아날로그 응용을 위한 DWFG MOSFET의 매크로 모델 및 연산증폭기 설계

하지훈,백기주,이대환,나기열,김영석,Ha, Ji-Hoon,Baek, Ki-Ju,Lee, Dae-Hwan,Na, Kee-Yeol,Kim, Yeong-Seuk 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.8

In this paper, a simple macro model of n-channel MOSFET with dual workfunction gate (DWFG) structure is proposed. The DWFG MOSFET has higher transconductance and lower drain conductance than conventional MOSFET. Thus analog circuit design using the DWFG MOSFET can improve circuit characteristics. Currently, device models of the DWFG MOSFET are insufficient, so simple series connected two MOSFET model is proposed. In addition, a two stage operational amplifier using the proposed DWFG MOSFET macro model is designed to verify the model.

연구원의 연구윤리강령 모형에 대한 통계적 분석

하지훈(Ji-Hoon Ha) 한국산업경영시스템학회 2009 한국산업경영시스템학회지 Vol.32 No.4

This study is designed to prove the role and effect of ethics codes in professional societies, especially for scientists and engineers working in R&D project groups The hypotheses of influence on ethical conduct within the sample groups are tested and analyzed by statistical methods Results show that the age of researchers and the integrity factor among the ethical conduct factors have significant influence on ethical conduct of research groups The regression model of the ethical conduct factors also indicates a meaningful reference in an application or development of new ethics code in research organizations

핵심역량과 과학과 교과역량에 대한 초등 교사의 인식 분석

하지훈 ( Ha Ji-hoon ),신영준 ( Shin Youngjoon ) 한국초등과학교육학회 2016 초등과학교육 Vol.35 No.4

The purpose of this study was getting the information for successful application to the national curriculum and students` core competencies enhancement, through investigation about competencies discussed in 2015 revised national curriculum development process and analysis about perception of 150 elementary school teachers in study. The results were as follows : Communication skill is considered to be the most important. Thinking ability what has been important traditionally is the middle of the rankings. Elementary school teachers think that a competency is specific to a subject. From this point of view, Creative/Scientific Problem-Solving Ability is the most important in science. They think that the enhancing of the ability of inquiry performance is highlighted in current science class. On elementary school teachers` awareness, inquiry model is the most effective in enhancing of scientific thinking and the ability of inquiry performance. And STS instruction model is in the other. PBL learning model and experimental inquiry model is the most effective in enhancing a competency has the highest feasibility like scientific thinking or the ability of inquiry performance.

한국 제천 감초(Glycyrrhiza uralensis Fisher)의 추출 조건별 추출물의 항산화 및 항균 활성 평가

하지훈 ( Ji Hoon Ha ),정윤주 ( Yoon Ju Jeong ),성준섭 ( Joon Seob Seong ),김경미 ( Kyoung Mi Kim ),김아영 ( A Young Kim ),부민민 ( Min Min Fu ),서지영 ( Ji Young Suh ),이난희 ( Nan Hee Lee ),박진오 ( Jino Park ),박수남 ( Soo Nam P 대한화장품학회 2015 대한화장품학회지 Vol.41 No.4

