나노 입자 적층 시스템(NPDS)을 이용한 염료 감응 태양전지 - 전기 변색 통합 소자 및 에너지 하베스팅 시스템에 대한 연구

김광민,김형섭,최다현,이민지,박윤찬,추원식,천두만,이선영,Kim, Kwangmin,Kim, Hyungsub,Choi, Dahyun,Lee, Minji,Park, Yunchan,Chu, Wonshik,Chun, Dooman,Lee, Caroline Sunyong 한국마이크로전자및패키징학회 2016 마이크로전자 및 패키징학회지 Vol.23 No.2

본 연구에서는 나노 입자 적층 시스템(Nano Particle Deposition System, NPDS)을 이용하여 전기변색소자의 작동 전극을 적층하고 또한 염료 감응 태양전지의 반도체 층으로 사용되는 $TiO_2$층 및 전기변색소자의 이온 저장 층으로 사용되는 Antimony Tin Oxide(ATO) 층을 제작하였다. NPDS는 상온 건식 분말 적층법으로 노즐을 통하여 초음속으로 가속된 분말의 높은 에너지를 이용하여 기판에 적층하는 새로운 개념의 건식 적층 방법이다. 본 연구에서 코팅된 물질의 두께는 전기변색소자의 투과율에 영향을 끼치는데, 이는 표면 프로파일 측정법(surface profiling method)으로 측정하였으며, 적층된 $TiO_2$와 ATO 및 복합 층의 미세 구조를 확인하기 위해 SEM을 이용한 분석을 진행하였다. 한편 염료 감응 태양전지의 광 변환 효율은 솔라 시뮬레이터로 분석하였다. 또한 UV-visible spectrometer와 power source를 이용하여 630 nm 대역에서 전기 변색 소자가 갖는 투과도 변화와 낮은 전압에서의 작동 및 변색 횟수를 측정하였으며, 결과적으로 상기 과정을 거쳐 제작되고, 측정된 염료 감응 태양전지 - 전기 변색 통합 구조 소자를 자체 제작한 에너지 하베스팅 시스템과 연결하여 통합 구조 소자 내 태양전지의 전압 발생을 통해 자체 구동이 가능한 전기 변색 소자 시스템 제작에 성공하였다. NPDS를 통해 제작된 변색 소자의 경우, 최대 49%의 투과도 변화와 500회 작동에서 C-V curve를 유지함을 측정하여 성능과 내구성을 입증하였고, 통합 소자 내 태양 전지의 광 변환 효율은 최대 2.55%로 측정되었으며, 통합 소자 내 변색 소자의 경우 최대 26%의 투과도 변화를 보였다. In this study, Antimony Tin Oxide (ATO) ion storage layer and $TiO_2$ working electrode were fabricated using Nano Particle Deposition System. NPDS is the cutting-edge technology among the dry deposition methods. Accelerated particles are deposited on the substrate through the nozzle using NPDS. The thicknesses for coated layers were measured and layer's morphology was acquired using SEM. The fabricated electrochromic cell's transmittance was measured using UV-Visible spectrometer and power source at 630 nm. As a result, the integrated electrochromic/DSSC hybrid system was successfully fabricated as an energy harvesting system. The fabricated electrochromic cell was self-operated using DSSC as a power source. In conclusion, the electrochromic cell was operated for 500 cycles, with 49% of maximum transmittance change. Also the photovoltaic efficiency for DSSC was measured to be 2.55% while the electrochromic cell on the integrated system had resulted in 26% of maximum transmittance change.

수치해석을 이용한 소형 승용 차량의 항력 저감장치 개발

김광민(Kwangmin Kim),하성준(Sungjun Ha),김재민(Jaemin Kim),김문상(Moonsang Kim),김용석(Yongsuk Kim),김용년(Yongnyun Kim) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11

인슐레이션을 제거한 소형 초전도 회전자 디자인

김광민(Kwangmin Kim),정성준(Sung-Jun Jung),김경훈(Gyeong-Hun Kim),김남원(Nam-Won Kim),박민원(Minwon Park),유인근(In-Keun Yu),박태준(Tae-Joon Park),김태원(Tae-Won Kim) 대한전기학회 2011 대한전기학회 학술대회 논문집 Vol.2011 No.7

