• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.112-118
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• 2001

Magnetic field is commonly used in low temperature processing plasmas to enhance the performance of the plasma reactors. E$\times$B magnetron or surface multipole configuration is the most popular. However, the properties of capacitively coupled rf plasma confined by axial static magnetic field have rarely been studied. With these background, the effect of magnetic field on the characteristics of capacitively coupled 13.56 MHz/40 KHz argon plasma was studied, Ion saturation current, electron temperature and plasma potential were measured by Langmuir probe and emissive probe. At low pressure region (~10 mTorr), ion current increases by a factor of 3-4 due to reduction of diffusion loss of charged particles to the wall. Electron temperature slightly increases with magnetic field for 13.56 MHz discharge. However, for 40 KHz discharge, electron temperature decreased from 1.8 eV to 0.8 eV with magnetic field. It was observed that the magnetic field induces large temporal variation of the plasma potential. Particle in cell simulation was performed to examine the behaviors of the space potential. Experimental and simulation results agreed qualitatively.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.2
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• pp.108-113
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• 2009

MFL(magnetic flux leakage) inspection is a general method of non-destructive evaluation(NDE) of underground gas pipelines. Pipelines are magnetized by permanent magnets when MFL PIG(pipeline inspection gauge) gets through them. If defects or corrosions exist in pipelines, effective thickness is changed and thus variation of leakage flux occurs. The leakage flux signals detected by hall-sensors are analyzed to characterize defect's geometries such as length, width, depth, and so on. This paper presents several methods for estimating defect's length using MFL signals and their performances are compared for real defects carved in KOGAS pipeline simulation facility. It is found that 80% and 90% of minimum values for axial and peak values for radial signals respectively show the best performance in the point of length estimation error.

• Radiation Oncology Journal
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• v.12 no.3
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• pp.295-300
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• 1994

It was the purpose of present study to develop a new thermoseed for heating deep-seated tumors and assessment of the effect of magnetic control on thermoseeds. Aqueous suspension of iron micro spheres (Ferropolysaccharide) was injected directly into the VX-2 hepatoma and heated with 1.2 MHz inductive radiofrequency unit. Aqueous thermoseed suspension was delivered to the tumor by simple percutaneous injection. The limitation of the thermoseed heating method is the positional change of thermoseed particles in the tumor after implantation. The thermoseed particles could enter the systemic blood circulation and cause a severe embolization of a critical organ. To minimize this limitation, we have used the magnetic control after loading the thermoseed in the tumor, W hen ferropolysaccharides were exposed to a strong magnetic field, they magnetized and subsequently exerted a magnetic force on each other, forming larger aggregates of particles. The size of aggregated Particles were too big to enter the systemic blood circulation. Thus, unlike other thermoseed method, we hold the thermoseed particles stationary in the tumor. The temperature of the injected site and immediate vicinity elevated by $4-5^{\circ}C$. The temperature of the surrounding normal hepatic tissue elevated by $1-2^{circ}C$ only. The heating effect within the tumor was variable depending on the density of ferromagnetic aqueous suspension. Our results suggest that inductive heating of tumor injected with ferropolysaccharide solution offers the possibility of effective heat delivery to the defined tumor volume, which is difficult to heat with other heating devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.507-507
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• 2013

