• 한국전기전자재료학회논문지
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• 제23권5호
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• pp.358-363
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• 2010

The polishing pad is important element for polishing characteristic such as material removal rate(MRR) and within wafer non-uniformity(WIWNU) in the chemical mechanical planarization(CMP). The result of the viscoelasticity measurement shows that 1st elastic modulus is increased and 2nd elastic modulus is decreased when the top pad is thickened. The finite element analysis(FEA) was conducted to predict characteristic of polishing behavior according to the pad thickness. The result of polishing experiment was similar with the FEA, and it shows that the 1st elastic modulus affects instantaneous deformation of pad related to MRR. And the 2nd elastic modulus has an effect on WIWNU due to the viscoelasticity deformation of pad.

• 한국세라믹학회지
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• 제48권4호
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• pp.269-277
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• 2011

Glass-ceramics based on lithium disilicate($Li_2Si_2O_5$) are prepared by heat-treatment of glasses in a system of $SiO_2-Li_2O-K_2O-Al_2O_3$ with different compositions. The crystallization heat-treatment was conducted at the temperature range of $700{\sim}900^{\circ}C$ and samples were analyzed by XRD and SEM. Mechanical properties were determined by a Vicker's hardness and 4 point bending strength. When $SiO_2/Li_2O$ ratio increased, cristobalite and tridymite crystals showed more predominate than lithium disilicate crystals. Increase in $Al_2O_3$ contents in the glass suppressed crystallzation of lithium disilicate crystals. Increase in ZnO, $B_2O_3$ contents in the glass decreased crystallization temperature of lithium disilicate crystals, and increased mechanical properties because of the reduction of the lithium disilicate crystal size.

• Food Science and Biotechnology
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• 제27권6호
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• pp.1871-1875
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• 2018

Preventive and curative activity of postharvest treatments with chitosan nanoparticles (CS) and chitosan biocomposites loaded with pepper tree essential oil (CS-PEO) against anthracnose were evaluated on Avocado (Persea americana) cv. Hass artificially inoculated in rind wounds. After 10 days of storage significant preventive and curative activity against Colletotrichum gloeosporioides was observed with the absence of internal damage by applying CS and CS-PEO. Quality parameters like water losses and firmness changes were assessed on fruit treated. CS and CS-PEO were effective to reduce water losses and firmness losses.

• 한국화재소방학회논문지
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• 제25권5호
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• pp.100-107
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• 2011

본 연구에서는 비상시 인명피해의 위험요소인 연기발생에 따른 시야장애 상황을 연출하여 음성피난유도 시스템의 적용을 위한 모의실험을 실시하였으며 피험자들의 피난행동과 피난 대피시간을 조사 분석하였다. 피난유도음을 스피커 4개에서 동시에 발생시킬 경우, 대부분의 피험자는 방향감을 상실하고 지정된 지점으로 이동하는 시간도 비교적 길게 나타났다. 스피커 2개보다 1개에서 피난유도 멘트가 나왔을 때 방향감 및 피난행동에 가장 좋은 결과를 보여주었다. 또한 2개 이상의 스피커에서 피난유도 멘트가 동시에 발생되었을 때는 선행음효과를 활용하고, 스피커 설치가 가까울수록 피난유도 내용 및 방향감 인지가 높고 대피시간도 짧은 것으로 나타났다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.152.1-152.1
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• 2008

• 한국전자통신학회논문지
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• 제6권5호
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• pp.703-708
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• 2011

본 논문에서는 대형 교회를 제외한 대부분의 교회가 협소한 공간에 많은 청중을 수용하고자 발코니 층을 설치하여 음의 사각지역 및 음상 정위가 어긋난 지역이 발생하는 문제를 경제적 관점에서 컴퓨터 시뮬레이션을 이용하여 음의 사각지역 및 음상의 개선하는 해결방안을 제시한다. 본 연구에서는 특정교회에 대하여 컴퓨터 시뮬레이션 툴로 경제적으로 쉽게 구할 수 있는 Mapp online으로 사용하였으며, 서브 스피커의 추가 설치 및 메인 스피커 대비 서브 스피커의 -10 dB 이득조절로 명료도를 실측값과 비교한 결과 약 52% 상승하여 명료도가 "보통"에서 "아주 좋음" 단계로 개선됨을 확인할 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1227-1230
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• 1998

Phase control methods are used to expand the sound image in general AV system. However, these methods are effective only to the signal under 1kHz, and the listener must be located in front center of the speaker system. In this paper, we realize the realtime processing system in which phase shifting method is dominant at low frequency and precedence effect is dominant at high frequency. Two sound cards are used to process the audio signal in realtime with 16 bits stereo channel of 44.1 kHz sampling frequency. And the analog circuit is designed to process the phase shifting. In experiments the usefulness of the proposed stereo system is confirmed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.394-394
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• 2013

