• 천문학회지
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• 제34권1호
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• pp.9-15
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• 2001

We present the results of optical differential photometry of five blazars [PKS0219+428 (3C66A), PKS 0235+164 (AO 0235+16), H0414+019, PKS 0851+202 (OJ 287) and QSO 1807+698 (3C 371)] that were observed on 7 nights between November 05, 1997 and December 29, 1998, using the B and the V band filters. We have detected microvariations in four blazars (3C66A, AO 0235+16, H04l4+019, and OJ 287). In addition, the light curve of AO 0235+16 has displayed a mini-flare when the brightness of this source was decreasing. Night-to-night variations have also been detected in 3C66A, H04l4+019, and OJ 287. The results of our observations are discussed in the framework of accretion disk phenomena (magnetic flares or hot spots in accretion disks) and jet phenomena (plasma instabilities in jets).

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.31.1-31.1
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• 2008

While some observations in the geomagnetic tail region supported electrons could be accelerated by reconnection processes, we still need more observation data to confirm electron acceleration in this region. Because most acceleration processes accompany strong pitch angle diffusion, if the electrons were accelerated in this region, strong energetic electron precipitation should be observed near earth on aurora oval. Even though there are several low altitude satellites observing electron precipitation, intense and small scale precipitation events have not been identified successfully. In this presentation, we will show an observation of strong energetic electron precipitation that might be analyzed by relativistic electron acceleration in the confined region. This event was observed by low altitude Korean STSAT-1, where intense several hundred keV electron precipitation was seen simultaneously with 10 keV electrons during storm time. In addition, we observed large magnetic field fluctuations and an ionospheric plasma depletion with FUV aurora emissions. Our observation implies relativistic electrons can be generated in the small area where Fermi acceleration might work.

• 한국재료학회지
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• 제4권2호
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• pp.233-240
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• 1994

Pt/Co인공격자다층막($[Pt10.7\;{\AA}/Co2.8\;{\AA}]{\times}12$)의 자기특성 및 기록특성이 시료제작시의 조건 (sputtering gas압력, sputtering gas 종류, buffer층의 유무 및 etching)에 따라 어떻게 변화하는지를 알아보았다. Pt/Co다층막의 자기특성은 Tb-Fe-Co계 아몰퍼스재료와 거의 동등한 특성이 얻어졌으며 이다층막을 이용한 광자기디스크의 기록특성은 kerr회전각, 1.23도, 기록 power 특성, 36dB(레이저파장: 780nm)을 나타내어 Pt/Co다층막이 차세대광자기디스크용 재료로서의 실용화가능성을 보여주었다.

• 전기학회논문지
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• 제60권7호
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• pp.1444-1450
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• 2011

An analysis of the causes of railroad crossing accidents reveals that most train collision accidents that occur when safety crossing devices are functioning normally occur because vehicles either experience engine failure on the tracks or because drivers were not notified of the coming train, in which case they get trapped on the tracks when the crossing barriers descend. To prevent such an accident, obstacle detection device by using laser beams detecting the presence of obstacle and crossing bar direction controller by moving direction detection sensor using the Earth's magnetic field detection technology are used in the railroad crossing. Despite using the obstacles detector and crossing bar direction controller in the railroad crossing, the equipments for the railroad crossing does not prevent accidents completely. Therefore, this research has studied new method that can detect obstacles through image analyze and alternate existing equipments. There will be excellent effect to be preventing railroad crossing accident by developing a reliable and new obstacle detecting device.

• 한국정보통신학회논문지
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• 제11권10호
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• pp.1986-1991
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• 2007

본 논문에서 지구자기장을 측정하여 방위를 결정하는 자기 저항 소자의 경사각의 이상 현상에서 있어 예측할 수 없는 특성에 대해 불확실성에서의 추론을 통해 센서로서의 안정성을 확보하는데 그 목적이 있다. 따라서 퍼지 알고리즘을 적용하여 외부 환경 변화에 민감하게 변화하는 소자의 왜곡현상을 프로그래밍 적인 요소를 실험하여 센서의 왜율적인 요소에서 벗어남을 보인다. 나아가 소자의 고속, 고신뢰성을 갖는 응용에 사용할 수 있음을 보인다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.590-597
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• 2003

Processing and smelting of copper containing sulphide concentrates result in the accumulation of impurities into various process streams. All primary copper smelters and refineries around the world produce significant amounts of slag, dust, sludge, residues and others, which contain copper and precious metals. The recovery of these valuable metals is essential to the overall economics of the smelting process. Physical, chemical and mineralogical characterization of particular slag and Cottrell dusts from primary smelters and $Dor\'{e}$ furnace (TBRC) slag and Pressure Leached Anode slimes from a copper refinery have been carried out to understand the basic behind the recovery processes. Various process options have been evaluated and adapted for the treatment of slag from different smelting furnaces and Cottrell dusts as well as the intermediate products from copper refineries. Besides the hydro- or pyro-metallurgical treatments, the above mentioned physical separation options such as magnetic, gravity separation, flotation and precipitation flotation processes have been successfully identified and adapted as the possible process options to produce a Cu-rich or precious metal-rich concentrates for in-house recycling and other valued by-product for further treatment. The results of laboratory, pilot plant and production operations are presented, and incorporation of several alternative flowsheet is discussed in this paper.

