평판형 집열기를 이용한 덕트 내부유동 해석

고동국(Dong-Guk Ko),윤석주(Suck-Joo Yoon) 대한설비공학회 2000 대한설비공학회 학술발표대회논문집 Vol.2000 No.-

저온 탄화로 실링 챔버내 유로의 형상변화에 따른 내부유동 특성에 관한 연구

고동국(Dong-Guk Ko),압드엘모타립 하마다(Hamada Abdelmotalib),김민우(Min-Woo Kim),이교우(Gyo-Woo Lee),임익태(Ik-Tae Im) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

This paper studies the flow characteristics inside the low-temperature carbonization furnace(LTF) including sealing chamber with labyrinth. The flow behavior inside the furnace was analyzed according to different labyrinth shapes. The effects of labyrinth baffle number, and clearance between upper and lower baffles in the sealing chamber were investigated. The large vortex and recirculation region are generated in the chamber when the baffles of the upper and lower surfaces in the labyrinth are maintained at regular intervals. As a result, the gas discharge flow rate can be reduced by 60.8% when the flow distance between baffle and baffle in labyrinth is reduced to 25% of the baffle length.

섬유의 이송속도와 다공도가 탄화로 내부유동에 미치는 영향

고동국(Dong-Guk Ko),김민우(Min-Woo Kim),라마단 자헤르(Ramadan Zaher),이교우(Gyo-Woo Lee),임익태(Ik-Tae Im) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

원형 및 스월제트의 유동특성에 관한 연구

고동국 ( Dong Guk Ko ),윤석주 ( Suck Ju Yoon ) 한국분무공학회 2014 한국액체미립화학회지 Vol.19 No.2

The comparison of the flow characteristics between circular and swirl jets which were controlled by the spinner attachment inside the airtube were conducted in this study. Swirl jet means a flow in whirls by mixing the flow of axial and tangential direction. Swirl flow has been used for the improvement of the combustion efficiency in the combustor. This flow is controlled by the spinner which has several vanes inclined by certain angles to the axial direction. In this study, angle of vane 30° and diameter ratio of outlet to inlet of the airtube 0.73 were made. These spec. should find on the general gun type burner built in the domestic small size boiler. As the flow characteristics, axial and tangential velocities were measured by using the 2-D hot-wire velocimeter system and analyzed statistically. And also this research conducted a practical experiment considering to the attached belongings likes as ignitor, nozzle etc. on the airtube of the gun type burner. As a result, swirl occurred at the occasion of beingness and flow region extended considerably toward the radial direction. But effect of swirl did not transmit to the downstream. And the complicated flow was appeared regardless of the existence of spinner because of the effect of belongings.

방열핀 형상이 UCD 램프의 방열성능에 미치는 영향

고동국(Dong Guk Ko),김민수(Min Soo Kim) 대한기계학회 2018 大韓機械學會論文集B Vol.42 No.8

본 연구에서는 UCD 램프의 방열성능에 대한 방열핀의 종횡비와 반경의 영향을 해석적 방법을 이용하여 분석하였으며, 해석에 사용된 격자수와 크기는 각각 11,000개와 0.02 mm이다. 방열핀의 전열면적은 4 ㎟로 일정하게 유지시켰으며, 방열핀의 종횡비는 각각 1.0(기본모델), 1.8, 1.41, 0.56 및 0.29이다. 또한 방열핀의 반경 R은 각각 0.0 mm, 0.3 mm, 0.6 mm, 0.9 mm 및 1.2 mm이다. 핀에 가해진 열의 유속과 시간은 각각 1×105 W/㎡과 0.1 초, 0.2 초, 0.5 초, 1 초, 2 초, 5 초 및 10 초이다. 결과적으로 UCD 램프 방열의 방열성능은 핀의 종횡비와 반경이 각각 1.8과 1.2 mm일 경우 가장 우수하였으며, 기본모델보다 5.7% 상승하였다. In this study, the effects of the aspect ratio and radius of the heat dissipation fin on the heat dissipation performance of a UCD lamp were analyzed using an analytical method. The minimum grid size and number of meshes of the fin used for numerical analysis were 0.02 mm and 11,000, respectively. The heat transfer area of the fin was kept constant at 4 mm². The aspect ratios of the fin were 1.0 (base model), 1.8, 1.41, 0.56, and 0.29, and the respective radii of the fin were R=0.0 mm, 0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm. The heat flux and heat flux time applied to the fin were 1×105 W/㎡ and 0.1 s, 0.2 s, 0.5 s, 1 s, 2 s, 5 s, and 10 s, respectively. The heat dissipation performance of the UCD lamp was the best when the aspect ratio and radius of the fin were 1.8 and 1.2 mm, respectively, and showed an increase of 5.7% from the base model.

