저탄소강 SS41 연속파형 Nd:YAG 레이저 겹치기 용접의 기공제어 기술

이가람(Ka Ram Lee),황찬연(Chan Youn Hwang),양윤석(Yun Seok Yang),박은경(Eun Kyeong Park),유영태(Young Tae Yoo) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.4

With the development of advanced processing technology, laser processing systems, which require high-quality precision processing, have attracted considerable attention. Although laser equipment is expensive, it enables quick processing and less deformation of materials. This technology is often applied to secondary batteries, which has thus far involved the use of argon tungsten inert gas (TIG) welding. However, the welding characteristics of argon TIG welding are not yet good, and a laser is used for welding to address this problem. In this study, lap-joint welding was conducted, and the desired welding characteristics were obtained when the laser power was 1800W and the laser beam travel speed was 1.8 m/min. Lap-joint welding was conducted on Ni-coated SS41. Two cases were compared. No pores were observed in the Ni-coated SS41 lap-joint welding part, and cracks appeared from the lap-joints. Moreover, the pole rod and tap were welded together in a T-joint form to improve the output of the secondary battery. T-joint laser welding showed better welding characteristics than TIG welding.

데이터센터의 신재생에너지 의무비율 달성방안으로 연료전지의 경제성 분석

이가람(Kha Ram Lee),송두삼(Doo Sam Song) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

Data centers, which are the most energy-intensive buildings, install various types of new and renewable energy facilities in accordance with The Energy Use Rationalization Act. Data centers should be constructed with ZEB(Zero-Energy Building) from 2025, and more than 20 percent of its total energy supply should be covered by new and renewable energy. Therefore, the fuel cell will become popular and absolutely necessary in data centers due to good space efficiency. Based on the simulation results and analysis of operation data, the fuel cells hot water production is much higher than its demand. In order to secure economic feasibility and enable continuous operation of fuel cells, it is necessary to adjust the price of LNG for fuel cells, implement a fuel cell power generation support system. Also, the relevant regulations need to be revised so that surplus hot water produced by fuel cells can be sold to the District Heating Corporation or nearby heat-consuming facilities.

데이터센터의 신재생에너지 의무비율 달성방안으로 연료전지의 경제성 분석

이가람(Kha Ram Lee),송두삼(Doo Sam Song) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

Data centers, which are the most energy-intensive buildings, install various types of new and renewable energy facilities in accordance with The Energy Use Rationalization Act. Data centers should be constructed with ZEB(Zero-Energy Building) from 2025, and more than 20 percent of its total energy supply should be covered by new and renewable energy. Therefore, the fuel cell will become popular and absolutely necessary in data centers due to good space efficiency. Based on the simulation results and analysis of operation data, the fuel cells hot water production is much higher than its demand. In order to secure economic feasibility and enable continuous operation of fuel cells, it is necessary to adjust the price of LNG for fuel cells, implement a fuel cell power generation support system. Also, the relevant regulations need to be revised so that surplus hot water produced by fuel cells can be sold to the District Heating Corporation or nearby heat-consuming facilities.

사용자 경험에 기반한 자기주도학습 수학 프로그램 개발

이가람 ( Garam Lee ),김정은 ( Jeongeun Kim ),구성우 ( Seongwoo Gu ),안원주 ( Wonju An ),조규락 ( Kyoolak Cho ) 한국컴퓨터교육학회 2016 컴퓨터교육학회 논문지 Vol.19 No.3

