해상 소형표적 탐색 모형 및 작전운영 방안

이호철(Hocheol Lee),이문걸(Moongul Lee) 육군사관학교 화랑대연구소 2021 한국군사학논집 Vol.77 No.3

Currently, Korea Navy and Coast Guard are conducting search and patrol operations in Korean territorial seas based on their experiences and intuitions from now on. However, these operations have failed frequently due to the characteristics of small targets(like small ship or boat etc), and have caused many arguments and restrictions for search and detection operations. Usually, search operations of small targets have many constraints. The search operations work only if weapon systems such as radar and electro-optical/infra-red equipment reach close to small targets. In this study, we propose an effective search model based on MDP(Markov Decision Process) for limited search spaces and small targets. In addition, we consider realistic maritime environmental characteristics such as fishing nets, sea routes of moving large commercial ship, submerged rock, lighthouse and so on in this model. The various experimental results show that the detection probability of proposed model is significantly better than that of a random search model. We are looking forward to applying this scientific search model for the Korea Navy maritime operation planners.

단면 형상 측정을 이용한 비구면 안경 렌즈의 최적 근사화 된 설계 계수의 추정 방법

이호철(Hocheol Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.5

This paper presents mainly a procedure to get the mathematical form of the manufactured aspherical lens. Generally Schulz formula describes the aspherical lens profile. Therefore, the base curvature, conic constant, and high-order polynomial coefficient should be set to get the approximated design equation. To find the best-approximated aspherical form, lens profile is measured by a commercial stylus profiler, which has a sub-micrometer measurement resolution. The optimization tool is based on the minimization of the root mean square of error sum to get the estimated aspherical surface equation from the scanned aspherical profile. Error minimization step uses the Nelder-Mead simplex (direct search) method. The result of the lens refractive power measurement shows the experimental consistency with the curvature distribution of the best-approximated aspherical surface equation.

일부 고등학생들의 학교와 학원 코로나19 대응방역 신뢰도에 따른 코로나19 예방행동 실천의 차이

이호철(Hocheol Lee),윤혜진(Hyejin Yoon),김지언(Ji Eon Kim),남은우(Eun Woo Nam) 한국농촌의학 지역보건학회 2021 농촌의학·지역보건 Vol.46 No.3

본 연구는 고등학생의 학교와 학원의 코로나19 대응방역에 대한 신뢰도와 이에 따른 코로나19 예방실천의 차이를 비교함에 목적이 있다. 연구 자료는 고등학생을 대상으로 2020년 7월 2일부터 7월 17일까지 온라인 설문조사를 통해 자료를 수집하였으며, 수집된 232명의 고등학생 중 32명을 제외한 200명을 분석하였다. 카이제곱 검정과 이분형로지스틱회귀분석 등을 이용하여 분석하였다. 그 결과, 고등학생은 학교의 코로나19 대응에 대하여 학원보다 더 신뢰하고 있었으며, 학교만 다니는 학생의 코로나19 예방 실천율이 학교와 학원을 다니는 학생보다 높았다. 특히, 오염된 물건 접촉 후의 손씻기(p=.038), 엘리베이터 이용자제(p=.038)이 유의미하게 차이가 있었다. 학교의 코로나19 대응 신뢰정도에 따라서 대중교통기피(p=.028), 일렬착석 식사(p=.011)가 유의미한 차이가 있었으며, 학원의 대응 신뢰정도에 따라 재채기 시 입가림(p=.041)이 유의미한 차이가 있었다. 학교의 대응방역 신뢰도에 영향을 주는 코로나19 예방실천은 3개로 나타났으며, 재채기 시입가림(p=.002), 대중교통 기피(p=.043), 일렬착석식사(p=.025)이었다. 반면에 학원의 대응방역 신뢰도에 영향을 주는 코로나19 예방실천은 1개로 물건 접촉 후 손씻기(p=.039) 였다. 학교의 코로나19 대응방역 신뢰도가 학원보다 높은 이유는 보건교사이다. 보건교사는 교육부의 지침을 받아 코로나19 방역과 학생들에게 코로나19 예방실천 교육을 실시하고 있기 때문이다. 또한, 학원은 코로나19 방역에 대한 지침은 받지만, 이를 책임지고 이행하며 관리할 기관이 명확하지 않다. 따라서, 교육부와 지자체에서는 학원을 대상으로 코로나19 방역을 관리감독하고 코로나19 예방교육을 실시할 임시 순환 보건교사 배치 및 관리 체계를 강화할 필요가 있다. Objectives: This study aimed 1) to investigate high school students’ reliability on COVID-19 responses in schools and private academies and 2) to identify the differences in COVID-19 prevention practice. Methods: This cross-sectional survey collected data from 200 high school respondents, using an anonymous online questionnaire designed by the Yonsei Global Health Center, from July 2 to 17, 2020 in this study. Chi-square tests were conducted to analyze the differences in preventative practices and practice rates between schools and private academies. Binary logistics regression analysis was conducted to identify the factor affecting the reliability of COVID-19 response. Results: These high school students reliabilityed the schools’ COVID-19 response more than the private academy. In addition, students who studied only at school did more COVID-19 prevention practices than students who studied both at school and academy. There was a significant difference in avoiding public transportation (p=.028), sitting in one row while having a meal (p=.011) in the practice rates depending on the schools’ COVID-19 response. A significant difference in Covering the mouth when coughing and sneezing (p-.041) was also found in the practice rates depending on the private academies’ COVID-19 response. Conclusion: The reason why schools were more reliable than private academies was that there are health teachers. Because schools are supervised by the ministry of education, the Ministry of education and local government need to work together to manage and monitor the COVID-19 response in the academies through cooperation between two organizations. In addition, it is necessary to arrange a temporary circulation health teacher who will provide the COVID-19 prevention education at the academies.

