 광할한 공간에서 전역적인 위치는 GPS 등의 센서기반한 주행을 하고 목표대상을 검출하고 주의에 사람이 있는지 확인하는 임무 수행을 위해서 비전 기반의 SLAM 방법과 인식을 수행한다.

Open N2OS를 활용한 가상 라우터 이중화 프로토콜의 기능 동작과 명령어

이창식(ChangSik Lee),류호용(HoYong Ryu),박재형(Jaehyung Park) 한국디지털콘텐츠학회 2018 한국디지털콘텐츠학회논문지 Vol.19 No.4

Virtual router redundancy protocol (VRRP) was designed as a solution to support fast fail-over in case of network failure. There exists virtual router which acts as default gateway in LAN, and the virtual router is dynamically elected between master and backup router. Through this protocol, end-hosts can be provided seamless network service. However, it needs expensive license fees and maintenance costs to adopt current commercial network operating systems. Furthermore, they are commonly enterprise proprietary software and inherently closed source. In order to tackle these problem, Open N2OS which is open source based open network software platform was developed. It has no dependency on hardware equipment, and provides high availability, scalability, various networking functions. In this paper, we handle VRRP operation and mechanism with related command line interface (CLI).

보부상의 문화유산적 가치

이창식(Lee Changsik) 무형유산학회 2019 무형유산학 Vol.4 No.1

한국 보부상의 문화적 상징성은 생업조직의 관행과 관련된 두레 공동체만큼 상거래민속의 대표 사회공동 조직체이다. 무엇보다 보부상의 공공 문화 요소를 지속적으로 공유해 가야 할 것이다. 보부상 관련 유품에 대한 한국내에서의 문화재적 가치는 국가 및 지방문화재 등의 지정으로 부분적으로 인정을 받은 상태이지만, 『청금록(靑衿錄)』등 기록의 공공성과 보부상놀이 등 무형의 독자성이 널리 부각되지 못하였다. 보부상의 상업공동체 조직 전통과 여기에 파생된 결속형 공문제(公文祭) 의례와 잔치형 놀이 등은 한국 공동체 민속의 대표적 의미를 내포하고 있기에 매우 값지다. 보부상 관련 기록유산은 서양 길드 조직과 다른 공동체 구성을 바탕으로 되어 있다. 기록 자체가 민주적 협력적 활동을 항목별로 살필 수 있다. 보부상 기록유산의 가치는 인적 조직망 속에서 유통의 상부상조, 상행위의 동무의식, 목적에 부합하는 의무이행 등을 세밀하게 기록한 점이다. 보부상 관련 무형유산은 공문제를 통한 결속 도모, 보부상놀이를 통한 상거래(商去來) 활성화와 오일장 축제지향을 보인 점이다. 결국 보부상 민속 체계화는 지속적인 전승력 강화 차원에서 보부상보존회의 포럼과 전통오일장 연계를 병행해야 한다. 이러한 특점을 살려 지역 중심의 오일장과 묶어 문화유산의 등재와 아울러 미래지향적 개발에 집중할 필요성이 있다. Korea’s Bobusang, or travelling merchants of Chosun Dynasty, culturally symbolizes a leading traditional social community of commercial activity just like Dure, or collective farming, which is related to practices of a vocational association. Bobusang’s elements of collectivistic culture should continue to be shared into the future. Whereas values of remaining articles related to Bobusang as cultural heritage have partially been recognized with designation of them as national and regional cultural properties in Korea, intangible uniqueness, such as generality of records, as in Cheong-geum-rok, a roster of Confucius scholars in Chosun Dynasty and folk play of Bobusang, has not been highlighted. Traditions of Bobusang, memorial rites held to deepen ties among members that are part of the traditions and folk play all carry meanings of Korea’s representative community traditions. Documentary heritage of Bobusang is based on a community, which is different from that of a guild in the West. Democratic and cooperative activities are found in the records. The values of documentary heritage lie in detailed descriptions of mutual support for distribution of goods, sense of camaraderie in commercial activity and execution of duties that serves the purpose within Bobusang network. Intangible heritage related to Bobusang attempted to deepen bonds among members through memorial rites, promote commercial activity through a folk play, and pursue festivals. In any case, systematization of Bobusang tradition should be linked to forums held by Bobusang Preservation Society and traditional markets opening at five-day interval to ensure its survival. Based on the afore-mentioned Bobusang’s distinctive features, Bobusang should be registered as a cultural heritage while focus needs to be given to future-oriented development.