• 한국지구과학회지
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• 제29권1호
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• pp.1-12
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• 2008

본 연구에서는 한반도 남동부의 의성분지 내에 위치하는 화산칼데라 지역을 대상으로 지구물리학적 연구를 수행하였다. 기존 연구들의 한계를 극복하기 위해 원격탐사를 통한 전체적인 구조 특성을 분석한 후에 정밀한 3차원 포텐셜 해석을 수행하는 기법을 적용하였다. 첫 번째 단계로, 수치지질도 및 DEM 자료와 인공위성 영상을 이용하여 대상 지역의 선구조를 분석하였다. 선구조 분석 결과는 선행 연구결과와 상당히 잘 부합되었고, 남-북 방향과 남동-북서방향이 가장 우세함을 보여주었다. 두 번째 단계로, 선구조 분석 결과를 고려하여 의성분지 전체 지역에서 조밀한 중력탐사 자료를 획득하였고 항공자력탐사 자료와의 복합 해석을 통해 광역적인 칼데라의 구조를 조사하였다. 파워 스펙트럼 기법을 이용한 분석 결과, 의성 분지 하부는 개략적으로 2개의 밀도 불연속면 이 존재하는 것으로 해석되었다. 첫 번째 불연속면의 심도는 약 1 km로 칼데라 지역 내에 존재하는 화산쇄설성 퇴적암의 심도나 화산칼데라의 ring vent 위치에서 관입하고 있는 관입암의 심도로 판단되며, 두 번째 심도는 약 3-5 km로 분지기반암의 심도와 관련 있는 것으로 추정된다. 또한 3차원 중력역산을 실시한 결과 남서쪽의 백악기 팔공산 화강암과 북동쪽의 불국사 관입암류에 의한 저밀도체가 나타나고, 화산칼데라 중앙부 부근에는 화산쇄설성 퇴적암류 또는 칼데라 형성 과정에서 침강된 상부의 퇴적층으로 해석된 퇴적층이 주변보다 낮은 밀도를 가지며 하부로 약 1.5 km까지 연장되어 있는 것으로 분석되었다. 그러나 포텐셜 자료는 그 특성상 수직 분해능이 양호하지 못하므로, 수직적인 발달 특성을 갖는 칼데라의 구조를 정확히 파악하기는 어렵다. 본 연구에서는 이런 한계점을 극복하기 위해서 동일 지역에서 이루어졌던 자기지전류 탐사 결과와 비교 분석하여 효과적인 해석을 수행하였다.

• 한국지구과학회지
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• 제39권6호
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• pp.519-532
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• 2018

우리는 오리온 분자운 복합체의 북부 필라멘트(이하 NF)에 대하여 $^{12}CO$ (J=1-0) 분자선의 자료를 이용하여 은하 평면이 분자의 운동과 운동학에 미치는 영향을 연구하였다. 6 m 서울대학교 전파망원경(Seoul Radio Astronomy Observatory, SRAO)을 이용하여 2arcmin 공간분해능으로 은하면으로부터 먼 순서로 NF1, NF2, NF3 세 곳을 총 270시간 동안 관측된 자료를 사용하였다. 은하면과 OMC NF는 $^{12}CO$ (J=2-1) 경우 3% 밀도에서, 티끌의 경우 9% 밝기 수준에서 자기장을 따라 서로 연결되어 있었다. $^{12}CO$ (J=1-0), $^{12}CO$ (J=2-1), 성간 티끌 관측결과를 비교해본 결과, 세 경우 모두 NF3에서는 고루 분포했지만, NF1과 NF2에서는 비교적 밀도가 높은 특정 영역에서만 함께 나타났다. NF는 단일 구조를 보였으며, NF1에서는 부분 수축 운동을, NF2에서는 하단에서 회전 운동이 나타났고, NF3에서는 유일하게 명확히 자기장에 연관된 나선형 회전이 보였다. 위치-속도 분석 결과, $^{12}CO$ (J=1-0)를 비롯한 물질들은 NF2와 NF3을 따라 은하면을 향하여 흐를 가능성이 있음을 확인할 수 있었다. 은하면을 향하여 물질이 흐르는 명백한 원인을 이번 연구결과에서 볼 수 없었지만 추후의 더 정교한 관측결과가 NF1과 NF2 상단부의 회전 운동을 확인 할 수 있겠다.

