• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.71-79
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• 2004

The deformed layers generated in face milling works were comparatively investigated to type 316L and nitrogen(N)-added type 316LN stainless steels. In order to characterize mechanical properties between type 316L and type 316LN, high-temperature tensile tests were conducted with different temperatures: R.T to $700^{\circ}C$. The cutting forces of three components, Fx, Fy and Fz were measured using a tool dynamometer through the face milling cutting tests. The deformed layers were measured by micro-hardness tests along deformed layers. The results of mechanical properties showed that type 316LN was superior to type 316L. The deformed layers of two steels were generated in the 1501m-3001m ranges, and type 316L was higher than type 316LN. The reason for this is due to the high strength properties by nitrogen effect. It was found that deformed structures were well observed for type 316L, but were minutely observed for type 316LN in this cutting conditions.

• Science of Emotion and Sensibility
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• v.2 no.2
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• pp.1-10
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• 1999

본 연구의 목적은 중추신경계 반응과 자율신경계 반응을 이용하여 향이 인간에 미치는 영향을 평가하고자 하는 것이다. 본 연구는 20-26세의 남자 10명, 여자 10명으로 구성된 피험자를 대상으로 이루어졌고, 100% Rose oil bulgrian, Lemon oil misitano, Jasmine abs., Lavender oil france (KIMEX.co.ltd) 등 4가지의 향을 사용하여 실험을 수행하였다. 전두엽 (Fz)과 두정엽 (Cz)에서 EEG를 기록하여 대역별 relative power spectrum 값을 구하고 $\alpha$대역에 대한 $\beta$대역의 비($\beta$/$\alpha$)를 통하여 향에 대한 감성 평가를 시도하였다. 또한 자율신경계 반응은 심전도, 피부온도, 피부저항의 생리신호를 측정하였다. 주관적 평가는 향의 세부적인 이미지를 나타내는 후각 감성 형용사를 이용하여, 양극의 7점 척도 25문항, 단극의 5점 척도 40문항, 그리고 각 향의 전반적인 선호도를 묻는 양극의 7점 척도 2문항으로 구성하여 자극제시 전, 후에 각각 실시하였다. 전체적으로 피험자들은 Lemon을 가장 쾌하고 연하다는 평가를, Rose를 가장 불쾌하며 진하다고 평가하였다. $\beta$/$\alpha$의 비는 쾌하고 연할수록 감소하였고 불쾌하고 진할수록 증가하였다. 또한 심박 변화율과 피부온도는 쾌하고 연할수록 감소하였고, 불쾌할수록 반대 결과를 나타내었다. 결론적으로 쾌하고 연한 향과 불쾌하고 진한 향 사이에 $\beta$/$\alpha$의 비와 자율 신경계 반응의 차이를 관찰할 수 있었다.

• Proceedings of the KAIS Fall Conference
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• 2002.05a
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• pp.151-154
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• 2002

반도체 소자의 기판 재료로 사용되고 있는 실리콘 웨이퍼는 그 정밀도가 매우 중요하다. 본 연구에서는 균일한 Dopant 농도 분포를 얻을 수 있는 중성자 변환 Doping을 이용하여 실리콘에 인(P)을 Doping하는 연구를 수행하였다. 중성자 변환 Doping, 즉 NTD(Neutron Transmutation Doping)란 원자번호 30인 실리콘 동위원소에 중성자가 조사되면 원자번호 31인 실리콘으로 변환되고, 2.6시간의 반감기를 갖고 decay 되면서 인(P)으로 변하게 되어 실리콘 웨이퍼에 n-type 전도를 갖게 하는 것을 말한다. 본 연구에서는 하나로 원자로를 이용하여 고저항(1000-2000Ωcm) FZ 실리콘 웨이퍼 에 두 개의 조사공에서 중성자 조사하여 저항의 변화를 관찰하였고, 중성자 조사시 발생하는 점결함을 분석하여 점결함이 저항 변화에 미치는 영향을 알아보았다. 중성자 조사 전 이론적 계산에 의해 HTS조사공은 5Ωcm, 20.1Ωcm 이고 IP3조사공은 5Ωcm, 26.5Ωcm, 32.5Ωcm 이었고, 중성자 조사 후 SRP로 측정한 결과 실제 저항값은 HTS-1 2.10Ωcm, HTS-2 7.21Ωcm 이었고, IP-1은 1.79Ωcm, IP-2는 6.83Ωcm, 마지막으로 IP-3는 9.23Ωcm 이었다. DLTS 측정 결과 IP조사공에서 새로운 피의 결을 발견할 수 있었다.

• Korean Journal of Biological Psychiatry
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• v.7 no.2
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• pp.180-185
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• 2000

Objective : The present study was designed to compare Global Field Power Measurement and conventional method in P300 determination. Method : The subjects were composed of patients(N=20) with schizophrenia by DSM-IV and normal controls(N=20). The auditory event related potential P300 was measured by "oddball paradigm". P300 components were determined by Global Field Power Measurement and conventional method at 5 electrodes(Fz, Cz, Pz, $T_3$, $T_4$). Results : P300 amplitudes of patients were smaller than those of controls across all electrodes and in both methods, but there was no differential power in P300 determination between two methods. Asymmetry of auditory event-related potential P300 was not shown between patients with schizophrenia and normal controls. Conclusion : It is implicated that it depends on clinical situations and research purposes what method of P300 determination will be more appropriate for patients with schizophernia.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.123-130
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• 2010

