• 천문학회보
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• 제36권1호
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• pp.58.1-58.1
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• 2011

We present elemental abundances of 95 blue compact dwarf galaxies (BCDs) at z=0.2~0.35 using the Sloan Digital Sky Survey (SDSS) DR7. We derived element abundances using Te method. We found that nitrogen abundance of merging BCDs are more enriched than normal BCDs by fast rotating young massive star. On the other hand, neon and oxygen abundances for merging BCDs are slightly lower than the normal BCDs. This might be result from the dilution by metal-poor gas infall during the interaction. This means that merging BCDs undergone star formation event for a long time than normal BCDs and we trying to explain using STARLIGHT code and various star formation rates (SFRs) ratios. At a result, merging BCDs have older stellar population (>10 Myr) more than normal BCDs and have clear distinction in elements abundances versus Ha/UV diagram. We also discuss the characteristics of post merger candidate using FUV to NUV ratios.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.79-80
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• 2007

A high performance organic phototransistor with dynamic range of 120 dB is demonstrated by employing soluble pentacene as a photo-sensing layer. The organic phototransistor used suspended source/drain (SSD) electrode structure, which provides a dark current level of ${\sim}10^{-14}$ A at positive gate bias. Under a steady-state illumination, the organic phototransistor exhibited a current modulation of $10^6$ compared to dark to give a dynamic range of 120 dB. These results suggest that the organic phototransistor based on TIPS pentacene can be a new premising candidate for low-cost and high-performance photo-sensing element for digital imaging applications.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.739-739
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• 2005

In the conventional AF lens actuating system the VCM actuator is used. However due to the actuating mechanism, the VCM actuator has disadvantage in miniaturizing which is essential to the actuator for the mobile device. Therefore novel type actuator is required and the one of the candidate is actuator using electoractive polymer (EAP). The EAP actuator is one of the attractive smart materials that is light and can be easily fabricated with low cost. This paper proposes an AF lens actuator for mobile phone using dielectric elastomer. The proposed actuator was designed and analyzed using finite element method. The designed actuator is verified by experiment and the position control algorithm is applied.

• Journal of Information Processing Systems
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• 제17권5호
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• pp.960-971
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• 2021

As the era of the 4th Industrial Revolution enters, the importance of software safety is increasing, but related systematic educational curriculum and trained professional engineers are insufficient. The purpose of this research is to propose the high priority elements for the software safety education program through needs analysis. For this purpose, 74 candidate elements of software safety education program were derived through contents analysis of literature and nominal group technique (NGT) process with five software safety professionals from various industries in South Korea. Targeting potential education participants including industrial workers and students, an on-line survey was conducted to measure the current and required level of each element. Using descriptive statistics, t-test, Borich needs assessment and Locus for focus model, 16 high priority elements were derived for software safety education program. Based on the results, suggestions were made to develop a more effective education program for software safety education.

• International Journal of Computer Science & Network Security
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• 제21권12호
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• pp.75-80
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• 2021

In this paper, a dual-band Koch Snowflake antenna is proposed for wireless communication systems. Fractal geometry, CPW-feed and stepped ground planes are used to improve the impedance bandwidth. By properly introducing a hexagonal split-ring slot to radiating element, a lower frequency band is generated. The proposed structure is fabricated and tested. Experiment results exhibit dual-band of 0.73-0.98 GHZ and 1.6-3.1 GHz which makes this antenna suitable candidate for GSM900, GSM1800, UTMS2100, Wi-Fi 2400 and LTE2600 bands. In addition, a good radiation pattern, a satisfactory peak gain and a radiation efficiency, which reaches 95%, are achieved.

• Smart Structures and Systems
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• 제21권4호
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• pp.407-420
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• 2018

In structural health monitoring, it is meaningful to comprehensively utilize accelerometers and strain gauges to obtain the modal information of a structure. In this paper, a modal estimation theory is proposed, in which the displacement modes of the locations without accelerometers can be estimated by the strain modes of selected strain gauge measurements. A two-stage sensor placement method, in which strain gauges are placed together with triaxial accelerometers to obtain more structural displacement mode information, is proposed. In stage one, the initial accelerometer locations are determined through the combined use of the modal assurance criterion and the redundancy information. Due to various practical factors, however, accelerometers cannot be placed at some of the initial accelerometer locations; the displacement mode information of these locations are still in need and the locations without accelerometers are defined as estimated locations. In stage two, the displacement modes of the estimated locations are estimated based on the strain modes of the strain gauge locations, and the quality of the estimation is seen as a criterion to guide the selection of the strain gauge locations. Instead of simply placing a strain gauge at the midpoint of each beam element, the influence of different candidate strain gauge positions on the estimation of displacement modes is also studied. Finally, the modal assurance criterion is utilized to evaluate the performance of the obtained multitype sensor placement. A bridge benchmark structure is used for a numerical investigation to demonstrate the effectiveness of the proposed multitype sensor placement method.

