• 대한전자공학회논문지TE
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• 제37권2호
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• pp.1-5
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• 2000

금속이온 농도를 변화시켰을때의 IMI-O 고분자 LB막에 대한 단분자막의 거동과 MIM구조의 LB막 소자에 대한 전기 특성 및 유전 특성을 조사하였다. π-A 등온선의 측정에서 금속 이온 농도가 증가함에 따라 단분자가 차지하는 극한 단면적이 증가하였다. 이러한 변화는 금속이온 농도 변화에 따른 금속이온의 강도 증가에 의한 단분자막의 거동의 차이에 의한 것으로 생각된다. 전압-전류 특성에서 ohmic 영역의 기울기로부터 구한 전기전도도는 금속 이온의 농도가 증가할 수록 증가하였다. 이것은 전개분자와 금속이온간의 결합에 의한 극한 단면적의 변화가 전기전도도에 직접적인 관계가 있기 때문으로 생각된다. 한편, 유전 특성에서 금속이온의 농도가 증가할 수록 허수부 유전율이 최대가 되는 주파수 역시 증가하였다. 따라서 금속이온의 증가에 의해 완화시간 γ가 감소되는 것을 알 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.327-330
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• 1998

In this theory, we explained the impossibility of the motion or miving of the hole that has been recognized to be a carrier, by giving some fundamental reasons. We treated energy gap and impurity concentration, in p- and n-type region, as functions of the mobility that is one of te factors which determine current quantity, and analyzed the primary electron theory as a carrier by introducing 2 hypotheses.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.23-27
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• 1995

In sawing operation of synthetic jewelry, the performance of diamond cutter blade is very dependent on the blade variables. This investigation presents ecperimental results which show the effects of the blade variables such as types of diamond abrasives, grain size of diamond, concentration, and bond materials on the beavior of te blades. Based on the experimental results an optimum blade condition for the sawing of cubic zirconia was recommended.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.139.2-139.2
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• 2016

Electrons and phonons in chalcogenide-based materials play are important factors in the performance of an optical data storage media and thermoelectric devices. However, the fundamental kinetics of carriers in chalcogenide materials remains controversial, and active debate continues over the mechanism responsible for carrier relaxation. In this study, we investigated ultrafast carrier dynamics in an multilayered $\{Sb(3{\AA})/Te(9{\AA})\}n$ thin film during the transition from the amorphous to the crystalline phase using optical pump terahertz probe spectroscopy (OPTP), which permits the relationship between structural phase transition and optical property transitions to be examined. Using THz-TDS, we demonstrated that optical conductance and carrier concentration change as a function of annealing temperature with a contact-free optical technique. Moreover, we observed that the topological surface state (TSS) affects the degree of enhancement of carrier lifetime, which is closely related to the degree of spin-orbit coupling (SOC). The combination of an optical technique and a proposed carrier relaxation mechanism provides a powerful tool for monitoring TSS and SOC. Consequently, the response of the amorphous phase is dominated by an electron-phonon coupling effect, while that of the crystalline structure is controlled by a Dirac surface state and SOC effects. These results are important for understanding the fundamental physics of phase change materials and for optimizing and designing materials with better performance in optoelectronic devices.

• 전자공학회논문지D
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• 제34D권5호
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• pp.22-31
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• 1997

We have measured the optical properties, thickness, and energy band gap of the P $b_{1-x}$/100/L $a_{x}$100/ $Ti_{1-}$0.25x/100/ $O_{3}$ (PLT(x)) thin film prepared by the sol-gel method with varying the La concentration, x, fyom 15 nto 33 mol%. We have obtained the values from the tranmission spectrum and employed the envelope method in anayzing the spectrum. We have also performed the simulation of the transmission spectrum on the PC (personal computer) to verify the accuracy of the values 15 to 33mol%, the refractive index (at .lambda.=632.8nm) increases from 2.39 to 2.44. The extinction coefficient does not depend on the la concentration but mainly on te wavelength, and has the values between 0.2 and 0.5 at the wavelength shorter than 330nm and between 0.001 and 0.008 at the wavelength longer than 700nm. The energy band gap of the PLT (x) thin film has been obtained on the assumption of the direct band-to-band transition. It decreases from 3.28 to 3.17eV as the La concentration increases from 15 to 33 mol%. The thickness of the PLT(x) thin film has been also obtained in high accuracy by the envelope method..