The spin-orbit interaction has received great attention in the field of spintronics, because of its property and applicability. For instance, the spin-orbit interaction induces spin precession which is the key element of spin transistor proposed by Datta and Das, since frequency of precession can be controlled by electric field. The spin-orbit interaction is classified according to its origin, Dresselhaus and Rashba spin-orbit interaction. In particular, the Rashba spin-orbit interaction is induced by inversion asymmetry of quantum well structure and the slope of conduction band represents the strength of Rashba spin-orbit interaction. The strength of spin-orbit interaction is experimentally obtained from the Shubnikov de Hass (SdH) oscillation. The SdH oscillation is resistance change of channel for perpendicular magnetic field as a result of Zeeman spin splitting of Landau level, quantization of cyclotron motion by applied magnetic field. The frequency of oscillation is different for spin up and down due to the Rashba spin-orbit interaction. Consequently, the SdH oscillation shows the beat patterns. In many research studies, the spin-orbit interaction was treated as a tool for electrical manipulation of spin. On the other hands, it can be considered that the Rashba field, effective magnetic field induced by Rashba effect, may interact with external magnetic field. In order to investigate this issue, we utilized InAs quantum well layer, sandwiched by InGaAs/InAlAs as cladding layer. Then, the SdH oscillation was observed with tilted magnetic field in y-z plane. The y-component (longitudinal term) of applied magnetic field will interact with the Rashba field and the z-component (perpendicular term) will induce the Zeeman effect. As a result, the strength of spin-orbit interaction was increased (decreased), when applied magnetic field is parallel (anti-parallel) to the Rashba field. We found a possibility to control the spin precession with magnetic field.

• 대한전자공학회논문지SP
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• 제48권4호
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• pp.142-152
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• 2011

일반적으로 기존의 비상 대피용 유도 시스템은 비상등 또는 유도 LED와 같이 시각적인 부분에 의존하고 있다. 실제로 화재인 경우에는 연기 때문에 시야 확보가 힘든 경우가 많다. 본 논문에서는 이런 경우를 대비하여 방향성을 가진 음향을 사용하여 비상 대피 유도 시스템을 설계 및 구현하였다. 이 때 모든 스피커는 편리한 설치를 위해 오디오 직렬 전송 기법을 사용하였다. 대피 경로를 위한 최단 경로 알고리즘은 플로이드 알고리즘을 사용하였다. 오디오 직렬 전송 기법의 단점인 단선에 대한 대책으로 자동 고장 진단 기법을 제안하였다. 시스템 제어와 감시는 PC와 USB 프로토콜 연결을 통하여 이루어진다. 제안한 시스템은 가상의 비상 대피 환경에서 표본 집단의 대피 실험의 효율성을 검증했다. 결론적으로 제안된 시스템은 비상 상황에서 대피율의 증가를 확인하였고 오디오 직렬 전송 기법으로 쉽고 저가의 비용으로 설치 가능하다.

• The Journal of Advanced Prosthodontics
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• 제9권2호
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• pp.130-137
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• 2017

PURPOSE. The purpose of this study was to evaluate the effect of nano-structured alumina surface coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements. MATERIALS AND METHODS. A total of 90 disk-shaped zirconia specimens (HASS CO., Gangneung, Korea) were divided into three groups by surface treatment method: (1) airborne particle abrasion, (2) tribochemicalsilica coating, and (3) nano-structured alumina coating. Each group was categorized into three subgroups of ten specimens and bonded with three different types of dual-cured resin cements. After thermocycling, shear bond strength was measured and failure modes were observed through FE-SEM. Two-way ANOVA and the Tukey's HSD test were performed to determine the effects of surface treatment method and type of cement on bond strength (P<.05). To confirm the correlation of surface treatment and failure mode, the Chi-square test was used. RESULTS. Groups treated with the nano-structured alumina coating showed significantly higher shear bond strength compared to other groups treated with airborne particle abrasion or tribochemical silica coating. Clearfil SA Luting showed a significantly higher shear bond strength compared to RelyX ARC and RelyX Unicem. The cohesive failure mode was observed to be dominant in the groups treated with nano-structured alumina coating, while the adhesive failure mode was prevalent in the groups treated with either airborne particle abrasion or tribochemical silica coating. CONCLUSION. Nano-structured alumina coating is an effective zirconia surface treatment method for enhancing the bond strength between Y-TZP ceramic and various dual-cured resin cements.