소형 셀 환경에서 유틸리티 최대화를 위한 분산화된 방법의 기지국 전송 전력 제어

이창식(Changsik Lee),김지환(Jihwan Kim),곽정호(Jeongho Kwak),김은경(Eunkyung Kim),정송(Song Chong) 한국통신학회 2013 韓國通信學會論文誌 Vol.38 No.12(통신이론)

최근 많은 수의 모바일 유저와 과도한 트래픽 증가를 해결하기 위한 솔루션으로 피코 혹은 펨토 셀과 같은 소형 셀을 설치하는 방법이 주목 받고 있다. 그러나 소형 셀에 속한 엣지 유저들은 주변 기지국으로부터 극심한 셀 간 간섭을 받기 때문에 낮은 평균 전송률을 얻게 되고, 이를 해결하기 위해서는 셀 간 간섭을 효과적으로 관리하는 방법이 필요하다. 최근의 많은 연구들은 셀 간 간섭 관리를 위해 기지국의 전송 전력을 제어하는 알고리즘을 제시하였지만, 제시된 방법들은 높은 복잡도를 가지고 중앙 기지국의 도움을 필요로 한다는 단점이 있다. 본 연구에서는 기지국간의 경쟁을 기반으로 하여, 낮은 복잡도를 가지는 분산화된 방법의 기지국 전송 전력 on/off 제어 및 유저 스케줄링 알고리즘을 제안한다. 시뮬레이션 결과를 통해, 제안하는 방법이 셀 간 간섭 관리를 하지 않는 방법에 비해 셀 엣지 유저의 경우 170%의 성능 개선을 보이고, 최적의 알고리즘과 비교 했을 때 88-96%에 달하는 geometric average throughput (GAT) 성능 및 매우 근접한 average edge user throughput (AET) 성능을 보임을 검증한다. Small cells such as pico or femto cells are promising as a solution to cope with higher traffic explosion and the large number of users. However, the users within small cells are likely to suffer severe inter-cell interference (ICI) from neighboring base stations (BSs). To tackle this, several papers suggest BS transmit power on/off control algorithms which increase edge user throughput. However, these algorithms require centralized coordinator and have high computational complexity. This paper makes a contribution towards presenting fully distributed and low complex joint BS on/off control and user scheduling algorithm (FDA) by selecting on/off pattern of BSs. Throughput the extensive simulations, we verify the performance of our algorithm as follows: (i) Our FDA provides better throughput performance of cell edge users by 170% than the algorithm without the ICI management. (ii) Our FDA catches up with the performance of optimal algorithm by 88-96% in geometric average throughput and sufficiently small gap in edge user throughput.

실외 환경에서 방역임무수행을 위한 자율주행로봇 비주얼 SLAM 시스템

이창식(Changsik Lee),지상훈(Sanghoon Ji),유수정(Sujeong You) 대한전기학회 2021 정보 및 제어 심포지엄 논문집 Vol.2021 No.10

Memory Performance of Electronic Dictionary-Based Commercial Workload

이창식(Changsik Lee),김희철(Hiecheol Kim),이용두(Yongdoo Lee) 한국산업정보학회 2002 한국산업정보학회논문지 Vol.7 No.5

직분식 가솔린 인젝터의 분사 조건에 따른 분무 특성 분석

이기형(Kihyung Lee),이창식(Changsik Lee),이창희(Changhee Lee),류재덕(Jeaduk Ryu),배재일(Jaeil Bae) 한국자동차공학회 2001 한국 자동차공학회논문집 Vol.9 No.5

