• Journal of Power Electronics
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• 제13권4호
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• pp.679-691
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• 2013

High-power electromagnetic transmitter power supplies are an important part of deep geophysical exploration equipment. This is especially true in complex environments, where the ability to produce a highly accurate and stable output and safety through redundancy have become the key issues in the design of high-power electromagnetic transmitter power supplies. To solve these issues, a high-frequency switching power cascade based emission power supply is designed. By combining the circuit averaged model and the equivalent controlled source method, a modular mathematical model is established with the on-state loss and transformer induction loss being taken into account. A triple-loop control including an inner current loop, an outer voltage loop and a load current forward feedback, and a digitalized voltage/current sharing control method are proposed for the realization of the rapid, stable and highly accurate output of the system. By using a new algorithm referred to as GAPSO, which integrates a genetic algorithm and a particle swarm algorithm, the parameters of the controller are tuned. A multi-module cascade helps to achieve system redundancy. A simulation analysis of the open-loop system proves the accuracy of the established system and provides a better reflection of the characteristics of the power supply. A parameter tuning simulation proves the effectiveness of the GAPSO algorithm. A closed-loop simulation of the system and field geological exploration experiments demonstrate the effectiveness of the control method. This ensures both the system's excellent stability and the output's accuracy. It also ensures the accuracy of the established mathematical model as well as its ability to meet the requirements of practical field deep exploration.

• Human Ecology Research
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• 제60권4호
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• pp.609-623
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• 2022

As human life and welfare become more valued in the Fourth Industrial Revolution era, the role and mission of human ecology are expanding. Therefore, a career exploration and education program for high school students covering all the academic fields of human ecology may be necessary. To investigate what would be needed to develop such a program, a focus group interview (FGI) targeting experts within the same field and a survey targeting high school students were conducted. As a result of the FGI, a total of 3 categories and 7 subcategories were identified. The three categories included "human ecology and high school education," "human ecology and career choices," and "education program development and management in human ecology." The results of the high schoolers' survey showed that they had a moderate level of awareness about careers related to human ecology majors, but their interests and known information about human ecology programs in universities were low. Within the sub-content of each major, the contents with the highest educational needs were fashion product management, nutrition by disease, housing market analysis, personal financial management, and children's rights and welfare. If a career exploration and education program is implemented in the future, the most preferred type is a mentoring program by professors, students, and graduates in the field of human ecology. In conclusion, it is necessary to develop and implement an integrative education program about human ecology majors based on the educational needs of high school students.

• 천문학논총
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• 제27권4호
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• pp.145-146
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• 2012

We present the results from B-, R-, I-, J- and H-band observations of the NEP-Wide survey field. The NEP-Wide survey is an AKARI survey of the North Ecliptic Pole covering ~ 5 square degrees area. Our optical/NIR imaging supports the AKARI IR imaging data by providing a crucial coverage in the optical/NIR. The optical data were obtained in 2007 using the 1.5 m telescope and SNUCAM at Maidanak Observatory, Uzbekistan. The NIR data were obtained in 2008 with FLAMINGOS on the KPNO 2.1 m telescope. We used IRAF, SExtractor, SCAMP, and SWarp for reducing the raw data, I-band fringe pattern removal, astrometry, standard photometry calibration, and source detection. Our optical-NIR data reach the depths of B ~ 23.4, R ~ 23.1, I ~ 22.3, J ~ 21.05, and H ~ 20.64 AB mag at 5-sigma. Here, we present the astrometric accuracy, galaxy number counts, completeness, and reliability, as well as redshift tracks of some normal galaxies and quasars on the B - R vs. R - I color-color diagram. The photometric data are being used for identifying optical counterparts of the IR data provided by AKARI, studying their SEDs, and selecting interesting objects for spectroscopic follow-up studies.

• 천문학회보
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• 제42권2호
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• pp.78.1-78.1
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• 2017

We present a noble method to determine BH mass of many AGNs directly through reverberation mapping using a small telescope with wide-field of view. In 2017 August we installed five medium-band filters to a 0.25m diameter $5deg^2$ FOV telescope at the McDonald observatory. The width of these filters (FWHM ~ 50nm) are matched to the broad line width of type-1 AGNs at various redshifts. From recently obtained data, about r ~ 19 magnitude AGNs can be detected in line component with 150s exposure. With this magnitude limit, about 20~30 AGNs can be studied in one field. We plan to carry out at one day cadence observation over 20~30 fields, enabling us to monitor up to ~1000 AGNs over a wide range of variability. This poster presents out plan and early results from test observation.