연소효율 개선을 위한 스월제트의 난류유동 특성에 관한 연구

고동국 ( Dong Guk Ko ),윤석주 ( Suck Ju Yoon ) 한국분무공학회 2014 한국액체미립화학회지 Vol.19 No.2

Swirl flow in the gun type burner has a decisive effect on the stabilization of the flame, improvement of the combustion efficiency, and also a reduction of NOx. This swirl flow is created by the spinner which is inside the airtube that guide the combustion air. Gun type burner has generally the inner devices composed nozzle adapter, spark gap ignitor, and spinner. These inner components change the air flow behavior passing through air tube. Meanwhile, turbulent characteristics of this air flow are important to understand the combustion phenomena in the gun type burner, because the mixture of fuel and air are depended on. However, nearly all of the studies have been analyzed the turbulent flow of simplified combustion formation without the inner devices. So, this study conducted the measurement using by hot-wire anemometer and analyzed turbulent flow characteristics of the swirl flow discharged from the air tube with inner devices. Turbulence characteristics come up in this study were turbulence intensity, kinetic energy and shear stress of the air flow with the change of the distance of axial direction from the exit of the air tube.

방열핀 형상이 UCD램프의 방열성능에 미치는 영향

고동국(Dong Guk Ko),김민수(Min Soo Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

In this study, we propose a method to maximize the heat dissipation performance of a UCD lamp that realizes an 8-wavelength spectrum with sunlight characteristics by using mixed metal and special xenon gas. The aspect ratio and radius of fin were analyzed by analytical method. The minimum mesh size used for the heat dissipation fin was 0.02 mm and the number of mesh was approximately 11,000. In order to understand the effect of the aspect ratio and the radius, the heat transfer area of the fin was kept constant at 4 mm². The fin had an aspect ratio of 1.00(2.00 mm: 2.00 mm(basic model)), 1.41(1.70 mm: 2.40 mm), 1.80(1.50 mm: 2.70 mm), 0.56(2.40 mm: 1.70 mm), and 0.29(2.70 mm: 1.50 mm), respectively. The radius of fin was 0 mm, 0.3 mm, 0.6 mm, 0.9 mm and 1.2 mm, respectively. The heat flux and the heat flux time applied to the fin were 1×10<SUP>5</SUP> W/㎡ and 0.1 second, 0.2 second, 0.5 second, 1 second, 2 seconds, 5 seconds and 10 seconds, respectively. The heat dissipation performance of the UCD lamp was the best when the aspect ratio and radius of the fin were 1.8 and R=1.2 mm.

문제중심학습 기반 STEAM 현장체험학습 프로그램이 초등과학 영재의 과학 탐구 능력, 창의적 문제해결력 및 과학적 태도에 미치는 영향

고동국 ( Ko Dong Guk ),홍승호 ( Hong Seung-ho ) 한국초등과학교육학회 2021 초등과학교육 Vol.40 No.1

In this study, a problem-centered learning based STEAM field experience learning program was developed and the effects of applying it were investigated. The program was composed of 8 sessions by using problem-centered learning education method and integrating STEAM elements between disciplines. The contents of program are as follow. In the step of sharing problems and making a problem-solving plan, they understood the various examples and meanings of endangered species, explored the project activities, and made an inquiry plan. In the search and re-exploration phase, a smart device was used to investigate the appearance, habitat environment and cause of extinction for Clithon retropictus, and a site inquiry plan was established for each group. Then, they moved to the field to explore brackish-headed gallops and discuss ways to protect endangered species. In the step of creating a solution, a web-based report was produced as the final product using smart devices based on the results of the inquiry. In the presentation and evaluation stage, the produced web-based report was used to present each group, conduct mutual evaluation, and organize project activities. The developed program was applied to 6th grade 29 students enrolled in the J University Gifted Education Center. In order to find out the effectiveness of the program, tests of science process skill, creative problem-solving ability, and scientific attitude were conducted before and after of program learning, and the results were statistically analyzed by t-test. In addition, a STEAM program satisfaction test was conducted after project in order to find out the satisfaction of the class. As a result of application of the program, the results were significantly improved in openness, criticism, and creativity among the sub-factors of creative problem-solving ability and scientific attitude. Satisfaction with the STEAM program was also high, but no significant result was found in science process skill. Therefore, the program of this study could be influenced on improvement of creative problem-solving ability and scientific attitude of gifted students in elementary science.

