• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.04b
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• pp.35-36
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• 2002

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.323-326
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• 2002

본 연구는 새로 개발된 에어쿠션의자의 인체 적합성 검증에 관한 실험으로 기존 에어쿠션의자와 스펀지 매트의자를 새로 개발된 의자와 비교 평가 하였다. 본 연구를 위해 설문지를 통한 사용자의 감성 및 사용성을 측정하였고 객관적 검증에 필요한 체압분포측정을 하였다. 실험의 결과 사용성 평가에서 대부분의 피험자들이 신형 의자가 보다 편안하고 안락하다고 응답하였으며, 각 의자를 비교하는 전체 14항목의 설문 중 11개 항목이 의자A에서 중요도 순위가 좋게 나타났다. 체압분포에서도 좌판의 경우 신형 에어쿠션의자의 체압의 평균값이 적게 나오면서 고르게 분포하였고, 좌골결절을 중심으로 좌, 우 대칭이 되게 나왔다. 또한 등판부위에서도 등판의 수직선을 중심으로 체압분포가 좌, 우 대칭이 되게 나왔다.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1442-1443
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• 2006

본 논문에서는 분말 연자성체에 플라즈마를 이용하였을 때 특성 개선에 관한 연구이다. 기존의 압분 방식은 낮은 강도를 갖는 단점 때문에 신뢰성에 문제가 있어서, 직접적인 모터분야에 연자성체(SMC)를 적용하는데 큰 문제점 이였다. 그러나 본 논문에서 제안하는 SPS(Spark Plasma sintering)공법을 적용한 모터 코어 제조 방법은 플라즈마를 이용하여 분말의 표면에서만 접촉이 일어나게 하는 소결 방식으로, 내부재질의 특성변화 없이 표면의 절연층끼리만 접촉되게 하여 자기적 특성의 손상없이 기계적인 강도를 높일 수 있었다. 실제적으로 기존의 압분체(Hoganass550+윤활제(KE))의 경우 파단강도가 700Mpa정도였으나 SPS를 적용시 1200Mpa까지 증가 되었다. 이러한 SPS 공법을 통해 연자성체(SMC)재질의 모터 Core 분야 적용하는 데 생기는 문제점을 해결하고자 하였다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.11a
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• pp.30-30
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• 2000

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.57-58
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• 2013

• Proceedings of the Korean Magnestics Society Conference
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• 2001.04a
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• pp.54-55
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• 2001

• Journal of the Korean Magnetics Society
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• v.14 no.5
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• pp.174-179
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• 2004

Attenuation of conduction noise through microstrip line attached with the high lossy iron flakes-rubber composites has been investigated in GHz frequencies. Microstrip line was designed with characteristic impedance of 50 $\Omega$ and a length corresponding to the center frequency of 3 GHz. Iron flakes were fabricated by mechanical forging of spherical iron powders using an attrition mill. The fabricated microstrip line shows a ideal propagation characteristics of S$\sub$11/ < -60 dB and S$\sub$21/ = 0 dB. Attaching a noise absorbing sheet on the microstrip line, S$\sub$11/ increases to about -10 dB and S$\sub$21/ decreases to -20～-60 dB depending on the length of absorbing sheet. The calculated power loss is as high as 80% in the frequency range 2～8 GHz. It is suggested that the most critical material parameter is magnetic loss for the enhancement of noise attenuation.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.186-192
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• 1999

Dang-Chin feldspar powder with the mean particle size of 9.1 $\mu\textrm{m}$ was added to the synthesized mullite powder with the particle size of +325∼-200 mesh and the powder compact was prepared by PLPP(pressureless powder packing method). Densification behaviors were observed in sintering temperature range of 1200∼1400$^{\circ}C$. The binder solution of 4% PVA was infilterated into packed powder to the suitable strength. The PLPP method makes it possible to form compacts without clay as plasticizer. Therfore there was no defect caused by phase transition after sintering. Additionally, we observed the dense microstructure by the melting of feldspar. When the mullite compacts with feldspar of 30% were sintered at 1300$^{\circ}C$-4 hrs, we obtained the dense microstructure with zero water absorption and porosity <1%. When these compacts were sintered longer than 4 hrs at 1300$^{\circ}C$ or higher than 1400$^{\circ}C$, the examggerated grain growth of mullite was observed.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.270-275
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• 2005

Dust cores (compressed powder cores) of $Fe-6.0wt\%Si$ alloy with a size of $35\~180\;{\mu}m$ in diameter have been prepared by phosphate coatings and annealings at $600\~900^{\circ}C$ for 1 h in nitrogen atmosphere. Further the magnetic and mechanical properties of the powder cores were investigated. As a general trends, the compressive strength and core loss decreased with the increase in annealing temperature. When annealed at $800^{\circ}C$, the compressive strength was 15 kgf, the permeability and quality factor were 74 and 26, respectively. Moreover the core loss at 50 kHz and 0.1 T induction was $750\;mW/cm^3$, and the percent permeability under the static field of 50 Oe was estimated to be about 78. In addition, the cut-off frequency in the cure representing the frequency dependence of effective permeability was measured to be around 200 kHz. These properties of the $Fe-6.0wt\%Si$ alloy dust cores could be considered to be due to the good insulation effect of iron-phosphate coats, the decrease in magnetocrystalline anisotropy and saturation magnetostriction and the increase in electric resistivity.

• Journal of the Korean Magnetics Society
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• v.20 no.1
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• pp.13-17
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• 2010

Fe-3, 4.2 and 6.8% Si compressed cores were fabricated, and then electrical resistivity, AC and DC magnetic properties, microhardness, and other properties were analyzed in order to know whether best soft magnetic properties could be also obtained in an Fe-Si compressed core with the well-known composition of Fe-6.5% Si. With increasing the silicon content, eddy current loss and hysteresis loss decreased and increased, respectively, so that a minimum total loss was not obtained in the well-known Fe-6.8 % Si cores, but obtained in the Fe-4.2 % Si cores. Also electrical resistivity of the cores and hardness of the particles increased monotonously with silicon content so that compaction ratio of the cores decreased. B2 and $DO_3$ ordered phase could be observed only in Fe-6.8% Si powder. A minimum loss and highest permeability of the Fe-4.2 % Si cores can be explained by the ratio of specific electrical resistivity of insulator to that of magnetic particles, micro-hardness, compaction ratio and demagnetization coefficient of the Fe-Si powder particles with silicon content.