본 연구는 한국 제천에서 재배된 감초(Glycyrrhiza uralensis Fisher, G. uralensis)를 대상으로 추출 조건(85% 에탄올, 추출 온도 및 시간)별로 추출한 추출물에 대하여 항산화 활성 및 항균 활성을 측정하고 이로부터 최적의 추출 조건을 선정하여 감초 추출물을 화장품 원료로 개발하기 위한 제조 공정에 활용하고자 하였다. 실험에 사용한 시료는, 각 추출 조건에서 얻어진 추출물을 농축하여 분말로 한 시료(시료-1)와 추출물을 농축하지 않고 추출물 원액을 그대로 사용한 시료(시료-2)이다. 항산화 활성은 라디칼 소거활성, 총항산화능, 활성산소로 유도된 세포손상에서 세포보호효과를 측정하였다. 항균 활성은 피부 상재균에 대한 최소저해농도를 측정하였다. 1,1,-Diphenyl-2-picrylhydrazyl를 이용한 라디칼 소거활성에서, 시료-1은 100 μg/mL에서 추출시간이 6 h일 때가 12 h일 때보다 약 10% 정도 더 큰 라디칼 소거활성을 나타냈다. 반면에 시료-2의 라디칼 소거활성은 추출 시간에 따른 유의적 차이를 나타내지 않았다. 한편 동일 온도에서 12 h 추출한 추출물의 수율은 6 h 추출한 경우의 수율보다 2.6배 더 컸다. 하지만 총 플라보노이드 함량은 1.1배 정도 더 크게 나타났다. 따라서 추출 시간이 길어도 총플라보노이드 함량은 거의 증가하지 않았음을 보여준다. 추출 조건별 감초 추출물의 라디칼 소거활성, 총항산화능 및 세포보호효과가 추출물의 수율을 반영한 것이 아니라 추출물 중에 함유된 총플라보노이드 함량에 의존함을 나타내고 있다. 피부 상재균에 대한 항균 활성은 추출 조건별 동일 농도(시료-1)에서 측정했을 때, 세 균주(S. aureus, B. subtilis, P. acnes)에 대해 25 및 40 ℃에서 추출된 감초추출물(156 μg/mL)은 methyl paraben (2,500 μg/mL)보다 약 16배 정도로 매우 큰 항균 활성을 나타냈다. 결론적으로 항산화 활성 및 항균 활성이 큰 감초 추출물의 최적 추출 조건은 85% 에탄올로 40 ℃에서 6 h 추출한 추출물이 최적임을 확인할 수 있었다. 본 연구 결과, 화장품에 항산화 활성 및 항균 활성이 큰 감초 추출물을 원료화하기 위해서는 추출 조건별 추출물의 수율, 활성 성분의 수율, 추출물의 농도별 활성 평가와 추출 수율이 반영된 추출물 원액 자체의 활성을 종합 평가해서 추출 조건을 선정해서 원료의 제조 공정에 반영하는 것이 중요함을 시사한다. This study was carried out to evaluate the antioxidant and antibacterial activities of Glycyrriza uralensis Fisher (Jecheon, Korea) extracts obtained by various extraction conditions (85% ethanol, heating temperatures and times), and to establish the optimal extraction condition of G. uralensis for the application as cosmetic ingredients. The extracts obtained under different conditions were concentrated and made in the powdered (sample-1) and were the crude extract solutions without concentration (sample-2). The antioxidant effects were determined by free radical scavenging activity (FSC50), ROS scavenging activity (OSC50), and cellular protective effects. Antibacterial activity was determined by minimum inhibitory concentration (MIC) on human skin flora. DPPH free radical scavenging activity of sample-1 (100 μg/mL) was 10% higher in group extracted for 6 h than 12 h, but sample-2 didn’t show any significant differences. The extraction yield extracted with same temperature for 12 h was 2.6 times higher than 6 h, but total flavonoid content was 1.1 times higher. These results indicated that total flavonoid content hardly increased with increasing extraction time. Free radical scavenging activity, ROS scavenging activity and cellular protective effects were not dependent on the yield of extraction, but total flavonoid content of extraction. Antibacterial activity on three skin flora (S. aureus, B. subtilis, P. acnes)of sample-1 in different extraction conditions were evaluated on same concentration, and the group extracted at 25 and 40 ℃ showed 16 times higher than methyl paraben (2,500 μg/mL). In conclusion, 85% ethanol extracts of G. uralensis extracted at 40 ℃ for 6 h showed the highest antioxidant and antibacterial activity. These results indicate that the extraction condition is important to be optimized by comprehensive evaluation of extraction yield with various conditions, yield of active component, and activity test with concentrations, and activity of 100% extract, for manufacturing process of products.

초등과학교과서 전자저작물에 탑재된 멀티미디어 자료 분석

하지훈 ( Ji Hoon Ha ),신영준 ( Young Joon Shin ) 한국초등과학교육학회 2016 초등과학교육 Vol.35 No.1

The purpose of this paper was to analyze the kinds and roles of multimedia materials in E-works that are distributed with elementary textbooks (3~6 grade) of the 2009 revised science curriculum. Five criteria (forms, goals, key competencies, inquiry process, running time) were set for this. The sample of the paper was the 784 multimedia materials in E-works of elementary science textbooks (3~6 grade) of the 2009 revised science curriculum. The results of the multimedia materials analysis are as follows: The result of the material forms of multimedia is that the form of highest ratio is text type. But all forms were used evenly in E-work. 56.2% of the multimedia materials are for “inquiry” in the goal criteria, and 65.0% of the multimedia materials are related to “science inquiry” in the key competencies criteria. Two facts indicate many multimedia is used to develop students’ inquiry ability. However the ratio of multimedia materials in motivation step is higher than that in inquiry activity step. In analysis of running time, the ratio of “under 5 min” multimedia materials is the highest. But, the ratio of 5~10 min multimedia materials in inquiry part is higher than that in motivation part in The Chi-square test between “running time” and “parts” that consist of motivation part and inquiry part. Through the analysis of module and the categorizing the multimedia materials, we found that the multimedia materials play eleven roles in E-works that are distributed with elementary textbooks.