본 연구는 사용자 경험에 기반한 자기주도학습을 위한 수학 프로그램을 개발하는 데 그 목적이 있다. 이를 위해서 교육 프로그램의 일반적인 설계모형인 ADDIE 모형에 따라 분석, 설계, 개발, 실행 및 평가의 과정을 거쳐 프로그램을 설계하고 개발하였다. 프로그램은 자기주도학습 증진을 위한 사용자 경험 요소를 고려하여 구현되었으며, 개발된 프로그램의 특징은 다음과 같다. 첫째, 교수자는 웹으로 편리한 문제출제가 가능하고, 학습자는 어플리케이션을 통해 언제 어디서나 즉시 접속하여 문제를 풀어볼 수 있다. 둘째, 학습자는 풍부한 문제데이터베이스를 기반으로 다양한 유형의 문제풀이와 실시간 질문이 가능하며, 교수자는 그에 대한 즉각적인 피드백이 가능하다. 셋째, 지면 및 동영상 해설 제공과 오답노트의 활용으로 학습자의 순환학습을 가능하게 하며, 교수자는 그룹 성취도 관리를 통하여 학습자의 능동적 학습관리를 지원한다. This study aims to develop user experience based mathematical program for self-directed learning. To meet its aim this program is designed and developed according to the process and method of ``ADDIE``, general design model of education program. The features of this program are as follows. First, teacher can set questions conveniently through intuitive system of web and learner can solve questions at anytime and anywhere through instant access to application. Second, learner can solve different types of questions based on powerful question database and teacher can provide instantaneous feedback on them. Third, learner``s circulation learning can be possible by utilizing paper-video explanation and wrong answer note and teacher supports learner``s active learning management though group achievement management.

다중효용확산형 태양열증류기의 설계 및 성능 비교 분석

이가람(Ga-Ram Lee),임병주(Byung-Ju Lim),조성훈(Sung-Hoon Cho),박창대(Chang-Dae Park) 한국태양에너지학회 2021 한국태양에너지학회 학술대회논문집 Vol.2021 No.11

데이터센터의 신재생에너지 의무비율 달성방안으로 연료전지의 경제성 분석

이가람(Kha Ram Lee),송두삼(Doo Sam Song) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

Data centers, which are the most energy-intensive buildings, install various types of new and renewable energy facilities in accordance with The Energy Use Rationalization Act. Data centers should be constructed with ZEB(Zero-Energy Building) from 2025, and more than 20 percent of its total energy supply should be covered by new and renewable energy. Therefore, the fuel cell will become popular and absolutely necessary in data centers due to good space efficiency. Based on the simulation results and analysis of operation data, the fuel cells hot water production is much higher than its demand. In order to secure economic feasibility and enable continuous operation of fuel cells, it is necessary to adjust the price of LNG for fuel cells, implement a fuel cell power generation support system. Also, the relevant regulations need to be revised so that surplus hot water produced by fuel cells can be sold to the District Heating Corporation or nearby heat-consuming facilities.

협업을 통한 문제해결 과정에서 초등학생들의 협력적 문제해결력을 향상시키는 교실 문화 탐색

이가람(Lee, Ga Ram),박일우(Park, Il-Woo),주은정(Ju, Eunjeong) 학습자중심교과교육학회 2019 학습자중심교과교육연구 Vol.19 No.3

이 연구는 협업을 통해 창의적 문제를 해결하는 과정에서 어떠한 교실 문화가 초등학생들의 협력적 문제해결력을 효과적으로 향상시킬 수 있는지 알아보기 위해 진행되었다. 연구를 위해 초등학교 3학년 학생 24명을 대상으로 창의적 문제해결을 경 험할 수 있도록 과학 단원별로 1학기 4개, 2학기 4개의 팀 과제를 차례로 제시하고 협업을 통해 이를 해결하도록 하였다. 3월과 10월에 각각 사전 사후 검사를 실시한결과, 협업을 통한 문제해결 과정은 학급 구성원들의 협력적 문제해결력 신장에 유의 미한 영향을 준 것으로 나타났다(p<.05). 학생들의 협력적 문제해결력 향상을 가능하게 한 교실 문화를 탐색하였을 때, 참여 학급에는 공동 과제에 대한 몰입이 강화되는 분위기와 팀 과제에 대해 자발적으로 참여하는 교실 문화가 형성되는 것을 관찰할수 있었다. 또한 참여 학급은 팀 내 갈등을 적극적으로 해결하여 허용적 분위기를 만들어 갔으며 구성원들 간에 긍정적인 피드백을 장려하는 문화가 조성되었다. The purpose of this study was to investigate how classroom culture can effectively improve the collaborative problem-solving ability of elementary students in the process of solving creative problems through collaboration. For the study, 24 students in the 3rd grade of elementary school were presented with team work for solving 8 creative problems, As a result of pre and post test in March and October, the problem-solving process through collaboration showed a significant influence on enhancing collaborative problem-solving ability of the class members (p<.05). The results of collecting and analyzing the qualitative data for exploring the classroom culture are these. The classroom culture was observed to be formed, which was enabled students to improve their collaborative problem-solving ability. The participating class has the atmosphere to strengthen the learning flow to the collaborative task and voluntarily participate in the team task. In addition, the participating class actively solved conflicts within the team to create a permissive atmosphere and encouraged positive feedback among members.