• 지구물리와물리탐사
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• 제6권2호
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• pp.101-107
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• 2003

프레넬 볼륨을 이용하는 B차원 탄성파 주시 토모그래피 기법을 개발하고 수치자료를 이용하여 알고리즘의 타당성을 검증하였다. 3차원 주시 토모그래피 기법의 현장자료에의 적용성을 고찰하고자 시추공 간 탄성파 현장자료에 대한 주파수 특성 및 송수신 배열 커버리지를 검토하여 약 8m의 분해능의 3차원 입방체의 속도정보를 도출하였다. 3차원 속도분포를 기존의 2차원 토모그램과 비교하였을 때 두 결과가 잘 일치함을 확인함으로써 3차원 토모그래피 알고리즘의 현장 적용성을 확인하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2006년도 공동학술대회 논문집
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• pp.109-112
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• 2006

기존 상용 전기탐사장비의 한계는 간척지 갯벌 등 해성퇴적층 하부지반조사 적용이 매우 힘들거나, 불가능한 것으로 인지되어 왔다. 최근 전 세계적으로 해저면 또는 연안지역환경 전기탐사 필요성이 대두됨에 따라 자체개발 발전기 전원 5 Ampere 대전류 송신 전기탐사 현장적용이 광양만에서 확인된다. 항만관련 기반시설 연안투자는 지속 확대될 것으로 기존 탐사방법 지반조사에서 탈피하여 항만 교량, 해저터널, 해저 가스 층 등의 효과적 적용 가능성이 기대된다. 한편 조석변화를 고려한 대전류 전기 비저항탐사를 수위별로 시간대 측정하여 연약구역 효과를 비교 시도하였다. 대전류 송신은 탐사전선저항 길이를 고려한 덜 무거운 케이블 선택 설계가 현장야업 시 중요하다.

• 지구물리와물리탐사
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• 제2권4호
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• pp.209-214
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• 1999

트렌치를 이용하여 다성분 탄성파 탐사에 필요한 횡파를 발생시키는 현장 실험을 2개소에서 실시하였다. 실험결과 1개소에서는 트렌치 연장 방향에 직각 방향으로 양호하게 분극된 횡파를 얻을 수 있었으며 다른 한 곳에서는 횡파 생성에 실패하였다. 시추공 내에 설치한 3성분 지오폰 기록을 필터링, 에너지 balancing, 수평 및 수직 성분 자료의 가$\cdot$감산 등 전처리 과정을 거쳐 P파와 S파를 분리하였고, S파의 직접파 이벤트를 분석하여 매질의 이방성을 관측할 수 있었다. 분석결과에 의하면 $SH_{max}$ 방향이 남북 방향이었으며 이는 시추코어에서 관찰된 파쇄대 절리 방향과 같다는 사실을 확인하였다.

• 지구물리와물리탐사
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• 제6권4호
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• pp.187-194
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• 2003

다중 주파수 소형루프 전자탐사법은 가탐심도의 한계에도 불구하고 조사가 신속하고 비용이 저렴하다는 장점을 가지고 있다. 따라서 이 방법은 각종 지반조사 및 환경문제의 해결을 위하여 널리 사용되고 있다. 본 논문에서는 소형루프 전자탐사 자료를 이용하여 지하의 2차원 영상화 기법을 개발하였다. 지하의 전기비저항 분포를 영상화하기 위하여 주파수 수직탐사 자료에 대한 1차원 역산법을 사용하였다. 이론 자료에 대한 역산결과 지하의 전기비저항 구조에 대한 양호한 영상을 구현할 수 있었다. 또한 강원도 춘천에 위치한 농장에서 획득한 현장자료를 사용하여 전기비저항 2차원 단면을 작성하고, 이를 쌍극자 배열 전기비저항 탐사 결과와 비교, 검토하였다.

• Geosystem Engineering
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• 제21권6호
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• pp.318-325
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• 2018

Eight tight sandstone reservoir samples from $He_8$ and $Shan_1$ Formations of the Sulige Gas field were selected to perform gas-water micro-displacement experiment based on authentic sandstone micro-model. The gas pressure-relief experiment was proposed for the first time to simulate the pressure change and gas-water percolation characteristics in the process of gas exploitation. The experiment results show that: (1) In the process of gas accumulation, the gas preferentially flows into the well-connected pores and throats with large radius, but rarely flows into the area without pores and throats. (2) Under sufficient gas drive, the water in pores and throats usually exists in the forms of 'thin water film', 'thick water film', and 'water column', but under insufficient gas drive, gas fails to flow into new pathways in time, so that the reservoirs with large pores and throats are high in water cut. (3) Under the same water saturation, the reservoirs with better petrophysical properties has higher gas recovery factor within unit time. Under the same petrophysical conditions, the reservoirs with lower water saturation show higher gas recovery factor within unit time. The higher the permeability, the stronger the liquid carrying capacity of reservoirs.

• International Journal of Control, Automation, and Systems
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• 제5권5호
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• pp.539-546
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• 2007

The important field of research in ship operation is related to the high efficiency of transportation, the convenience of maneuvering ships and the safety of navigation. For these purposes, many intelligent technologies for ship automation have been required and studied. In this paper, we propose an intelligent voice instruction-based learning (VIBL) method and discuss the building of a ship's steering control system based on this method. The VIBL system concretely consists of two functions: a text conversion function where an instructor's inputted voice is recognized and converted to text, and a linguistic instruction based learning function where the text instruction is understood through a searching process of given meaning elements. As a study method, the fuzzy theory is adopted to build maneuvering models of steersmen and then the existing LIBL is improved and combined with the voice recognition technology to propose the VIBL. The ship steering control system combined with VIBL is tested in a ship maneuvering simulator and its validity is shown.