유리기판으로 투과되는 빛들 중에는 내부 전반사나 wave-guided mode로 인하여 손실이 일어나 일반적으로 20%의 광추출 효율을 가진다. 이러한 문제점을 해결하기 위한 연구에는 Photonic Crystal과 같은 주기적인 나노 구조물이 있는데 이러한 구조물을 제작하기 위한 마스크 공정 과정은 대부분 복잡하거나 비싼 단점이 있다. 이에 본 발표에서는 마스크 없이 비정질소다라임 유리의 구조물 생성으로 광 추출 효율이 상승하는지 보고자 하였다. M-ICP (Magnetized-Induced Coupled Plasma)란 용량 결합형 플라즈마와 유도 결합형 플라즈마 두 가지 방식의 플라즈마를 이용한 것인데 용량 결합형 플라즈마를 이용해 이온이 sheath에 의해 가속되어 유리표면에 부딪히고 그에 따라 유리가 식각되는 물리적 식각을 이용하였다. 또한 이온의 밀도를 조절하기 위해 유도결합형 플라즈마 방식을 이용하여 식각률을 높였다. 화학적 식각을 위해서는 CF4와 O2혼합 가스를 이용해 F가 Si와 결합하여 SiF4가 되어 사라지고 탄소잔여물인 C는 O2와 반응하여 제거하였다. 그 결과, 랜덤한 분포를 가지는 미세한 구조물(stochastic sub-wavelength structure)을 유리 표면에 형성할 수 있었고, 또한 다양한 가스 종류와 압력, source power와 bias power, 그리고 시간을 바꿔가며 미세 구조물들을 관찰하였다. 실험 결과, 가시광선 파장 이하의 높이를 갖고 수 마이크로미터의 너비를 갖는 구조물이 전반사되는 빛을 효율적으로 추출하는 것을 산란되는 빛의 정도인 diffusive transmittance 가 기존 0%에서 15% 정도로 증가하는 것으로 스펙트로포토미터 측정을 통해 확인하였다. 이러한 유리 기판 위 구조물 생성방법을 OLED에 적용한다면 적은 비용으로 소자의 효율을 크게 향상 시킬 수 있을 것이다. 또한 본 처리 과정의 장점은 기존의 방법에 필요한 스퍼터링이나 RTA 처리 과정이 필요 없어 공정 단가 절감과 제조 공정의 단순화로 높은 생산성을 얻을 수 있으며 대면적화에도 유리하다.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.193-209
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• 1996

Paleomagnetic and rock-magnetic data have been obtained from the Cretaceous rocks (Yeongdong Group, volcanic rock, and intrusive rocks) which are exposed in the Yeongdong Basin. The characteristic remanent directions of these rocks, which are mainly carried by magnetite and hematite of single and pseudo-single domain sizes, are normally magnetized (Yeongdong Group: $D/I=29.6/59.0^{\circ}C$, k=75.7, ${\alpha}_{95}=3.3^{\circ}$, N=25 sites, paleopole at $198.0^{\circ}E$, $66.4^{\circ}N$, K=46.1, $A_{95}=4.3^{\circ}$; volcanic rock: $D/I=352.8/44.1^{\circ}$, k=44.2, ${\alpha}_{95}=18.8^{\circ}$, N=3 sites, paleopole at $340.0^{\circ}E$, $78.8^{\circ}N$, $K=49.8^{\circ}E$, $A_{95}=17.6^{\circ}$X>; intrusive rocks: $D/I=358.4/51.9^{\circ}C$, k=20.0, ${\alpha}_{95}=13.8^{\circ}$, N=7 sites, paleopole at $338.1^{\circ}E$, $86.8^{\circ}N$, K=13.5, $A_{95}=17.1^{\circ}$). The stepwise unfolding of the characteristic remanent magnetization (ChRM) of the Yeongdong Group reveals that a maximum value of k is observed at 60% of unfolding with $D/I=13.0/58.6^{\circ}$ (k=124.62, ${\alpha}_{95}2.6^{\circ}$) indicating that the ChRM was aquired during ti1ting of the strata. This remagnetized ChRM in the sedimentary strata is due to acquisition of geomagnetic field direction at the time of formation of authigenic magnetic minerals, although it is not totally ruled out that the formation of authigenic magnetic minerals was affected indirect1y by the elevated temperature originated from the volcanic and intrusive rocks which intruded between Late Cretaceous and Early Tertiary.