압출 가공 wick-free plate가 적용된 다중효용확산 태양열 증류기의 성능 실험

이가람(Lee Ga-Ram),임병주(Lim Byung-Ju),최석민(Choi Seok-Min),박창대(Park Chang-Dae) 한국태양에너지학회 2021 한국태양에너지학회 논문집 Vol.41 No.1

We have developed a wick-free plate (WFP) in which a groove pattern is applied to the surface of a plate to replace the wick-plate, which is a key component of a multi-effect diffusion distiller (MEDD). Wicks and plates act as an evaporation surface and a condensation surface, respectively, in MEDD. However, the wick-plate structure has several problems, such as laborious manufacturing processes and lower durability. Therefore, in this study, WFPs were manufactured using the extrusion method, and MEDD with WFPs was experimentally evaluated. The extrusion method had a lower processing cost and better corrosion-resistance surface than the etching process that was employed in our previous study. The extruded WFP could lower the manufacturing cost by 77% compared to the etched WFP, and had the advantage of absorbing more solar radiation energy by lowering the installation inclination angle by 10°. After fabricating the triple-effect MEDD with the extruded WFPs, an indoor performance experiment was conducted. The results of the solar thermal performance test indicated that WFP-MEDD at 11.7 MJ/(㎡·d) of thermal energy produced 3% higher freshwater than the existing MEDD with a wick-plate.

전력증폭기 부정합 조건에서의 출력 전력 불확도 산출에 관한 연구

이가람(Garam Lee),박영철(Youngcheol Park) 한국전자파학회 2014 한국전자파학회논문지 Vol.25 No.8

본 논문은 전력 증폭기의 출력 전력 측정에 있어 드레인에서의 부정합 정도를 고려한 정교한 측정 불확도 산출 방안을 제시하였다. 기존의 측정 불확도 산출 방법은 최적 성능을 위해 의도적인 부정합을 포함하는 전력증폭기의 정합상황을 정확히 반영하는데 한계를 가지고 있다. 이를 보완하기 위하여, 전력증폭기 드레인의 부정합 정도를 포함하는 복합 반사계수와 S-파라미터 측정 불확도를 활용한 종합적인 전력 측정 불확도를 제안하였으며, 3.7 GHz에서 동작하는 10 watt급 전력증폭기의 출력 전력을 측정한 실제 결과와 비교해 보았다. 결과적으로 제안한 합성 측정 불확도는 기존 불확도에 대비하여 10배 정도의 정교한 출력 전력의 불확도를 얻을 수 있었다. In this paper, an accurate method to estimate the measurement uncertainty of a power amplifier was proposed. Because power amplifiers incorporate mismatch at the drain for the optimal performance, the general method is not enough to produce precise measurement uncertainty of the output power. In order to supplement this method, We suggest comprehensive power measurement uncertainty which is utilized by a complex reflection coefficient and measurement uncertainty of S-parameter which contain the mismatch at the drain on the power amplifier. After that, we compared it with real measurement results of the 10 watt power amplifier which operates on 3.7 GHz. As a result, suggested measurement uncertainty could obtain the uncertainty of output power near 10 times accurate in comparison with existing uncertainty calculation method.

온도변화에 따른 SM45C의 Nd:YAG 레이저 표면경화특성

이가람(K.R. Lee),양윤석(Y.S. Yang),황찬연(C.Y. Hwang),유영태(Y.T. Yoo) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.10