Recently GDI(Gasoline Direct Injection) engine is spotlighted to achieve higher thermal efficiency under partial loads and better performance at full loads. To realize this system. it is essential to make both stratified combustion and homogeneous combustion. When compared to PFI(Port Fuel Injection)engine. GDI engine needs more complicated control and optimal design with injection system. In addition, spray pattern must be optimized according to injection timing because ambient pressure in combustion chamber is also varied. Thus spray structure should be analyzed in details to meet various conditions. In this experimental study, two types of visualization system were developed to simulate compression stroke and intake stroke, respectively. With an increase of the ambient pressure, the penetration length tends to decrease due to rising resistance caused by the drag force of the ambient air. Spray characteristics impinged on the piston has a significant effect on mixture stratification around the sparkplug. These results provide the information on macroscopic spray structure and design factors for developing GOI injector.

파일럿 분사시의 커먼레일식 직분식 가시화 디젤엔진의 연소 및 Soot분포 특성에 관한 연구

이재용(Jaeyong Lee),한용택(Yongtaek Han),이기형(Kihyung Lee),이창식(Changsik Lee) 한국자동차공학회 2003 한국 자동차공학회논문집 Vol.11 No.6

The objective of this work is to investigate the effect of swirl, injection pressure and pilot injection on D.I. diesel combustion by using a transparent engine system. The test engine is equipped with common rail injection system to obtain high pressure and to control injection timing and duration. In this study, the combustion analysis and steady flow test were conducted to estimate the heat release rate from in-cylinder pressure. Soot distribution in diffusion flame according to swirl ratio, injection pressure and pilot injection was investigated by using LII technique. As the results, high injection pressure was found to shorten ignition delay as well as enhance peak pressure and heat release rate was greatly affected by injection timing and pilot injection. In addition, the results showed that the period of soot formation corresponded to the diffusion flame.<br/>

[가솔린엔진부문] 이중연료 공급 엔진을 이용한 LPG와 가솔린의 연소특성 비교

이창연(Changyoun Lee),이기형(Kihyung Lee),이창식(Changsik Lee) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1

In this paper, we investigated the possibility of LPG as alternative fuel by comparison with gasoline. We designed the dual fuel supplier for LPG and gasoline in order to operate independently using each fuel. The MBT(minimum advance for best torque) data for every engine cod it ion was obtained to analyze the engine performance. In addition, combustion characteristics such as torque, pressure, combustion duration for each engine was measured to compare the engine performance between LPG and gasoline engine. The MBT of LPG is a little advance compared with that of gasoline at the same condition and !lame propagation speed of LPG is faster than that of gasoline. This characteristics made cycle by cycle variation smaller. However, we found that the power of LPG engine was reduced by decreasing of charge efficiency in the high speed region, and it made cycle by cycle variation become worse.

DPIV와 엔트로피 해석방법을 이용한 가시화 엔진내의 유동 특성 및 성층효과에 관한 실험적 연구

이창희(Changhee Lee),이기형(Kihyung Lee),이창식(Changsik Lee) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.1

The objective of tins study is to analyse the spray characteristics according to the injection duration under the ambient pressure cambtian, and the injection timing in the visualization engine In order to investigate the spray behavior, we obtained the spray velocity using the PIV method that has been an useful optical diagnostics technology, and calculated the vorticity from spray velocity component. These results elucidated the relationship between vorticity and entropy which play an Important role in the diffusion process for the early injection case and the stratification process for the late injection case. In addition, we quantified the homogeneous diffusion rate of spray using the entropy analysis based on the Boltzmann's statistical thermodynamics using these method, it was found that the concentration of spray droplets caused by the Increase of injection duration is more effective than the increase of momentum dissipation We also found that the homogeneous diffusion rate increased as the injection timing moved to the early intake stroke process and BTDC 50°was the most efficient injection timing for the stratified mixture formation during the compression stroke.