인적 유통에서 혁신적 디자인에 대한 인식 효과: 이층 열차를 중심으로

김광민 ( Kwangmin Kim ),김경진 ( Kyungjin Kim ) 한국유통경영학회 2021 유통경영학회지 Vol.24 No.4

Purpose: This study would like to explore the psychological six factors of consumers for double-decker trains and the five factors of traditional innovation characteristics. Specifically, it will verify that these psychological and innovation characteristic factors exhibit interactive effects on passengers’ attitudes to double-decker trains. Research design, data, and methodology: A total of 60 people with 28 men and 32 women were asked to respond, with an average age of 36.13 years, a minimum of 21 years and a maximum of 45. This study was not conducted as an experimental design, but was conducted in a survey format, so the conditions were not divided. Thus, the median split method distinguished the conditions of psychological and innovation characteristics variables. To verify the research hypotheses, ANOVA and regression analysis were performed. Results: The degree of passengers’ innovativeness has been shown to interact with the perception of the relative advantage of double-decker trains on their attitude. The less innovative passengers responded sensitively to the relative advantage of double-decker trains. On the other hand, innovative passengers generally preferred double-decker trains regardless of their relative advantage. This pattern of interaction effects was repeated among other factors. Implications: For the success of double-decker trains, it is necessary to specifically promote that there are more advantages than single-decker trains, allow them to be observed naturally through TV dramas’ PPL, and give them a chance to board as a trial. In addition, appropriateness and complexity were derived for factors that did not affect the design of double-decker trains. This reflects that passengers already understand the basic needs of double-decker trains and that the use of double-decker trains is not very complicated and is already anticipated. It seems wise to target railway frequent users and male passengers at the beginning of the introduction.

ESG 등급이 기업가치와 부채비용, 신용등급에 미치는 영향

김광민(Kim, Kwangmin),이헌상(Lee, Hoensang) 전북대학교 산업경제연구소 2021 아태경상저널 Vol.13 No.3

본 논문은 2013년부터 2020년 한국거래소의 유가증권시장에 상장된 기업을 대상으로 한국기업지배구조원 ESG 평가 기업의 기업 가치와 부채비용, 신용등급에 관한 연관성을 실증분석하였다. 연구 결과, 첫째 ESG는 기업의 경영성과와 기업 가치에 차별적인 영향을 미치는 것으로 나타났다. 통합부문 ROE와 ROA는 유의하지 않은 값을 확인하였고 토빈 Q는 환경과 사회부문에서 음(-)의 영향을 미치는 것으로 나타났다. 둘째 금융기관으로부터 차입하는 이자율의 결정 요인으로 양호한 ESG 등급은 유의하지 않거나 단기적인 비용의 상승을 유발할 수 있음을 확인하였다. 이는 공적부채와 같이 시장에서의 채권 조달과는 반대로 사적부채의 성격을 지닌 금융기관 등은 해당 기업 대출을 실행함에 있어 비재무적 가치인 ESG를 유의미한 정보로 활용하지는 않는다고 판단할 수 있다. 셋째 비재무적 정보로서 ESG가 회사채 신용등급 평가에 유의미한 양(+)의 관련성을 확인하였다. 신용평가기관은 회계상의 기업 재무 자료뿐만 아니라 비재무적 정보인 ESG의 등급을 신용평가 등급 산정에 반영한다고 볼 수 있다. This paper empirically analyzed the correlation between corporate value, debt cost, and credit rating of ESG-rated companies by the Korea Corporate Governance Service for companies listed on the Korea Exchange from 2013 to 2020. As a result of the study, first, ESG was found to have a differential effect on business performance and corporate value. ROE and ROA in the integrated sector were found to have insignificant values, and Tobin Q was found to have a negative (-) effect in the environmental and social sectors. Second, it was confirmed that a good ESG rating as a determinant of the interest rate borrowed from financial institutions may cause insignificant or short-term cost increases. It can be concluded that financial institutions with the characteristics of private debt do not use ESG, which is a non-financial value, as meaningful information when issuing corporate loans, as opposed to public debt. Third, as non-financial information, ESG confirmed a significant positive (+) relation to corporate bond credit rating evaluation. It can be said that credit rating agencies reflect ESG ratings, which are non-financial information, as well as corporate financial data in accounting in calculating credit ratings.

부유형 해양 광생물반응기의 선택적 투과막의 술폰화 반응을 통한 Biofouling 억제 및 미세조류 생산성 향상

김광민(Kwangmin Kim),이윤우(Yunwoo Lee),김지훈(Z-Hun Kim),박한울(Hanwool Park),정인재(Injae Jung),박재훈(Jaehoon Park),임상민(Sang-Min Lim),이철균(Choul-Gyun Lee) 한국해양바이오학회 2017 한국해양바이오학회지 Vol.9 No.1