TPACK 기반 융합프로그램 개발 및 적용 - ‘우리 몸의 구조와 기능’ 단원 중 배설 기관을 중심으로 -

고동국 ( Ko¸ Dong Guk ),홍승호 ( Hong¸ Seung-ho ) 한국초등과학교육학회 2021 초등과학교육 Vol.40 No.4

본 연구에서는 초등과학 교육과정의 ‘우리 몸의 구조와 기능’ 단원에서 배설 기관을 주제로 TPACK 기반의 STEAM 프로그램을 개발하여 적용하였다. 프로그램 개발 및 적용은 교육과정 분석 및 학습 목표 세부화, 물리적·심리적 학습 환경 분석, 교수·학습 방법 및 테크놀로지 선정, 수업에 활용할 교사의 TPACK 요인 정리 및 교수·학습자료 개발, 프로그램 적용 및 효과성 검증의 과정으로 진행하였다. STEAM 프로그램 설계 과정에서 고려한 교사의 TPACK은 내용학 지식(배설 기관의 생김새와 하는 일), 교육학 지식(STEAM, 문제 기반 학습, 조사학습, 토의학습, 협동 학습, 과학 글쓰기), 테크놀로지 지식(3D 프린터 및 스마트 기기 활용 기술)과 지식 간의 융합적인 요인이었다. 프로그램은 총 8시간으로 구성되었으며 실험 집단으로 선정된 5학년 학생 29명을 대상으로 적용하였다. 비교 집단의 5학년 27명에게는 교과서 중심으로 개발된 같은 주제의 프로그램을 적용하였다. 프로그램을 적용한 결과 실험 집단은 비교 집단에 비하여 창의적 문제해결력과 과학적 태도에서 유의미한 향상을 보였고 STEAM 프로그램에 대한 만족도도 높게 나타났다. 그러나 두 집단 간의 학업성취도는 유의미한 차이가 없었다. 학생들은 스스로 조사하고 탐구하며 알게 된 지식을 활용하여 문제를 해결하는 과정, 친구들과의 토의 및 협동학습 과정을 통해 창의적 문제해결력이 향상되었던 것으로 보이며 새로운 기술의 활용, 학생 중심의 활동 과정 및 실생활과 관련된 문제를 해결하는 과정에서 과학적 태도와 만족도가 높아진 것으로 판단된다. In this study, a TPACK-based STEAM program was developed and applied under the theme of excretory organs in the ‘Structure and Function of Our Body’ of the elementary science curriculum. The program was produced and conducted through curriculum analysis and learning goal detailing, learning environment analysis, teaching·learning method and technology selection, TPACK elements arrangement and teaching·learning material development, application and effectiveness verification. Teacher's TPACK considered in STEAM program design process is content knowledge (appearance and work of excretory organs), pedagogical knowledge (STEAM, problem-based learning, research learning, discussion learning, cooperative learning, scientific writing) and technology knowledge (3D printer and smart device application technology). The program consisted of a total of 8 hours of project learning activities and was applied to 29 students in the fifth grade as an experimental group. A program of the same theme developed mainly from textbooks was applied to 27 students in the fifth grade of a comparison group. As a result of the application of the program, the experimental group showed significant improvement in creative problem-solving ability and scientific attitude compared to the comparison group, and the class satisfaction with the STEAM program was also high. However, there was no significant difference in academic achievement ability.

3D 프린터를 활용한 호흡계의 융합 수업이 초등학생의 과학 탐구 능력, 창의적 문제해결력, 과학 흥미도 및 STEAM 프로그램 만족도에 미치는 영향

고동국 ( Ko Dong Guk ),홍승호 ( Hong Seung-ho ) 한국초등과학교육학회 2018 초등과학교육 Vol.37 No.3

The aims of this study are to develop the STEAM program focused ‘3D printing for respiratory system’ and to ascertain its influence on elementary student’s science process skills, creative problem solving abilities and scientific interest. The developed STEAM program was applied to 5th grade students of O elementary school located in J city. As a result of applying the STEAM program, the experimental group of the STEAM program class improved significantly in creative problem solving abilities and scientific interest than the control group of the theoretical class. The result of learner satisfaction survey of the STEAM program was high. Meanwhile, there was no significant difference in science process skills between the two groups. Therefore, the STEAM program class with the theme of ‘3D printing for respiratory system’ could be meaningful works to encourage students’ interest as well as their creative problem solving ability and scientific interest. In future, continuous and systematic studies on STEAM programs focused on ‘structure and function of our body’ are needed for elementary students’ cognitive and affective developments.