• 자원환경지질
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• 제12권2호
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• pp.95-104
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• 1979

The position of any point on the earth's surface can be. represented in the spherical coordinates by surface spherical harmonics. Since geomagnetic field is a function of position on the earth, it can be also expressed by spherical harmonic analysis as spherical harmonics of trigonometric series of $a_m({\theta})$ cos $m{\phi}$ and $b_m({\theta})$ sin $m{\phi}$. Coefficients of surface spherical harmonics, $a_m({\theta})$ and $b_m({\theta})$, can be drawn from the components of the geomagnetic field, declination and inclination, and vice versa. In this paper, components of geomagnetic field, declination and inclination in the Korean peninsula are obtained by spherical harmonic analysis using the Gauss coefficients calculated from the world-wide magnetic charts of 1960. These components correspond to the values of normal geomagnetic field having no disturbances of subsurface mass, structure, and so on. The vertical and total components offer the zero level for the interpretation of geomagnetic data obtained by magnetic measurement in the Korean peninsula. Using this zero level, magnetic anomaly map is obtained from the data of airborne magnetic. prospecting carried out during 1958 to 1960. The conclusions of this study are as follows; (1) The intensity of horizontal component of normal geomagnetic field in Korean peninsula ranges from $2{\times}10^4$ gammas to $2.45{\times}10^4$ gammas. It decreases about 500 with the increment of $1^{\circ}$ in latitude. Along the same. latitude, it increases 250 gammas with the increment of $1^{\circ}$ in longitude. (2) Intensity of vertical component ranges from $3.85{\times}10^4$ gammas to $5.15{\times}10^4$ gammas. It increases. about 1000 gammas with the increment of $1^{\circ}$ in latitude. Along the same latitude, it decreases. 150~240 gammas with the increment of $1^{\circ}$ in longitude. Decreasing rate is considerably larger in higher latitude than in lower latitude. (3) Total intensity ranges from $4.55{\times}10^4$ gammas to $5.15{\times}10^4$ gammas. It increases 600~700 gammas with the increament of $1^{\circ}$ in latitude. Along the same latitude, it decreases 10~90 gammas. with the increment of $1^{\circ}$ in longitude. Decreasing rate is considerably larger in higher latitude as the case of vertical component. (4) The declination ranges from $-3.8^{\circ}$ to $-11.5^{\circ}$. It increases $0.6^{\circ}$ with the increment of $1^{\circ}$ in latitude. Along the same latutude, it increases $0.6^{\circ}$ with the increment of l O in longitude. Unlike the cases of vertical and total component, the rate of change is considerably larger in lower latitude than in higher latitude. (5) The inclination ranges from $57.8^{\circ}$ to $66.8^{\circ}$. It increases about $1^{\circ}$ with 'the increment of $1^{\circ}$ in latitude Along the same latitude, it dereases $0.4^{\circ}$ with the increment of $1^{\circ}$ in longitude. (6) The Boundaries of 5 anomaly zones classified on the basis of the trend and shape of anomaly curves correspond to the geologic boundaries. (7) The trend of anomaly curves in each anomaly zone is closely related to the geologic structure developed in the corresponding zone. That is, it relates to the fault in the 3rd zone, the intrusion. of granite in the 1st and 5th zones, and mountains in the 2nd and 4th zones.

• 한국초전도ㆍ저온공학회논문지
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• 제24권4호
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• pp.40-45
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• 2022

The electrical/thermal stabilities and magnetic field controllability of a no-insulation (NI) high-temperature superconducting magnet are characterized by contact resistance between turn-to-turn layers, and the contact resistance characteristics are determined by properties of conductor surface and winding tension. In order to accurately predict the electromagnetic characteristics of the NI coil in a design stage, it is necessary to control the contact resistance characteristics within the design target parameters. In this paper, the contact resistance and critical current characteristics of a rare-earth barium copper oxide (REBCO) conductor were measured to analyze the effects of surface treatment conditions (roughness and oxidation level) of the copper stabilizer layer in REBCO conductor. The test samples with different surface roughness and oxidation levels were fabricated and conductor surface analysis was performed using scanning electron microscope, alpha step surface profiler and energy dispersive X-ray spectroscopy. Moreover, the contact resistance and critical current characteristics of the samples were measured using the four-terminal method in a liquid nitrogen impregnated cooling environment. Compared with as-received REBCO conductor sample, the contact resistance values of the REBCO conductors, which were post-treated by the scratch and oxidation of the surface of the copper stabilizer layer, tended to increase, and the critical current values were decreased under certain roughness and oxidation conditions.