The purpose of this study was to inhibit biofouling on a selectively permeable membrane (SPM) and increase biomass productivity in marine photobioreactors (PBRs) for microalgal cultivation by chemical treatment. Surfaces of a SPM, composed of polyethylene terephthalate (PET), was sulfonated to decrease hydrophobicity through attaching negatively charged sulfonic groups. Reaction time of sulfonation was varied from 0 min to 60 min. As the reaction time increased, the water contact angle value of SPM surface was decreased from 75.5o to 44.5o, indicating decrease of surface hydrophobicity. Furthermore, the water permeability of sulfonated SPM was increased from 5.42 mL/㎡/s to 10.58 mL/㎡/s, which reflects higher nutrients transfer rates through the membranes, due to decreased hydrophobicity. When cultivating Tetraselmis sp. using 100-mL floating PBRs with sulfonated SPMs, biomass productivity was improved by 34% compared with the control group (non-reacted SPMs). In addition, scanning electron microscopic observation of SPMs used for cultivation clearly revealed lower degree of cell attachment on the sulfonated SPMs. These results suggest that sulfornation of a PET SPM could improve microalgal biomass productivity by increasing nutrients transfer rates and inhibiting biofouling by algal cells.

MCV 수동화를 기반으로 한 굴삭기 자동정지 제어

김광민(Kwangmin Kim),김민지(Minji Kim),김동목(Dongmok Kim),이동준(Dongjun Lee) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

We propose a passivity-based control framework for the excavator with main control valve (MCV). We first derive mathematical model of a 4-way valve, then develop a passivity-based control rule using spool actuation forces as control inputs. The passivity-based control is done in two steps: 1) MCV passifying control and 2) spool actuation control. First, the flow rate of each valve in MCV is decomposed into active flow source and a passive dissipation, and valve passifying control is presented based on this structure. Second, we present a spool actuation input to control the spool position to the desired value. In addition, we compensate the self-weight in order to make the passivity of the excavator less conservative. Finally, we propose a passivity-based auto-stop function of excavator when it collides with an underground obstacle.

Operating characteristic analysis of a DDC module for a HTS DC reactor magnet

Kwangmin Kim(김광민),Minh-Chau Dinh(딘민차우),Sun-Kyoung Ha(하선경),Ki-Yook Yun(윤기욱),Seokho Kim(김석호),Hea-Chul Park(박희철),Sangjin Lee(이상진),Minwon Park(박민원),In-Keun Yu(유인근) 대한전기학회 2013 대한전기학회 학술대회 논문집 Vol.2013 No.7

풍력발전용 피치 드라이브 시스템의 복합 유성기어류에 대한 피로 강도해석

김광민(KwangMin Kim),배명호(MyungHo Bae),조연상(YonSang Cho) 한국트라이볼로지학회 2021 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.37 No.2

Wind energy is considered as the most competitive energy source in terms of power generation cost and efficiency. The power train of the pitch drive for a wind turbine uses a 3-stage complex planetary gear system in being developed locally. A gear train of the pitch drive consists of an electric or hydraulic motor and a planetary decelerator, which optimizes the pitch angle of the blade for wind generators in response to the change in wind speed. However, it is prone to many problems, such as excessive repair costs in case of failure. Complex planetary gears are very important parts of a pitch drive system because of strength problem. When gears are designed for the power train of a pitch drive, it is necessary to analyze the fatigue strength of gears. While calculating the specifications of the complex planetary gears along with the bending and compressive stresses of the gears, it is necessary to analyze the fatigue strength of gears to obtain an optimal design of the complex planetary gears in terms of cost and reliability. In this study, the specifications of planetary gears are calculated using a self-developed gear design program. The actual gear bending and compressive stresses of the planetary gear system were analyzed using the Lewes and Hertz equation. Additionally, the calculated specifications of the complex planetary gears were verified by evaluating the results from the Stress - No. of cycles curves of gears.

