Flexible and Scalable Formation for Unicycle Robots

Dong Hun Kim(김동헌),Young Kwun Lee(이용권),Sung-Ill Kim(김성일),Wee-Jae Shin(신위재),Hyun-Woo Lee(이현우) 한국지능시스템학회 2005 한국지능시스템학회 학술발표 논문집 Vol.15 No.2

This paper presents a self-organizing scheme for multi-agent swarm systems based on coupled nonlinear oscillators (CNOs). In this scheme, unicycle robots self-organize to flock and arrange group formation through attractive and repulsive forces among themselves. It is also shown how localized distributed controls are utilized throughout group behaviors such as formation and migration. In the paper, the proposed formation ensures safe separation and good cohesion performance among the robots. Several examples show that the proposed method for group formation performs the group behaviors such as reference path following, obstacle avoidance and flocking, and the formation characteristics such as flexibility and scalability, effectively.

Ethylene glycol에 의해 액화된 폐지로부터 polyester 제조

김동헌(Dong Hun Lee),김창준(Chang-Joon Kim),김성배(Sung Bae Kim) 한국생물공학회 2011 KSBB Journal Vol.26 No.3

Polyester was prepared through the esterification reaction between watsepaper liquefied by ethylene glycol and carboxylic acid. Liquefaction was carried out at the previously determined condition of 100 minutes, 160℃, and 3% sulfuric acid, and the hydroxyl value of the liquefied product was 411 mg KOH/g. In order to remove bubbles produced during the curing step, the method to introduce a slight nitrogen stream into reaction vessel and/or the method to preheat a polyester film at 85℃ before curing step were used alone or in combination. But if curing temperature was 130℃, simple method to cure a film for 5 hours at 130℃ without using both methods was found to be most effective. The polyesters prepared with various carboxylic acids showed significant different physical properties, and maleic acid was best among them. Also, the effect of reaction time and temperature, C/H (carboxyl group/hydroxyl group) ratio, and type of additive on the crosslinkage of polyester was investigated. Lithium hydroxide or citric acid as additive was used to enhance the crosslinkage of polyester and citric acid was proved to be much more effective than lithium hydroxide. The effect of reaction temperature on the crosslinkage was marginal, but the crosslinkage decreased above 130℃. The crosslinkage was 86% when the polyester was prepared at an optimum condition such as 130℃ and 15 minutes of reaction condition, 1.5 of C/H ratio, 130℃ and 5 hours of curing condition, and 10% addition of citric acid.

시판 차 음료 속에 함유된 불소의 농도 측정 및 연령별 불소섭취량 추정

한동헌 ( Dong Hun Han ),이운정 ( Un Jung Lee ),김동현 ( Dong Hyun Kim ),김민지 ( Min Ji Kim ),황수정 ( Su Jung Hwang ),김진범 ( Jin Bom Kim ) 대한예방치과·구강보건학회 2010 大韓口腔保健學會誌 Vol.34 No.3

Objectives. The purpose of this study was to analyze the fluoride concentrations of tea drinks which were commercially available in Korea in 2009 and to predict amount of daily fluoride intake from tea drink according to different age groups. Methods. The fluoride concentrations of 20 kinds of tea drinks were assessed by a fluoride ion selective electrode. The estimates of daily fluoride intake were assumed by Dietary Reference Intakes for Koreans 2005. Results. The fluoride concentrations of tea drinks were 0.03~1.72 ppm (mean 0.51 ppm). The calculated amount of daily fluoride intake which were supposed to drink all the sufficient water intake by tea drink of 1.72 ppm fluoride were over maximum intake of fluoride under 9 years olds and over sufficient intake of fluoride in all age groups. Those of 0.51 ppm fluoride were under maximum intake of fluoride in all age groups and over sufficient intake of fluoride under 5 months olds infants. Conclusions. Based on this study, most of the tea drink in Korea contained the appropriate concentration of fluoride. However, consuming some tea drink available in Korean market in large quantities may lead to exposion to a high amount of fluoride which may cause dental fluorosis in infants and young children. Although most of tea drinks are safer to consume, fluoride concentrations of some tea drinks are too low for caries prevention. In countries such as Korea where tea is traditionally consumed, the fluoride concentration and daily safety precautions should be indicated on tea products.

Escaping Route Method in a Trap Situation for Local Path Planning

Dong Hun Kim(김동헌),Hyun-Woo Lee(이현우) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7

This paper presents an escaping route method in a trap situation (a case that the robot is trapped in a local minimum by the potential of obstacles). In this scheme, the APFs for path planning have a multiplicative and additive configuration between APFs for goal destination and APFs for obstacle avoidance unlike conventional configuration where APFs for obstacle avoidance is added to APFs for goal destination. The virtual escaping route method is proposed to allow a robot to escape from a local minimum in trap situation where the total forces composed of repulsive forces by obstacles and attractive force by a goal are zero.