대구경 반사경 고속 연마 장치를 위한 적응형 연마헤드

이호철(Hocheol Lee),이남영(Namyoung Lee),송창규(Changkyu Song),박천홍(Chunhong Park),이후상(Husang Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

In this paper, we suggest a polishing head with a mechanical gimbals-like structure for the optics fabrication. In the small tool polishing processes, several types of polishing mechanism have been tried to get more deterministic and high efficient optical fabrication. The conventional polishing processes to use the contacting pad material of polyurethane or pitch need the higher polishing rate to shorten the overall polishing time for large optics. Therefore, new polishing head mechanism is designed to use the air backpressure and gimbals-like hinge structure to increase polishing velocity. In the following experiment, mechanical adaptability was confirmed both on the flat glass and the convex aluminum surface.

자석식 교반기에서 교반 자석의 탈조 검출 장치에 대한 연구

이호철(Hocheol Lee),오정호(Jeongho Oh) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.4

초등학교 체육과 검정교과서 내용 정확성 연구

이호철(Hocheol Lee) 한국스포츠교육학회 2020 한국스포츠교육학회지 Vol.27 No.2

본 연구의 목적은 2015 개정 교육과정에 따른 초등학교 체육과 검정교과서 내용의 정확성을 분석하여 향후 교과서 개발에 필요한 정보를 제공하는 것이다. 분석대상은 3,4학년 검정교과서로 8개의 출판사, 16종이며 분석 매트릭스(matrix)를 통한 질적 텍스트분석과 현직교사 5인으로 구성된 전문가협의를 거쳐 결과를 논의하였다. 연구결과 표지, 삽화와 사진과 관련된 표현지식의 정확성과 명제적, 개념이해 지식으로 명명한 내용지식의 정확성으로 범주화하였다. 표지를 포함한 사진과 삽화는 각 출판사마다의 개성을 바탕으로 학습자 친화적인 내용으로 구성하였으나, 일부 교과서에서는 정확한 운동지식과 3,4학년 학생들의 수준 이해를 간과한 경우가 있었다. 내용지식에서는 일상적으로 통용되는 건강과 운동에 대한 지식을 재고할 필요가 있었으며, 경기규정과 방법, 동작실행에 있어서 정확한 운동원리 등에 관한 오류를 발견할 수도 있었다. 놀이와 게임, 자유형과 크롤영법 등 다양한 용어의 개념에도 일관적인 타당성이 결여된 사례도 있었고 초등학생의 유산소운동 효과, 태권도의 태동과 의미 등과 같이 심도있는 논의가 필요한 면도 있었다. 또한 국가수준 교육과정과의 구체적인 연계방안과 체육과 교과역량과 영역간의 명확한 관계설정 등 보편타당한 개념적 이해가 공유되어야 할 필요가 있었다. 교과서의 구성과 내용은 초등현장 교육의 질을 결정하므로 체육과 검정교과서 개발 시 내용의 정확성은 반드시 재고되어야 한다. The purpose of this study was to analyze the accuracy and site compatibility of the contents of elementary school physical education revised for 2015 to provide information needed for the development of future textbooks. Analysis was conducted on 16 third and fourth grade authorized textbooks from 8 publishers and results were discussed after qualitative text analysis was conducted through an analytic matrix and expert consultations were made with 5 teachers in the elementary school. Research results categorized the accuracy of expressive knowledge related to covers, illustrations, and photographs and the accuracy of content knowledge designated as propositional, concept understanding knowledge. Photographs and illustrations including covers were composed of learner-friendly contents based on the individuality of each publisher but some textbooks overlooked accurate athletic knowledge and a level comprehension of third and fourth grade students. With content knowledge, considerations had to made of common knowledge on health and exercise used in daily life and errors were discovered on accurate exercise principles regarding game regulations, methods, and movement execution. There were also cases in which consistent validity was lacking in the concepts of diverse terms such as playing and games, freestyle and crawl-style swimming, and concepts of various terms such as the birth and meaning of Taekwondo. Also, universally valid conceptual understanding must be shared such as detailed connection systems with educational courses of a national level and clear relationship establishments among physical education, educational capacity, and domains. The composition and contents of textbooks determine the quality of elementary field training so content accuracy during physical education authorized textbook development must be taken into consideration.