원산지별 감초추출물의 항산화활성 증가를 위한 효율적인 추출조건 탐색

하지훈 ( Ji Hoon Ha ),이혜미 ( Hye Mi Lee ),권순식 ( Soon Sik Kwon ),김해수 ( Hae Soo Kim ),김문진 ( Moon Jin Kim ),전소하 ( So Ha Jeon ),정유민 ( Yoo Min Jeong ),황준필 ( Jun Pil Hwang ),박종호 ( Jong-ho Park ),최영기 ( Yung-key 대한화장품학회 2013 대한화장품학회지 Vol.39 No.4

본 연구에서는 한국 및 중국산 감초(Glycyrrhiza uralensis), 그리고 우즈베키스탄산 감초(Glycyrrhiza glabra)를 대상으로 추출용매, 추출온도, 추출시간 등 추출조건별 추출물을 제조하고 이들 추출물들의 추출 수율과 항산화 활성을 비교하여 최적의 추출조건을 선정하였다. 항산화 활성 중 자유 라디칼(1,1-phenyl-2-pic-rylhydrazyl, DPPH) 소거활성은 85% 에탄올로 60 ℃에서 6 h 동안 추출한 조건에서 한국 감초로부터 얻은 추출물이 가장 높은 활성(46.05%)을 나타내었다. 루미놀 발광법을 이용한 추출물들의 총 항산화능 측정 실험과 피부 광노화에 중요한 ¹O₂으로 유도된 세포막 손상에 대한 추출물들의 세포 보호 효과를 측정한 실험 모두에서도 위의 조건에서 가장 높은 항산화 활성을 나타내었다. 특히, 한국 감초는 τ₅₀이 116.4 min으로 비교 물질인(+)-α-tocopherol (28.5 min)보다 약 4 배나 높은 세포 보호 효과를 나타내었으며, 추출 수율은 18.75%로 우즈베키스탄 및 중국 감초보다 각각 1.2 배 및 2.5 배의 추출 수율을 나타내었다. 따라서, 본 연구 결과는 항산화 소재로 화장품에 응용하기 위하여 감초로부터 추출물을 얻기 위한 최적의 조건은 85% 에탄올로 60 ℃에서 6시간 동안 추출하는 것임을 보여주었다. In this work, licorice extracts were prepared using various extraction conditions such as extraction solvent, temperature, and time from Glycyrrhiza uralensis (G. uralensis) produced in Korea and China and Glycyrrhiza glabra (G. glabra) in Uzbekistan. The optimum extraction condition was selected from the extraction yields and antioxidative activities of extracts. Korea licorice extracts showed the highest free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scav-enging activity (46.05%) under the extraction condition of 85% ethanol at 60 ℃ for 6 hours. The prominent ROS (reactive oxygen species) scavenging activity using luminol-dependent chemiluminescence assay and the cellular protective effect against ¹O₂ induced cellular membrane damage were also shown from the extracts obtained from the same condition. Especially, Korea G. uralensis extracts exhibited the higher prominent protective effect (τ₅₀ = 116.4 min) than (+)-α-tocopherol (τ₅₀ = 28.5 min) and the extraction yield of Korea licorice extract was 18.75%, which is 1.2 times and 2.5 times higher than that of Uzbekistan and China, respectively. These results indicate that the extraction condition of 85% ethanol at 60 ℃ for 6 hours is optimal to prepare licorice extracts, which can be applicable as antioxidative cosmetic materials.

초등 과학 교과서에 제시된 `생태계 속 생물의 역할`과 관련된 과학 용어 분석

하지훈 ( Ji-hoon Ha ) 韓國生物敎育學會 2017 생물교육 Vol.45 No.1

The purpose of this study was analyzing about scientific terms, producers, consumers, & decomposers, in the ecosystem chapter of elementary science textbook for confirming problems and finding solutions about the presentation forms and contents of them. The applied analysis framework consist of Form and Content, two aspects. The Form aspect has four categories (paragraph, subheading, term, font) and the Content aspect has tree categories (roleexplanation, example, scavenger). The results were as follows: In the results of the forms aspect analysis, the forms of presented term and font in Korean science textbook become more obvious in changes of curriculums. Foreign science textbooks have subheadings and paragraphs for each term, and they have more obvious presentation of term and more information than Korean science textbook. In the results of the contents aspect analysis, all science textbooks have the explanations of `energy roles in ecosystems` as the intension and the examples of organisms as the extension. In local science textbook analysis results, science textbook has gradually improved to present the intension of all terms and have more diverse examples. All foreign science textbooks have the contents about scavengers, but they have different viewpoints on scavengers. Korean science textbook, on the other hand, have no contents about scavenger. For this reason, the difficulty may lies in the classification of the scavengers like earthworm by presented explanations and examples in a current science textbook. Therefore there are needs of the developments of the effective presentation forms and the contents about scavengers.