국소 경로 계획법을 위한 APF 기반의 무정형 장애물 회피 연구

이종연(JongYeon Lee),정하민(Hahmin Jung),김동헌(Dong Hun Kim) 한국지능시스템학회 2011 한국지능시스템학회논문지 Vol.21 No.1

본 논문은 국소 경로 계획법을 위한 2차원 센서 환경에서 무정형의 장애물의 회피에 대한 연구를 다루었다. 본 연구는 인공 포텐셜 함수(Artificial Potential Function, APF)를 사용하는 기존의 연구에서 점 형태의 장애물을 다루는 방법을 응용 및 확장한 것으로, 다양한 형태의 크기와 모양을 지니는 장애물에 대해서 두 가지 새로운 형태의 반발 포텐셜 함수를 제안한다. 제안된 방법에 의한 곡률 판단법은 장애물을 단순하게 파악하여, 경로계획에 효율적으로 사용되었다. 실제적인 국소 경로 계획법에 맞게 직선 시야(Line of Sight, LOS)와 로봇의 인지범위(Range)등을 고려하는 알고리즘을 사용하였다. 여러장애물 세트(Set)에 대하여 시뮬레이션 결과를 통하여 제안한 방법과 기존 연구의 차이점을 알아보았으며, 제안한 방법의 장점에 대하여 확인하였다. This paper presents a method about amorphous obstacles avoidance for local path planning in the two-dimensional sensor environment. In particular, the proposed method is extended from some of the recent studies about a point obstacle avoidance. In the paper, repulsive forces of two types are proposed in order that the robot avoids from the amorphous obstacle with various size and form. A judgment of curvatures in the proposed method simplifies the recognition of obstacles to make the path-planning efficient. In addition, the line of sight(LOS) and the range of recognition are considered in the environment. By simulation results, the proposed method for amorphous obstacle avoidance shows better performance than the related existing method and we confirmed advantages of proposed method.

국소 경로 계획법을 위한 APF기반의 무정형 장애물 회피 연구

이종연(JongYeon Lee),정하민(Hahmin Jung),김동헌(Dong Hun Kim) 한국지능시스템학회 2010 한국지능시스템학회 학술발표 논문집 Vol.20 No.1

본 논문은 국소 경로 계획법을 위한 2차원 센서 환경에서 무정형의 장애물의 회피에 대한 연구를 다루었다. 본 연구는 인공 포텐셜 함수(Artificial Potential Function, APF)를 사용하는 기존의 연구에서 점 형태의 장애물을 다루는 방법을 응용 및 확장한 것이다. 본 연구에서는 다양한 형태의 크기와 모양을 지니는 장애물에 대해서 세 가지 새로운 형태의 반발 포텐셜 함수를 제안한다. 국소 경로 계획법애 맞게 직선 시야(Line of Sight, LOS)와 로봇의 인지범위(Range)등을 고려하는 알고리즘을 사용하였다. 다양한 장애물 세트(Set)에 대하여 시뮬레이션 한 결과를 통하여 제안한 방법과 기존의 연구의 차이점을 알아보았으며, 제안한 방법의 장점에 대하여 확인하였다.

전기추진선 무인화를 위한 픽스호크 기반 4ft 쌍동선의 경로 추종 및 장애물 회피 구현

이광국(Kwangkook Lee),김기환(Ki Hwan Kim),이상원(Sang Won Lee),김동헌(Dong Hun Kim) 한국지능시스템학회 2024 한국지능시스템학회논문지 Vol.34 No.3

연료전지 발전시스템에 적용된 고주파 절연형 ZVZCS PS-PWM DC-DC 컨버터의 설계 및 특성 해석

서기영,문상필,김동헌,이현우,권순걸,Suh, Ki-Young,Mun, Sang-Pil,Kim, Dong-Hun,Lee, Hyun-Woo,Kwon, Soon-Kurl 한국조명전기설비학회 2006 조명·전기설비학회논문지 Vol.20 No.4

본 논문에서는 Ballard사의 1.2[kW]급 연료전지와 연료전지의 저전압($28{\sim}43[VDC]$)을 승압(380([VDC])시키기 위한 풀-브리지 직류-직류 컨버터, 그리고 승압된 직류 링크전압을 교류 전압(220[VAC]), 60[Hz]으로 변환하기 위한 단상 풀-브리지 인버터로 구성된 연료전지 발전용 전력변환시스템 중 풀-브리지 고주파 절연형 영전압 영전류 스위칭 위상 천이 펄스폭 변조 직류-직류 컨버터를 제안하였다. 제안한 풀-브리지 고주파 절연형 영전압 영전류 스위칭 위상 천이 펄스폭 변조 직류-직류는 프리휠링 다이오드를 포함한 탭부 인덕터 필터를 이용하여 순환 전류를 저감시켰으며, 스위치 및 변압기의 턴-온, 턴-오프시에 오버슈트 전압이나 과도현상이 발생하지 않는다. 그리고 넓은 출력 전압 조정에도 효율을 $93{\sim}97[%]$정도 얻을 수 있으며, 출력 부하전류의 변화에 대해 거의 일정한 출력 전압 특성을 가졌다. In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.