폴리싱 고속화를 위한 연마헤드의 회전 안정성과 윤활 상태 평가

이호철(Hocheol Lee),최민석(Minseok Choi) 한국생산제조학회 2016 한국생산제조학회지 Vol.25 No.4

High speed polishing can kinematically increase the polishing removal rate by using the conventional Preston equation, especially for hard substrates such as sapphire or diamond. However, high speed effects should be clarified beforehand considering the lubrication state and process parameter variations. In this paper, we developed a polishing experimental method and apparatus to determine the lubrication state by measuring the real time friction coefficient using two load cells. Through experiments, we obtained a boundary lubrication state above 0.35 of the friction coefficient by using low table speed and high polishing load, indicating a synchronized stable behavior in polishing head rotation. However, larger Stribeck indexes by a high speed above 200 rpm can generate a hydrodynamic lubrication state below 0.25 of the low friction coefficient. This causes the polishing head rotation to stop. A forced and synchronized head rotation is required for high speed polishing.

에어백 공구에 의한 비구면 유리 렌즈 금형의 전면 접촉 연마

이호철(Hocheol Lee),김중억(Junguk Kim) 한국생산제조학회 2008 한국생산제조학회지 Vol.17 No.5

Conventional aspherical lens polishing methods by the small tool polishing use aspherical profile and the trajectory of the polishing tool is also controlled. In this paper, new full contact polishing mechanism is suggested to polish aspherical glass lens mold by both airbag polishing tool and eccentric motion. Full contact concept by airbag polishing tool and no position control make the easy polishing setup and do not need aspherical design profile. An aspherical lens polishing machine was made for this study and a verification experiment was performed for surface roughness improvements.

적응형 공구 및 편심 운동 방식의 광학 연마 기술에 관한 연구

이호철(Hocheol Lee) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.6

In this paper, optics polishing technology using adaptive tool and eccentric motion mechanism was suggested. Optics polishing can make high reflective and accurate surface. The optics polishing process based on the eccentric motion mechanism has been used to manufacture the ophthalmic lens mold. Also ophthalmic lens mold factory hold conventionally a lot of the curved polishing tools for the versatile mold curves of eye diopters and want to reduce tool numbers. Therefore, a polishing machine with adaptive airbag tool was developed and experimentally verified in view of surface roughness and form accuracy.

얇은 고무막 형태의 압력가변 연마헤드를 이용한 웨이퍼평탄도 개선 방법에 관한 연구

이호철(Hocheol Lee) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.4

In this paper, a new polishing head with the variable pressure structure was studied to improve the planarization uniformity of the conventional template-metal head. Metal surface waviness and slurry distribution on the pad have been known to affect the polishing uniformity even in the synchronized quill and platen velocities. A polishing head with silicon rubber sheet was used to get a curved pressure distribution. In the experiment, the vertical deflection behavior on the pad was characterized with back pressure in the air chamber. Quill force increased linearly with backpressure, However, backpressure under a quill force made the upward movements of the quill. In the wafer polishing experiments, polishing rate and polishing thickness distribution were severely changed with backpressure, The best uniformity was observed with the standard deviation of 2.5% level of average polishing removal 215㎚ at backpressure 12.1 kPa.