• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.997-1002
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• 2013

The article is aiming to investigate the thermal-fluidic characteristics of magnetic fluid in a cavity using GSMAC (generalized-simplified marker and cell method). The transport equations of the magnetic fluid are including the continuity equation, momentum equation and energy equation for natural convection and Maxwell equation and magnetization equation of magnetite nano-sized particles motion. In addition, the heat transfer characteristics such as temperatures and Nusselt numbers and flow characteristics such as streamlines and isotherms of the magnetic fluid were analyzed with the intensity and direction of the magnetic fields. As a result, the thermal-fluidic characteristics of the magnetic fluid in a cavity were could be controlled by the intensity and direction of the magnetic fields.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.230-230
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• 2013

플라즈마를 활용한 미세 패턴의 건식 식각은 반도체 소자 공정에 있어서 가장 중요한 기술 중 하나이다. 한편, 매년 발행되는 ITRS Roadmap 에 따르면 DRAM 의 1/2 pitch 는 감소하는 동시에 Contact A/R (Aspect Ratio) 는 증가하고 있다. 이러한 추세 속에서 기존의 공정을 그대로 활용할 경우 식각물의 프로파일 왜곡 혹은 휨 현상이 발생하고 식각 속도가 저하되며 이러한 특성들이 결과적으로는 생산성의 저하로 이어질 수 있다. 이러한 현상을 최소화하기 위해서는 무엇보다 독립된 plasma parameter 들이 식각물의 프로파일 혹은 식각 속도 등에 어떠한 영향을 주는 지에 대한 학문적 이해가 필요하다. 본 논문에서는 최소 CD (Critical Dimenstion) 100nm, 최대 A/R 30 인 HARC (High Aspect Ration Contact hole) 의 식각 특성이 plasma parameter 에 따라 어떻게 변하는지 확인해 보고자 한다. 산화물의 식각은 대표적인 high density plasma source 중의 하나인 ICP에서 진행하였으며 기존에 알려진 plasma parameter 에 더하여 자장의 인가가 산화물의 식각 특성에 어떠한 영향을 주는지 살펴보고자 전자석을 ICP 에 추가로 설치하여 실험을 진행하였다. 결과적으로, plasma parameter 에 따른 혹은 자장의 세기 변화에 따른 산화물의 식각 실험을 플라즈마 진단 실험과 병행하여 진행함으로써 다양한 인자에 따른 산화물의 식각 메커니즘을 정확하게 이해하고자 하였다. 실험 내용을 요약하면 다음과 같다. 먼저, 전자석의 전류 인가 조건에 따라 축 방향 혹은 반경 방향으로의 자장의 분포가 달라질 수 있음을 확인하였고 플라즈마 진단 결과 축 방향 혹은 반경 방향으로의 자장이 증가하였을 때 고밀도의 플라즈마가 형성될 수 있음은 물론 반경 방향으로의 플라즈마 밀도의 균일도가 향상됨을 확인할 수 있었다. 또한 ICP 조건에서 바이어스 주파수, 압력, 바이어스 파워, 소스 파워, 가스 유량 등의 plasma parameter 가 산화물의 식각 특성에 미치는 영향 및 메커니즘을 규명하였고 이 과정을 통해 최적화된 프로파일을 바탕으로 축 방향 혹은 반경 방향으로 증가하는 자장을 인가하였을 때 (M-ICP 혹은 자화 유도 결합 플라즈마) ICP 대비 산화물의 식각 속도가 증가함은 물론 PR-to-oxide 의 선택비가 개선될 수 있음을 확인할 수 있었다. 자장의 인가에 따른 산화물의 정확한 식각 메커니즘은 향후의 실험 진행을 통해 이해하고 이를 통해 궁극적으로는 산화물의 식각 공정이 나아가야 할 올바른 방향을 제시하고자 한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.2
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• pp.173-179
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• 1990

This paper described to be measured the damping Characteristics in the artificial magnetic field in order to estimate the stabilited of the card and characteristic of movement of the directional system of the magnetic compasses made in Korea. The results obtained are summarized as follows. 1) It is compared by the elements of performance of the magnetic compasses made in Korea with the standards for magnetic compass of the IMO NAV/ANNEX II. The results are suitabled in the korean off shore, but it is unsuitabled in the high latitude sea than over the latitude 60 degree. 2) The characteristic of damping curve by the diameter of cards when the diameter of cards are 170mm and 175mm(clearance are 10.0m, 12.5mm), the fricative error is indicated the least than the other ones.

• Journal of Sensor Science and Technology
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• v.5 no.2
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• pp.29-36
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• 1996

With the three dimensional magnetic field measuring system dealt with in this paper, accurate measurements and analyses of extremely low frequency(ELF) magnetic fields caused by starting and/or operating electric devices and power installations can be conducted. To obtain high performance for lower frequency and spatial components without any distortion, the measuring system is designed as three dimensionally including the multiturn loop-type magnetic field sensors, differential amplifiers and active integrators. As the results of calibration experiments, the frequency response characteristics of the measuring system range from 8[Hz] to about 53[kHz] for each direction of x, y, z axes, and the response sensitivities are 9.54, 9.21, $10.89[mV/{\mu}T]$, respectively. The actual survey experiments by using an oscillating impulse current generator confirm a reliability of the proposed measuring system. Also, through the other experiments by using small-sized induction motors, the magnetic field intensities when starting and steady-state operating mark 15.8, $8.61[{\mu}T]$ as maximum value, respectively. And those intensities decrease steeply according as the measuring distance increases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.23-30
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• 2017