광범위 시야 정보를 위한 UAV와 UGV의 협업 연구

이재근(Jae-Keun Lee),정하민(Hahmin Jung),김동헌(Dong Hun Kim) 한국지능시스템학회 2014 한국지능시스템학회논문지 Vol.24 No.3

본 논문은 기존의 UGV(Unmanned Ground Vehicle)에서 얻을 수 없었던 광범위한 시야를 얻기 위하여 UGV와 UAV(Unmanned Aerial Vehicle)를 함께 운용하는 플랫폼을 제안한다. UAV는 사용자 조종 없이 UGV 상단의 마커를 인식 한 후 UGV를 추적하며 광범위한 시야를 UGV 사용자에게 전달해 준다. UGV는 사용자가 직접 조정하며, 상단에 마커가 붙어 있는 넓은 알루미늄 판위에 UAV는자동 이륙, 착륙 한다. UAV에는 2개의 카메라가 설치되어 있고, 하나는 마커인식을 위해 다른 하나는 전방의 광범위한 시야를 위하여 사용된다. UAV가 UGV를 추적하는데 있어 인식의 정확도를 높이기 위하여 마커 인식을 사용하였고, 전체 시스템의 통신은 WiFi 통신을 사용하였다. 실험의 결과를 통해 제안된 방법이 광범위 시야 정보를 얻기 위하여 UAV/UGV의 협업 연구에 효과적으로 적용될 수 있음을 보여준다. In this study, a cooperative UAV and UGV platform is proposed to obtain a wide range of visual information. The UAV recognizes a pattern marker on UGV and tracks the UGV without user control. It can provide wide range of visual information for a user in the UGV. The UGV by a user is controled equipped with an aluminum board. And the UAV can take off and land on the UGV. The UAV uses two cameras; one camera is used to recognize a pattern marker and another is used to provide a wide range of visual information to the UGV"s user. It is guaranteed that the proposed visual-based approach detects and tracks the target marker on the UGV, and then lands well. The experimental results show that the proposed approach can effectively construct a cooperative UAV/UGV platform for obtaining a wide range of vision information.

치위생과 학생의 구강건강 지식과 행동변화

이은경 ( Eun Kyoung Lee ),남용옥 ( Young Ok Nam ),김설악 ( Seol Ak Kim ),김민지 ( Min Ji Kim ),한동헌 ( Dong Hun Han ),김진범 ( Jin Bom Kim ) 한국치위생학회 2009 한국치위생학회지 Vol.9 No.4

Objectives: The purpose of this study was to analyze the influence which the professional dental hygiene education has on the knowledge and behavioral change for oral health to the students in the departments of dental hygiene. Methods: 771 students in the first grade and 646 students in the third grade who were attending the departments of dental hygiene from 12 colleges in Korea were surveyed. The self-administered questionnaires were distributed to the students in the colleges during May and asked them to answer the questions and then recovered them on the spot. The collected questionnaires were analyzed by using a SPSS/PC program and the difference of significance depending on the group of the students was tested by Chi-square test or Fisher`s exact probability test. Result: In the number of eating snacks by the students during one day, 2-3 times was the highest, irrespectively of the grade. The rate of the students brushing their teeth after snack was higher in the third-grade students(34.8%) than in the first-grade students(20.8%). As the path of acquiring oral health knowledge, all of the first-grade and third-grade students replied that their school classes had impacted them the most. The rate of toothache experience was a higher tendency in third-grade students compared to the first-grade students(p=0.116). The rate of gingival bleeding experience was lower in the third-grade students than in the first-grade students. The rate of oral prophylaxis experience was higher in the third-grade students than in the first-grade students. In the smoking rate, there was lower in the third-grade students than in the first-grade students. The rate of acknowledging smoking hazard to the periodontal health was higher in the third-grade students than in the first-grade students. Conclusions: This study revealed that the third-grade students of dental hygiene departments who were majoring in dental hygiene had a higher perception of oral health than the first-grade students whose the dental hygiene education period was short.