• Journal of the Korean Data and Information Science Society
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• 제27권6호
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• pp.1525-1536
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• 2016

학군장교 (ROTC)는 대학에 재학 중인 우수 학생들을 선발하여 2년간 군사교육을 실시하고 졸업과 동시에 장교로 임관시켜 군의 초급 지휘자로 활용하는 제도로서 규모나 역할로 봤을 때 우리나라의 군과 사회에서 차지하는 비중이 매우 크다. 따라서 ROTC 출신 초급장교들의 리더십을 향상시켜 우리나라 군의 무형 전투력을 성장시키는 것이 매우 중요하다. 본 연구의 목적은 학군장교 양성교육 프로그램이 학군장교 리더십을 향상시키기 위해 적절한 교육을 제공하고 있는지 파악하고 개선방안을 제시하는 데 있다. 먼저 학군장교 교육 프로그램을 크게 세 분야로 나누어 1, 2차 설문조사를 실시한 뒤, 카이제곱 검정 (chi-square test), 분산분석 (ANOVA), 던컨의 다중검정 (Duncan's multiple range test) 등의 통계분석 방법들을 이용하여 교육프로그램에 직간접적으로 관련된 조사대상자들의 교육에 대한 실태 및 인식을 비교 분석한다. 또한 다중회귀분석 (multiple regression analysis)을 이용하여 학군후보생 리더십의 기본요소인 육군리더의 3대자질 형성에 영향을 미치는 세부요소들을 분석한다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2006년도 춘계 종합학술대회 논문집
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• pp.140-143
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• 2006

본 논문에서는 최상급 질의에 대한 정답을 추출하는 질의-응답시스템에 대해 기술한다. 최상급 질의란 "가장", "제일", "처음", "최고의", "최대의", "최소의", "최초로", "최초의" 등의 최상급 단서 어휘를 포함하고 있는 질의를 말한다. 최상급 질의는 4가지 주요 성분-최상급 단서 어휘, 정답유형, 지역정보, 용언-과 기타 문장 성분으로 구성된다. 이 중 최상급 단서 어휘는 자신이 수식하는 용언을 반드시 필요로 하느냐에 따라 두 가지 유형으로 나뉘며, 이는 정답 추출을 위한 필수요소를 결정하는 기준이 된다. 모든 최상급 질의에 대해 최상급 단서 어휘, 정답유형, 지역정보는 정답을 추출하기 위한 필수요소이지만, 용언은 최상급 단서 어휘의 유형에 따라 필수요소로 결정된다. 본 논문의 시스템은 최상급 질의 분석을 통하여 정답 추출을 위한 필수요소를 찾고, 이를 이용하여 후보 문서와 후보 문장을 검색한 후, 정답을 추출한다. 실험 결과 최상급 질의에 대한 높은 정확률과 재현율을 보였다.

• Smart Structures and Systems
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• 제26권3호
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• pp.291-309
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• 2020

To study oceanic and meteorological problems related to climate change, Korea has been operating several ocean research stations (ORSs). In 2011, the Gageocho ORS was attacked by Typhoon Muifa, and its structural members and several observation devices were severely damaged. After this event, the Gageocho ORS was rehabilitated with 5 m height to account for 100-yr extreme wave height, and the vibration measurement system was equipped to monitor the structural vibrational characteristics including natural frequencies and modal damping ratios. In this study, a mass reallocation method is presented for structural model updating of the Gageocho ORS based on the experimentally identified natural frequencies. A preliminary finite element (FE) model was constructed based on design drawings, and several of the candidate baseline FE models were manually built, taking into account the different structural conditions such as corroded thickness. Among these candidate baseline FE models, the most reasonable baseline FE model was selected by comparing the differences between the identified and calculated natural frequencies; the most suitable baseline FE model was updated based on the identified modal properties, and by using the pattern search method, which is one of direct search optimization methods. The mass reallocation method is newly proposed as a means to determine the equivalent mass quantities along the height and in a floor. It was found that the natural frequencies calculated based on the updated FE model was very close to the identified natural frequencies. In conclusion, it is expected that these results, which were obtained by updating a baseline FE model, can be useful for establishing the reference database for jacket-type offshore structures, and assessing the structural integrity of the Gageocho ORS.

• 터널과지하공간
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• 제18권2호
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• pp.134-148
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• 2008

암반의 초기응력 상태는 방사성 폐기물 지층 처분장의 적합성을 판단하는데 중요한 요소이다. 본 연구에서는 3차원 개별요소법을 이용하여 스웨덴 방사성 폐기물 처분장 후보지 중 하나인 오스카샴 지역에서 대규모 변형대가 초기응력에 미치는 영향을 살펴보았다. 수치해석에서는 부지조사 과정에서 확인된 변형대를 모델에 포함시켰으며 원거리 지각응력을 경계조건으로 사용하였다. 현지 암반에서 관찰되는 초기응력값의 변화 양상이 수치해석에서도 재현이 됨으로써 수치해석이 암반의 초기응력상태를 이해하는데 유용하게 쓰일 수 있음을 확인하였다. 수치해석을 통한 예측값과 초기응력 측정값과의 차이는 측정된 자료의 양호한 정도, 지질모델 및 변형대의 물성치의 불확실성 등에 기인하는 것으로 생각된다.