• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.14-19
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• 2021

The reduction of carbon dioxide emissions becomes a global issue, the main source of carbon dioxide emissions in the Asian region is the energy conversion sector, especially coal-fired power plants. We are working to develop technologies that will at least limit the increase in carbon dioxide emissions from the thermal power plants as one way to reduce carbon dioxide emissions. Our research aims to reduce carbon dioxide emissions by removing iron oxide scale from the feedwater system of thermal power plants using a superconducting high-gradient magnetic separation (HGMS) system, thereby reducing the loss of power generation efficiency. In this paper, the background of thermal power plants in Asia is outlined, followed by a case study of the introduction of a chemical cleaning line at an actual thermal power plant in Japan, and the possibility of introducing it into the thermal power plants in China based on the results.

• 한국연안방재학회지
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• 제5권4호
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• pp.173-182
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• 2018

As the research about increasing the efficiency of dredging soil transport, the technology, which reduce the friction between pipe wall and fluid in the pipe and disturbed generating pipe blockage, has been developed. So for the purpose of applying this technology to real construction site, main test has been tried at the real scale test in field. As a test result, this paper will show 30% flow efficiency increasing by permitted electro magnetic force to the pipe. And test result was evaluated as a ultra sonic velocity profiler. To propose the design technique and the execution manual of the high efficiency dredging material transport technic, this research have confirmed flow status changing depending on a soil material kind under electro-magnetic field and analyze the effect of electro-magnetic field which affects to each dredged soil material transportation. For achieving this research, EMF(Electro-Magnetic Field) generator is installed on the dredger(20,000HP) and through monitored flow status, dredging soil flow rate and sampled material specification is confirmed. Also dredger operating condition is measured and dredger power for soil transportation, hydraulic gradient and flow rate are compared, as transportation efficiency is calculated by this parameter, it is possible to check transportation efficiency improvement depending on each dredged soil material under electro-magnetic field. To verify the technique of dredged soil transfer using electromagnetic field, which is the core technique of the high efficiency dredged soil transfer, and the technique of expert system for pipeline transfer and the flow state. This could lead to a verification of transfer efficiency according to the characteristics of the dredged soil (sand, clay, silt) and the transfer distance (5km, 10km, 15km), which is planned to be used for a technology development of pump power reduction and long-distance transfer applying the high efficiency dredged soil transfer technology.

• 한국지구과학회지
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• 제38권4호
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• pp.251-262
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• 2017

드론을 이용한 신뢰성 있는 항공자력탐사 수행을 위해서 자력탐사 시스템과 드론 시스템을 구성하여 철광산 지역 자력 탐사에 적용하였다. 드론에 실리는 자력탐사 시스템은 Bartington사의 플럭스게이트 자력계 Mag639를 센서로 사용하고, A/D convertor를 이용하여 태블릿PC에 자력값이 저장되도록 구성하였다. 드론의 비행 컨트롤 모듈로는 확장성이 좋은 Pixhawk를 사용하였고, 적재 중량(Payload) 3 kg, 최대 중량 적재 시 15분 동안 비행이 가능하도록 구성하였다. 드론의 자기장 간섭 범위 측정 실험을 통해 드론에 의한 자기장 간섭효과를 제거하였고, 정확한 위치 정보 확보를 위해 RTK GPS를 적용하였다. 정확한 위치정보를 토대로 동일한 측선에 대해서 고도를 변경하여 두 번 측정해서 자력 변화율 자료를 확보하였다. 또한 지형 정보를 사용하여 지형을 따라 비행하는 비행경로를 설정함으로써 지형 효과를 없앨 수 있었다. 드론 기반 항공자력탐사 시스템을 통해 획득된 자력자료는 Geometrics사의 핵자력계 G-858을 이용해 동일 지역에서 획득한 자료와 양상이 일치함을 확인하였고, 이를 통해 드론 기반 항공자력탐사 시스템을 이용한 탐사 자료에 대한 신뢰성을 확보할 수 있었다.

• 한국표면공학회지
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• 제31권4호
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• pp.217-222
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• 1998

The Facing Targets Sputtering(FTS) system has several advantages for preparing films over a wide range of working gas pressure on plasma-free substrates. Co-Cr thin films seem to be one of the most promising media for perpendicular magnetic recording system. In this study, the capabillities of the system fordepositing C0-Cr films have been investigated. Under various Ar gas pressure, films with morphologically dense microstructure and good c-axis orientation were deposited, even when the incident angle $\psi_x$ of sputtered part icles to the film plane was below abount $50^{\circ}C$. this may imply that the shadowing effect by obique incidence of particle can be compensated by rapid surface diffusion owing to the high kinetic energy of particles arriving at the growing film. It has been confirmed that the FTS system is very useful for perparing Co-Cr thin films recorging media.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.286-288
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• 2007

The proposed method offers an improved control method for high power density AC/DC adapter by using more energy efficient electrical equipments. Power factor corrector (PFC) topology is based on boost topology with boundary conduction mode (BCM). DC/DC topology is based on half-bridge topology with newly introduced off-time control method, which helps to reduce size of the semiconductor and the magnetic devices. Test results with 85W AC/DC adapter (18.5V/4.6A) design shows that the measured efficiency is 90% with power density of $36W/in^3$. It also show low no load power consumption of about 0.5W.