Electroencephalogram(EEG) would be the most objective psychophysiological research technique on human errors though few research has been taken yet. This study aimed to get characteristics of human error while committing simple Odd-Ball tasks by utilizing the power spectrum technique of EEG data. Each experiment was composed of 3 tasks with different rules, and 8 young undergraduate students participated in this study as paid subjects. The result showed in the affirmative that subject and the interaction of subject and task factors were statistically significant on variation of $\alpha$ band power $P_{\alpha/(\alpha+\beta+\theta)}$ and $\beta$ band power $P_{\beta/(\alpha+\beta+\theta)}$, and that the former increasing in backward direction to Pz reflects compatibility whereas the latter increasing in forward direction to Fz reflects familiarity. Therefore it was coucluded that, since task 2 carried out in the present research requiring decoding process would be more difficult to human beings than the task merely requiring psychological recall process, task 1 and task 3 were classified into a homogenious group excluding task 2, and the ratio $\alpha$ band power to $\beta$ band power indicated enormous increase of $\alpha$ band power relative to $\beta$ band power in the cases of contra-lateral errors, especially in task 2.

• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.384-391
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• 2006

Variation of brain dynamics under Zen meditation has been one of our major research interests for years. One issue encountered is the inaccessibility to the actual meditation level or stage as a reference. In this paper, we propose an alternative strategy for investigating the human brain in response to external flash stimuli during Zen meditation course. To secure a consistent condition of the brain dynamics when applying stimulation, we designed a recording of flash visual evoked potentials (F-VEPs) based on a constant background EEG (electroencephalograph) frontal $\alpha-rhythm$ dominating activities that increase significantly during Zen meditation. Thus the flash-light stimulus was to be applied upon emergence of the frontal $\alpha-rhythm$. The alpha-dependent F-VEPs were then employed to inspect the effect of Zen meditation on brain dynamics. Based on the experimental protocol proposed, considerable differences between experimental and control groups were obtained. Our results showed that amplitudes of P1-N2 and N2-P2 on Cz and Fz increased significantly during meditation, contrary to the F-VEPs of control group at rest. We thus suggest that Zen meditation results in acute response on primary visual cortex and the associated parts.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1999.06a
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• pp.253-269
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• 1999

The development of telecommunication and information technology requires to develop new piezoelectric materials with small size, low impedance, wide pass band width and high thermal stability of frequency. Langasite (La3Ga5SiO14) single crystal has been researched substitute of quartz and LiNbO3 for the applications of SAW filter, BAW filter and resonator. Its single crystal growth has been carried out by Czochralski Method. So, in order to get single crystal with higher quality, in this study, lnagasite (La3Ga5SiO14) single crystal was grown by using Floating Zone (FZ) method and characterized. For the growth of langasite single crystals, the langasite powder was synthesized at 135$0^{\circ}C$ for 5hrs and the feed rod was sintered at 135$0^{\circ}C$ for 5hrs. The growing rate was 1.5mm/h and the rotation speed was 15 rpm for an upper rotation and 13 rpm for a lower rotation. In order to prevent the evaporation of gallium oxide, Ar and O2 gas mixture was flowed. The growth direction was analyzed by Laue back-scattered analysis. The composition of grown crystal was analyzed suing XRD and WDS. The electrical properties of grown crystal at various frequencies and temperature were discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.368-376
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• 1996

$LiNbO_{3}$ single crystals (undoped, 5 mol% MgO-doped and 5 mol% ZnO-doped) were grown by the floating zone method which has the characteristics of a compositional homogeneity and uniform distribution of the dopants. The optimum growth condition was established experimentally and the defect structures such as domain structure, dislocation structure, slip band, and microtwins were characterized using a microscopic method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.310-313
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• 2002

Structures obtained with a direct boning of two FZ silicon wafers joined in such a way that a smooth surface of one wafer was attached to the grooved surface of the other were studied. A square net of grooves was made with a conventional photo lithography process. After high temperature annealing the appearance of voids and the rearrangement of structural defects were observed with X-ray diffraction topography techniques. It was shown that the formation of void free grooved boundaries was feasible. In the cases when particulate contamination was prevented, the voids appeared in the grooved structures could be eliminated with annealing. Since it was found that the flattening was accompanied with plastic deformation, this deformation was suggested to be intensively involved in the process of void removal. A model was proposed explaining the interaction between the structural defects resulted in "a dissolution" of cavities. The described processes may occur in grooved as well as in smooth structures, but there are the former that allow to manage air traps and undesirable excess of dislocation density. Grooves can be paths for air leave. According to the established mechanisms, if not outdone, the dislocations form local defect arrangements at the grooves permitting the substantial reduction in defect density over the remainder of the interfacial area.

• Journal of the Ergonomics Society of Korea
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• v.9 no.2
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• pp.29-35
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• 1990

To investigate and analyze of the human brain-wave changes during 3-dimenslonal image load were expected to take not only an important basic information of 3-dimensional TV usage but also 3-dimensional image design. In this experiment, to analyze the difference of visual analyze handing system for which we present the 2- dimensional image having no parallex and 3-dimensional image by visual evoked potentials(VEP). 2-dimensional image and 3-dimensional image displayed on the screen through video. In the test, the time interval was one sec for presentation of stimulus considering united time of visual information of right eye and left eye during watching the 3-dimensional image also display time interval was 200 mesc for each stimulus image. Results are as follow, (1) N190 appears faster 16msec-20msec in the point of Fz, Cz, Pz, Oz when loaded 3D4 angle than 2D3 angle. (2) About of the P300, 3D4 angle(Otherwise, Oz point was reverse) and in the case of no equipment of liquid crystal shutter, there appeared PEAK near the P250. (3) There were 5% significant difference when the liquid crystal shutter was equiped and didn't, Therefore, this phenomenon show the possibility that Liquid crystal shutter influences on Visual Evoked Potentials.