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1436-1438
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• 1997

In this paper, CdS thin films, which were widely used window layer of the CdS/CdTe and the CdS/$CuInSe_2$ heterojunction solar cell, were grown by chemical bath deposition, and The properties were investigated in detail. Cadmium acetate and thiourea were used as cadmium and sulfur source, respectively. And Ammonium acetate was used as the buffer solution. Also Ammonia was used for controlling pH concentration. The reaction velocity was increased with increasing reaction temperature and decreasing pH concentration. The crystal structure of CdS films grown with various pH concentration had the hexagonal structure with (002) plane peak. In the range of pH $9{\sim}9.5$, the intensity of the peak was highest, and as increasing pH concentration, decreased the intensity of the peak except pH12.

• 동의신경정신과학회지
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• 제17권1호
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• pp.129-136
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• 2006

Objective : Audio-evoked potential is technique used for measuring brain functions such as memory, attention, and concentration. Although a number of studies on acupuncture for pain, there are few reports on the effect of acupuncture cognitive function. Methods : Fifteen healthy volunteers with no neurological condition took part of the study. $(23.27{\pm}2.09)$. In this study, we examined the changes in auditory P300 by acupuncture stimulation to 'Oegwan' on the left hand. Auditory P300 was recorded before, during and after acupuncture. The amplitude and latency of P300 at Fz, Cz, Pz point were calculated. Results : Auditory P300 amplitude decreased during and after acupuncture, but there was no statistical significance.(P< .05) Auditory P300 latency significantly decreased during and after acupuncture.(P< .05) Conclusions : The decrease of Auditory P300 latency time suggests that acupuncture at Oegwan has some effects on the cognitive function.

• 한국정밀공학회지
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• 제32권1호
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• pp.69-74
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• 2015

Cadmium telluride (CdTe) is being developed for thin film of the X-Ray detector recently. But a rough surface of the CdTe should be improved for resolution and signal speed. This paper shows the study on the improvement of surface roughness and removal rate by applying Chemical Mechanical Polishing. The conventional potassium hydroxide (KOH) based colloidal silica slurry could not realize a mirror surface without physical defects, resulting in low material removal rate and many scratches on surface. In order to enhance chemical reaction such as form oxidized layer on the surface of cadmium telluride, we used hydrogen peroxide ($H_2O_2$) as an oxidizer. Consequently, in case of 3 wt% concentration of hydrogen peroxide, the highest MRR (938 nm/min) and the lowest surface roughness ($R_{p-v}=10.69nm$, $R_a=0.8nm$) could be obtained. EDS was also used to confirm the generated oxide of cadmium telluride surface.

• 한국분말재료학회지
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• 제24권2호
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• pp.108-114
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• 2017

We fabricate fine (<$20{\mu}m$) powders of $Bi_{0.5}Sb_{1.5}Te_3$ alloys using a large-scale production method and subsequently consolidate them at temperatures of 573, 623, and 673 K using a spark plasma sintering process. The microstructure, mechanical properties, and thermoelectric properties are investigated for each sintering temperature. The microstructural features of both the powders and bulks are characterized by scanning electron microscopy, and the crystal structures are analyzed by X-ray diffraction analysis. The grain size increases with increasing sintering temperature from 573 to 673 K. In addition, the mechanical properties increase significantly with decreasing sintering temperature owing to an increase in grain boundaries. The results indicate that the electrical conductivity and Seebeck coefficient ($217{\mu}V/K$) of the sample sintered at 673 K increase simultaneously owing to decreased carrier concentration and increased mobility. As a result, a high ZT value of 0.92 at 300 K is achieved. According to the results, a sintering temperature of 673 K is preferable for consolidation of fine (<$20{\mu}m$) powders.

• 한국의류학회지
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• 제29권2호
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• pp.279-285
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• 2005

In order to activate the characteristics of charcoals in fiber systems, this study was carried out to experiment with the particle size from two micrometers to ten micrometers of charcoal powders on silk fabrics. The results obtained were as follows; The silk fabrics were dyed with gray color by charcoals effectively. The K/S value, that is indicative of the dye affinity, became higher as the increase of dyeing temperature, dyeing time, and dyeing concentration. Te dyeing effects were the highest with 50%(o.w.f.) of charcoals at $100^{\circ}C$ for 120 minutes in this experiments, It was observed the surfaces of silk fibers were mainly adcorbed with charcoal powders of the particle size from two micrometers to four micrometers by scanning electron microscope. Dyed silk fabrics showed comparatively low fastness to the fade of launding, the stain of the treatment of perspirations, and the strain of water fastness test, but good fastness to the stran of laundering, te drycleaning, the fade of treatment of perspirations, and the fade of water fastness test. In connection with the functional properties of dyed fabrics, the deodorizations were drastically improved, and the far-infrared emissions improved highly, and also the antibacterials were comparatively good.