• Asian Pacific Journal of Cancer Prevention
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• 제15권11호
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• pp.4487-4491
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• 2014

Objective: To explore the clinical manifestations and imaging characteristics of gliomatosis cerebri to raise the awareness and improve its diagnostic accuracy for patients. Materials and Methods: Clinical data, imaging characteristics and pathological examination of 12 patients with GC from Jan., 2008 to Jan., 2012 were analyzed retrospectively. Results: Patients with GC were clinically manifested with headache, vomiting, repeated seizures, fatigue and unstable walking, most of whom had more than 2 lesions involving in parietal lobe, followed by temporal lobe, frontal lobe, periventricular white matter and corpus callosum. Magnetic resonance imaging (MRI) showed diffuse distribution, T1-weighted images (T1WI) with equal and low signals and T2-weighted images (T2WI) with bilateral symmetrical high diffuse signals. There was no reinforcement by enhancement scanning and signals were different in diffusion-weighted images (DWI). The higher the tumor staging, the stronger the signals. Pathological examination showed neuroastrocytoma in which tumor tissues were manifested by infiltrative growth in blood vessels and around neurons. Conclusions: In clinical diagnosis of GC, much attention should be paid to the diffuse distribution of imaging characteristics, incomplete matching between clinical and imaging characteristics and confirmation by combining with histopathological examination.

• 한국분말재료학회지
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• 제23권4호
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• pp.276-281
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• 2016

Carbonyl iron (CI) is successfully incorporated as an additive into a polystyrene (PS) matrix via a highenergy ball milling method, under an n-hexane medium with volume fractions between 1% and 5% for electromagnetic interference shielding applications by the combination of magnetic CI and an insulating PS matrix. The morphology and the dispersion of CI are investigated by field emission scanning electron microscopy, which indicates a uniform distribution of CI in the PS matrix after 2 h of milling. The thermal behavior results indicate no significant degradation of the PS when there is a slight increase in the onset temperature with the addition of CI powder, when compared to the as-received PS pellet. After milling, there are no interactions between the CI and the PS matrix, as confirmed by Fourier transformed infrared spectroscopy. In this study, the milled CI-PS powder is extruded to make filaments, and can have potential applications in the 3-D printing industry.

• 한국전기전자재료학회논문지
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• 제34권5호
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• pp.386-392
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• 2021

Multiferroics exhibiting the coexistence and a possible coupling of ferromagnetic and ferroelectric order are attracting widespread interest in terms of academic interests and possible applications. However, room-temperature single-phase multiferroics with soft ferromagnetic and displacive ferroelectric properties are still rare owing to the contradiction in the origin of ferromagnetism and ferroelectricity. In this study, we demonstrated that sizable ferromagnetic properties are induced in the ferroelectric bismuth ferrite-barium titanate system simply by introducing Co ions into the A-site. It is noted that all modified compositions exhibit well-saturated magnetic hysteresis loops at room temperature. Especially, 70Bi_0.95Co_0.05FeO₃-30Ba_0.95Co_0.05TiO₃ manifests noticeable ferroelectric and ferromagnetic properties; the spontaneous polarization and the saturation magnetization are 42 µC/cm² and 3.6 emu/g, respectively. We expect that our methodology will be widely used in the development of perovskite-structured multiferroic oxides.

• 대한화학회지
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• 제44권3호
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• pp.194-199
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• 2000

The chemical behavior for Mo(0) and W(0) complexes, [M(CO)$_2$(PPh$_3$)$_4$] (M=Mo and W),has been investigated by UV-vis spectroscopic, magnetic, and electrochemical methods. Three absorption bands are observed in the UV-spectra. The crystal-field-splitti ng energy, spin-pairing energy, and bond strengths were deduced from the spectra. The metal d electrons in both complexes seemed to be delocalized in low-spin state.Metal ligand correlation appeared to strongly depend on bond strengths and diamagnetic properties. In electrochemical processes, both complexes exhibit an irreversible reduction wave.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.988-990
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• 2003

Disk type Single Phase SRM(Switched Reluctance Motor) can be used axial and radial direction magnetic flux. Therefore, the energy density per unit of volume is high and the axis can be shorter than that of any other motor. In this paper, the flux-linkage was measured according as rotor positions of disk type single phase SRM, which is designed and fabricated in previous studies. From the measured data, we got the magnetization curves, inductance profile, co-energy and torque. Also, we compared the value of the measurement with the value of analysis through 3D FEM simulation.