효과적인 지식확장을 위한 LOD 클라우드에서의 변화수용적 심층검색

김광민(Kwangmin Kim),손용락(Yonglak Sohn) 한국지능정보시스템학회 2018 지능정보연구 Vol.24 No.2

본 연구는 시멘틱 웹의 실질적 구현체인 LOD 클라우드에서 연결정책을 활용함으로써 LOD들간 연결을 효과적으로 제공하고 LOD의 변경된 내용을 검색결과에 빠짐없이 반영할 수 있는 방안을 제시한다. 현재 LOD 클라우드에서는 개체간 연결은 <owl:sameAs>를 이용하여 개체들이 동일함을 명시적으로 기술하는 방식으로 이루어져 있다. 하지만, 이러한 명시적 연결방식은 LOD 클라우드 규모의 방대함에도 불구하고 개체간 동일성을 개체단위에서 파악하여야 하는 어려움이 있으며 주기적으로 LOD에 추가하여야 함에 따라 검색 시 개체들이 누락되는 한계가 있다. 이를 극복하기 위하여 본 연구에서는 명시적 연결을 생성하는 대신 LOD별로 연결하고자 하는 LOD와의 연결정책을 수립하여 LOD와 함께 공개하는 방식을 제안한다. 연결정책을 활용함으로써 연결하여야 할 동일개체를 검색시점에서 파악할 수 있으므로 추가되었던 개체들을 누락됨 없이 검색결과에 포함시킬 수 있고 LOD 클라우드에서의 연결성도 효과적으로 확충할 수 있다. 확충된 연결성은 정보의 지능적 처리의 선행과정인 지식확장의 근간이 된다. 연결정책은 연결하고자 하는 소스와 타겟 LOD의 주어 개체들간의 동일성을 평가하는데 도움이 되는 술어 쌍을 명세하는 방식으로 수립하며 검색 시 이러한 술어쌍에 대응하는 RDF 트리플을 검색하고 이들의 목적어들이 충분히 동일한 것인가를 평가하여 주어개체들의 동일수준을 판단한다. 본 연구에서는 이러한 연결정책을 이용하여 여러 LOD들을 심층적으로 검색하는 시스템을 구현하였다. 검색과정에서는 기존 명시적 연결들도 함께 활용하도록 구현하였다. 검색시스템에 대한 실험은 DBpedia의 주요 LOD들을 대상으로 진행하였다. 실험결과 연결대상 개체들의 목적어들이 0.8 ~ 0.9의 유사수준을 가지는 경우 적정한 확장성을 가지고 충분히 신뢰적인 개체들을 적절하게 포함하는 것으로 확인하였다. 또한, 개체들은 8개 이상의 동일연결을 제공하여야 검색결과가 신뢰적으로 활용될 수 있을 것으로 파악되었다. LOD(Linked Open Data) cloud is a practical implementation of semantic web. We suggested a new method that provides identity links conveniently in LOD cloud. It also allows changes in LOD to be reflected to searching results without any omissions. LOD provides detail descriptions of entities to public in RDF triple form. RDF triple is composed of subject, predicates, and objects and presents detail description for an entity. Links in LOD cloud, named identity links, are realized by asserting entities of different RDF triples to be identical. Currently, the identity link is provided with creating a link triple explicitly in which <owl:sameAs> associates its subject and object with source and target entities. Link triples are appended to LOD. With identity links, a knowledge achieves from an LOD can be expanded with different knowledge from different LODs. The goal of LOD cloud is providing opportunity of knowledge expansion to users. Appending link triples to LOD, however, has serious difficulties in discovering identity links between entities one by one notwithstanding the enormous scale of LOD. Newly added entities cannot be reflected to searching results until identity links heading for them are serialized and published to LOD cloud. Instead of creating enormous identity links, we propose LOD to prepare its own link policy. The link policy specifies a set of target LODs to link and constraints necessary to discover identity links to entities on target LODs. On searching, it becomes possible to access newly added entities and reflect them to searching results without any omissions by referencing the link policies. Link policy specifies a set of predicate pairs for discovering identity between associated entities in source and target LODs. For the link policy specification, we have suggested a set of vocabularies that conform to RDFS and OWL. Identity between entities is evaluated in accordance with a similarity of the source and the target entities’ objects which have been associated with the predicates’ pair in the link policy. We implemented a system “Change Acceptable In-Depth Searching System(CAIDS)”. With CAIDS, user’s searching request starts from depth_0 LOD, i.e. surface searching. Referencing the link policies of LODs, CAIDS proceeds in-depth searching, next LODs of next depths. To supplement identity links derived from the link policies, CAIDS uses explicit link triples as well. Following the identity links, CAIDS’s in-depth searching progresses. Content of an entity obtained from depth_0 LOD expands with the contents of entities of other LODs which have been discovered to be identical to depth_0 LOD entity. Expanding content of depth_0 LOD entity without user’s cognition of such other LODs is the implementation of knowledge expansion. It is the goal of LOD cloud. The more identity links in LOD cloud, the wider content expansions in LOD cloud. We have suggested a new way to create identity links abundantly and supply them to LOD cloud. Experiments on CAIDS performed against DBpedia LODs of Korea, France, Italy, Spain, and Portugal. They present that CAIDS provides appropriate expansion ratio and inclusion ratio as long as degree of similarity between source and target objects is 0.8 ~ 0.9. Expansion ratio, for each depth, depicts the ratio of the entities discovered at the depth to the entities of depth_0 LOD. For each depth, inclusion ratio illustrates the ratio of the entities discovered only with explicit links to the entities discovered only with link policies. In cases of similarity degrees with under 0.8, expansion becomes excessive and thus contents become distorted. Similarity degree of 0.8 ~ 0.9 provides appropriate amount of RDF triples searched as well. Experiments have evaluated confidence degree of contents which have been expanded in accordance with in-depth searching. Confidence degree of content is directly coupled with identity ratio of an entity, which means the degree of identit