RIA 기술을 이용한 웹 기반의 망 관제 서비스

하지훈(Ha Ji Hoon),김형수(Kim Hyung Soo),민경배(Min Kyeong Bae),정병덕(Byung Deok Chung) 한국통신학회 2009 한국통신학회 학술대회논문집 Vol.2009 No.11

연구논문 : 초등학생의 VARK 학습양식과 과학적 의사소통 능력의 관계

하지훈 ( Ji Hoon Ha ),신영준 ( Young Joon Shin ) 한국초등과학교육학회 2014 초등과학교육 Vol.33 No.4

The purpose of this study was to confirm correlation between elementary school students` VARK Learning styles test and Scientific Communication Skills through VARK questionnaire (version 7.3) for Youngers and Scientific Communication Skills Test. The subjects were 99 in 6th grade students of an elementary school located in Gyeonggi-do, Korea. The results of this study were as follows: 64% of the students had multiple learning styles, but only 36% of the students preferred a single mode of information presentation. Among students had a single mode preference, the aural (“A”) was the highest unimodal preference. Among “V(visual)” mode, “A” mode, “R(read/write)” mode, and “K(kinesthetic)” mode, “A” mode was the commonest learning mode which students had. In Scientific Communication Skills Test, students` overall average was 26.19p [scientific explanation type (11.85p), scientific insistence type (14.34p)]. Girls` scores were higher than boys in scientific explanation type, but not in scientific insistence type. The scores by communication forms were Text (5.67p), Number (6.87p), Table (6.15p), and Picture (7.49p). Girls` scores were higher than boys in Text and Picture forms but not in Number and Table forms. In result of correlation analysis (Spearman`s rho) between VARK Learning Styles and the types & forms of Scientific Communication Skills, there were common correlation in “Read/write (R) learning style- Scientific insistence type”, “Read/write (R) learning style-Grounds of Scientific insistence”, “Read/write (R) learning style- Description of Scientific explanation”, and “R learning style-Text form”.

플래시 메모리 기반의 DBMS를 위한 동적 블록 할당에 기반한 효율적인 로깅 방법

하지훈(Ji Hoon Ha),이기용(Ki Yong Lee),김명호(Myoung Ho Kim) 한국정보과학회 2009 정보과학회논문지 : 데이타베이스 Vol.36 No.5

플래시 메모리는 비휘발성이면서도 작고 가벼우며, 전력 소모가 적고 충격에 강하다는 장점 등으로 인해 휴대 기기를 포함한 다양한 기기의 저장매체로 사용되고 있다. 그러나 플래시 메모리는 하드디스크와는 달리 제자리 갱신이 불가능하고, 읽기 연산에 비해 쓰기 및 지우기 연산이 매우 느리기 때문에, 기존의 하드 디스크를 기반으로 설계된 데이터베이스 시스템은 플래시 메모리 상에서 최적의 성능을 내기 어렵다. 플래시 메모리 상에서 데이터베이스의 성능을 극대화하기 위해, 어떤 데이터에 변경이 발생하면 원래 위치의 데이터를 덮어쓰는 대신, 해당 데이터의 변경 사항에 대한 로그만을 다른 위치에 기록하는 방식들이 제안되었다. 본 논문에서는 플래시 메모리 기반의 데이터베이스 시스템을 위한 효율적인 로깅 방법을 제안한다. 제안하는 방법은 기존 방법들과 달리, 로그만을 저장하는 로그 블록들을 별도로 두고 데이터의 변경에 따라 발생하는 로그를 로그 블록들에 고르게 분포시킨다. 이를 통해 제안하는 방법은 페이지 쓰기 및 블록 지우기 연산의 횟수를 크게 감소시킬 수 있다. 합성 데이터와 TPC-C 벤치마크 데이터를 사용한 실험을 통해, 제안하는 방법은 기존의 방법에 비해 좋은 성능을 나타냄을 보였다. Flash memory becomes increasingly popular as data storage for various devices because of its versatile features such as non-volatility, light weight, low power consumption, and shock resistance. Flash memory, however, has some distinct characteristics that make today’s disk-based database technology unsuitable, such as no in-place update and the asymmetric speed of read and write operations. As a result, most traditional disk-based database systems may not provide the best attainable performance on flash memory. To maximize the database performance on flash memory, some approaches have been proposed where only the changes made to the database, i.e., logs, are written to another empty place that has been erased in advance. In this paper, we propose an efficient log management scheme for flash-based database systems. Unlike the previous approaches, the proposed approach stores logs in specially allocated blocks, called log blocks. By evenly distributing logs across log blocks, the proposed approach can significantly reduce the number of write and erase operations. Our performance evaluation shows that the proposed approaches can improve the overall system performance by reducing the number of write and erase operation compared to the previous ones.