Most superconducting magnets which generate more than 20 T consist of nested magnets. A combination of LTS and HTS magnets is conventionally used, but high field magnets which use only HTS magnets have been developed recently. As HTS wires have very strong magnetic anisotropy, appropriate techniques should be used to consider this effect properly. The load line method has been conventionally used to design nested magnets for high field generation. Because this method considers only parallel and perpendicular magnetic fields, the effect of their orientation is not taken into account. In this paper, the actual orientation of the magnetic fields from 0 to 90 degrees is considered. The critical currents of the two kinds of high field nested magnets designed using the proposed method are calculated. The finite element method is used to calculate the distribution of the magnetic fields and the evolution strategy is used to find the critical current which maximizes the central magnetic field.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.28-34
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• 1985

This paper describes that the characteristic of movement and the performance of the directional system of the liquid magnetic compass analyze and investigate in the kinds of compass and the coefficient of viscosity of the liquid of compass, which the horizontal magnetic field of the geo-magnetic is varied from the equator to the polar region (0.39 gauss-0.03 gauss) by use of apparatus generating artificial magnetic fields. The results are as follows; 1. It is confirmed that the measured values and the calculated values on the characteristic of damping curve by the type of compass and coefficient of viscosity has almost agree with one another. 2. As the horizontal magnetic force geo-magnetic field approaches around the equator (0.39 gauss), the horizontal magnetic field get near the polar region (0.03 gauss), its period is to be longer and the compass card prove not to be more stabilized. 3. The coefficient of viscosity of the liquid in the A, B, C, D and E compasses used in the experiment is estimated 0.03 poises, 0.02 poises, 0.02 poises, 0.015 poises and 0.048 poises respectively by computer simulation.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.403-409
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• 1998

In this study, the effects of multi-dipole type of magnets on the characteristics of the inductively coupled plasmas and $SiO_2$ etch properties were investigated. As the magnets, 4 pairs of permanent magnets were used and, to etch $SiO_2, C_2F_6, CHF_3, C_4F_8, H_2$, and their combinations were used. The characteristics of the magnetized inductively coupled plasmas were investigated using a Langmuir probe and an optical emission spectrometer, and $SiO_2$ etch rates and the etch selectivity over photoresist were measured using a stylus profilometer. The use of multi-dipole magnets increased the uniformity of the ion density over the substrate location even though no significant increase of ion density was observed with the magnets. The use of the magnets also increased the electron temperature and radical densities while reducing the plasma potential. When $SiO_2$ was etched using the fluorocarbon gases, the significant increase of $SiO_2$ etch rates and also the increase of etch uniformity over the substrate were obtained using the magnets. In case of gas combinations with hydrogen, $C_4F_8/H_2$ showed the highest etch rates and etch selectivities over photoresist among the gas combinations with hydrogen used in the experiment. By optimizing process parameters at 1000 Watts of inductive power with the magnets, the highest $SiO_2$ etch rate of 8000 $\AA$/min could be obtained for 50% $C_4F_8/50% H_2$.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.06a
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• pp.164-165
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• 1996

임피던스 pprobe와 고전압 pprobe를 이용하여 평판형 유도결합 플라즈마에서의 용 량 결합 성분을 구하였으며, 용량 결합 성분에 의해서 생기는 석영창의 손상을 4극 질량 분 석기(quadruppole mass sppectrometer)를 이용하여 확인하였다. 또한 축방향 외부 자장을 가 하였을 경우 용량 결합 성분이 상당량 감소하여 석영창의 손상이 거의 없음을 확인하였다.

• 전기의세계
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• v.28 no.11
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• pp.3-13
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• 1979

현재 전개되고 있는 핵융합연구는 크게 두가지 방식으로 구분할수 있다. 즉 자장밀폐(Magnetic confinement)방식 및 관성밀폐(Inertial confinement)방식으로 구분된다. 관성밀폐방식에 의한 핵융합연구는 자장밀폐핵융합연구보다 훨씬 늦게 시작되었지만 그에 비슷한 큰 성과를 나타내고 있다. 특히 대출려글라스레이저에 의한 관성밀폐핵융합연구의 성과가 연저하다. 본문에서는 이 글라스레이저에 의한 핵융합에 관하여 그 개요를 해설하기로 한다.

• Journal of Radiation Protection and Research
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• v.37 no.1
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• pp.35-40
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• 2012

Several neutron measuring devices were tested under the neutron fields characterized with two distinct kinds of thermal and fast neutron spectrum. These neutron fields were constructed by the mixing of both thermal neutron fields and fast neutron fields. The thermal neutron field was constructed using by a graphite pile with eight AmBe neutron sources. The fast neutron field of 14 MeV was made by a DT neutron generator. In order to change the fraction of fast neutron fluence rate in each neutron fields, a neutron generator was placed in the thermal neutron field at 50 cm and 150 cm from the reference position. The polyethylene neutron collimator was used to make moderated 14 MeV neutron field. These neutron spectra were measured by using a Bonner sphere system with an LiI scintillator, and dosimetric quantities delivered to neutron surveymeters were determined from these measurement results.