• Korean Journal of Materials Research
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• v.8 no.3
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• pp.195-199
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• 1998

Magnetic and Magneto-Optical properties of Co-based MnSbPt thin films prepared by R.F Sputtering were investigated. In this study, the optimum heat treatment condition was found to be $300^{\circ}C$-4hours under a $5\times10^{-6}$ Torr, but perpendicularly magnetized thin films could not be obtained. Coercive force showed maximum value of about 5000e at $250\AA$ Co thickness but the value is not enough for practical use of the thin film. Heat treated Co-based MnSbPt thin film shows 0.78 degree of Kerr rotation angle for 700nm of incident wavelength.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.566-572
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• 2004

It is necessary to measure the direct current with a non-contact methodology for the liquid or gas phase, as welt as the conducting metals. This paper described a theoretical consideration and experimental verification for a non-contact quantitative direct current measurement system using the Faraday effect and magnetic flux leakage. The leakage of magnetic flux occurs around a gap when a ferromagnetic core including the discontinuous gap is magnetized. Two large anisotropic domains in a magneto-optical film are occurred by the vertical component of leaked magnetic flux and the domain walls are paralleled to the center of the gap. Here, the symmetrical arrangement of domains are deflected when a vertical magnetic field is applied to the magneto-optical film. The domain wall of the magneto-optical film are relocated when a measuring current passes through the ferromagnetic core. Therefore, a direct current passing through the core can be determined quantitatively by the measurement of moving distance of the domain wall.

• Korean Journal of Acupuncture
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• v.33 no.4
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• pp.213-220
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• 2016

Objectives : The aim of this paper is to develop acupuncture needle heating system by utilizing the new method which uses high frequency(HF) time-varying magnetic field. Also, it is possible to make an assessment for reliability and clinical significance of the system. Methods : We designed the system with solenoid coils for generation of HF time-varying magnetic field that oscillates at 150 kHz. Acupuncture needles are quickly magnetized and heated by 150 kHz. We assessed clinical significance of system, such as body temperature, pressure pulse waveform. Results : Temperature of acupuncture needle increased up to 60 degree. In the result for clinical significance of system, in case of manual acupuncture stimulation(MAS), body temperature change was $0.373^{\circ}C{\pm}0.224$(p<0.05), rate of pulse energy change increased about 7.6%. In case of warm acupuncture stimulation(WAS), body temperature change was $0.645^{\circ}C{\pm}0.281$(p<0.05), rate of pulse energy change remarkably increased about 35.9%. Conclusions : We confirm that the system is able to be applied clinically to various warm acupuncture needle therapy in the area of oriental medicine.

• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.152-159
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• 2014

Magnetic gear can transmit torque without any mechanical contact among rotational parts in rotating mechanical systems. Especially, magnetic gear using rare-earth PMs can be used in variety of industry application because of their great power efficiency. Thus, recent trend shows that magnetic gear can be replaced with common mechanical gear. This paper deals with comparison and torque analysis for magnetic gears with parallel and Halbach magnetization according to various design parameters. Using a two dimensional (2D) finite element (FE) analysis, suitable gear ratio is selected. We performed analysis for magnetically connected inner and outer torque with respect to various design parameters including thickness of inner and outer PM, steel pole angle, segments of Halbach array and magnetization pattern of inner and outer PMs. Finally, we can obtain improved design model having parallel and Halbach magnetization with larger torque, compared with an initial design model.

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.235-244
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• 2012

Nuclear magnetic resonance (NMR) logging has been considered one of the most complicated nevertheless, one of the most powerful logging methods for the characterization on of both rocks and natural fluids in formation. NMR measures magnetized signals (polarization and relaxation) between the properties of hydrogen nucleus called magnetic moment and applied magnetic fields. The measured data set contains two important petrophysical properties such as density of hydrogen in the fluids inside the pore space and the distinct decay rate for fluid type. Therefore, after the proper data processing, key petrophysical information, not only the quantities and properties of fluids but also supplies of rock characterization in a porous medium, could be archived. Thus, based on this information, several ongoing researches are being developed in estimating aspects of reservoir productivity information, permeability and wettability since it is the key to having correct interpretation. This study goes through the basic theory of NMR at first, and then reviews NMR logging tools as well as their technical characteristics. This paper also briefly discusses the basic knowledge of NMR simulation algorithm by using Random walk.