• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.791-794
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• 1999

Exact estimation of cement content in a hardened concrete can provide useful data to evaluate the quality and strength of the concrete and might be used to inspect the quality of precast concrete secondary products. Observation obtained in this research included : (1) the volume of coarse aggregate in the hardened concrete measured by the area comparison method has a high accuracy ; (2) the cement content in the mortar and the X-ray intensity of Ca-K$\alpha$ have a correlation factor of 0.96 ; (3) the cement content in the ready mixed concrete was estimated with high accuracy such as correlation factor of 0.99 and standard deviation of 0.64.

• KIEAE Journal
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• 제5권1호
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• pp.35-42
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• 2005

The primary concerns of recreation plan are to provide visitors with quality of recreational experience and to protect of recreation resources. The quality of recreational experience is often defined in terms of social carrying capacity. The carrying capacity is revealed as perceived crowding. In this respects, measuring perceived crowding is useful tool of social carrying capacity determination. This study is to test the structural equation model that includes variables affecting perceived crowding. Through an on-site questionnaire survey, 467 visitors on Naejangsan national park were collected. The results of the study are follows. The encounter level on facility area is higher evaluated as crowding factor than other area in the park. It can be concluded that visitor perceived crowding when facility area situates high density use level rather than other areas expose high density use level. In the path analysis, the input variables(attitude, experience, encounter level) on the structural equation model affect significantly on perceived crowding. Especially, the attitude on the park management polocy is the most affecting factor on perceived crowding.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권1호
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• pp.22-27
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• 2017

Purpose: The purpose of this study is to estimate the life time of OLED TV panel through electric current ADT(Accelerated Degradation Test). Methods: We performed accelerated degradation test for OLED TV Panel at the room temperature to avoid high temperature impact on the luminance. Results: we got more accurately the life time of the OLED TV when we applied ADT without temperature factor than including both current and temperature. Conclusion: Until now, the ADT of the OLED TV has been conducted with temperature and current at the same time for reducing test time and costs. We estimate incorrect life time when the temperature is adopted as an accelerated factor. Due to the high temperature impact on the luminance of the OLED TV panel. So as to solve this problem, we discard temperature and use electric current only.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.61-65
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• 2008

In this paper, we studied a ZnO-based film bulk acoustic resonator (FBAR) device fabricated on a specially designed multi-layerd Bragg reflector part. Very thin chromium adhesion layers (0,03um thick) were additionally deposited to improve the quality of the Bragg reflector and some thermal treatments were performed to improve the resonant characteristics of the device. At the operating frequency of ${\sim}2.7GHz$, excellent resonant characteristics were observed in terms of return loss and quality factor, and effective electromechanical coupling coefficient. These findings are expected to be highly promising and effective for improving the performance of the FBAR devices at high frequency.

• 반도체디스플레이기술학회지
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• 제2권1호
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• pp.11-14
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• 2003

The high Q(quality factor) suspended spiral inductors were fabricated on the silicon substrate by 3D surface micromachined process. The integration of 2.4GHz VCO has been performed by fabricating suspended spiral inductor of the top of CMOS VCO circuit. The phase noise of VCO integrated MEMS inductor is 93.5 dBc/Hz at 100kHz of offset frequency.

• E2M - 전기 전자와 첨단 소재
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• 제10권1호
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• pp.1-7
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• 1997

SAW filter has been used in mobile communication device, bandpass filter and resonator for merits )f miniaturization and high reliability. Materials for substrate mainly used single crystal such as LiNbO$_{3}$, LiTaO$_{3}$, ZnO. In this study, it was attempted that LiNbO$_{3}$ was substituted for piezoelectric ceramics(PZT4, PZT5A and PZT8) which had simple fabrication process because fabrication of crystal is difficult and it's cost is high. SAW filters were fabricated by the photolithography on piezoelectric ceramics substrates in order to compare their characteristics with LiNbO$_{3}$'s. The experimental value of center frequency was compared with theoretical one. The average difference of center frequency was 3.7%. PZT8 showed the best bandwidth properties among them. It is considered that PZT8 has higher mechanical quality factor and propagation velocity than others.

• 한국전기전자재료학회논문지
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• 제11권5호
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• pp.413-417
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• 1998

In this paper, we investigate frequency dependance of inductance of FeCoB amorphous magnetic films. $(Fe_{1-x}Co_x)_{79}Si_2B_{19}$ was used as the basic composition of amorphous magnetic film having near zero magnetostriction. The amorphous magnetic films were fabricated with x=0.94 and x=0.95 by using sputtering method at high frequency. The films were anneald under non-magnetic field and near crystallization temperatures(30min at $280^{\circ}C$, 30min and 1hr at $400^{\circ}C$, respectively). As the results of the experiments with the fabricated films, the lowest coercive force was 0.084[Oe] at 400[W] of the input power and the crystallization temperature was $360^{\circ}C$ . In the case 30min at 40$0^{\circ}C$ the inductance value in the low frequency with x=0.95 was higher by 488% than that with x=0.94. The quality factor Q was below 0.7 for all samples. We obtained the highest quality value at 400[KHz] with 30min at $280^{\circ}C$ and x=0.94. The value was about 0.62. Also, the quality factor value was about 0.35 at 1[MHz] with 30min at $280^{\circ}C$ and x=0.95.

• 한국대기환경학회지
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• 제28권3호
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• pp.282-293
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• 2012

This study aimed to show the chemical characteristics of $PM_{10}$ and $PM_{2.5}$ during Asian dust (AD) events and high PM episodes observed in Seoul. Time-resolved chemical composition of $PM_{10}$ or $PM_{2.5}$ was monitored in 1 hour interval using ambient ion monitor, semi-continuous carbon monitor, and on-line XRF spectrometer at Seoul intensive monitoring site in 2009. Considering that AD events were classified into three different cases according to the source area and pathway, the concentrations of ammonium-sulfate and trace metal components were relatively high when the AD were occurred in Gobi and inner-mongolia and transported across the Bohai bay. In addition, the influence of alkaline dust, which carried from saline land located in the northeastern China, was observed when the AD was originated from Gobi, inner-mongolia, and Manchuria. Except AD events, the high PM episodes observed in Seoul were impacted by various anthropogenic sources such as biomass burning, motor vehicle, oil combustion and road dust.

• 한국토양비료학회지
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• 제32권4호
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• pp.398-404
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• 1999

토양과 수질에 영향을 주는 주인자를 찾아내기 위하여 한강 수계에서 집약적 농업이 이루어지고 있는 지역을 대상으로 토양과 수질에 대한 요인 분석을 하였다. 화학성 분석을 위한 토양 시료는 고랭지 농업이 이루어지고 있는 평창군 일대에서 그리고 수질 시료는 한강의 소유역인 구리, 춘천, 둔내 및 대관령에서 1996년과 1997년에 채취하여 분석하였다. 분석된 토양의 질 11요소에 대한 상호 상관분석에서 55개 상관쌍 중 29개 상관쌍의 유의성이 인정되었다. 시료채취 적정성을 위한 전체 Kaiser값은 0.6이었다. 토양의 질 요소 중 부하가 큰값을 보이는 제1요인은 pH, Ca 및 Mg이었다. 제2요인은 인산과 미량요소이었으며, 제2요인은 인산과 미량요소이었으며, 제3요인은 유기물과 EC, 그리고 제4요인은 칼리와 철이었다. 수질 요소 20개의 190개 상관쌍 중 86개 상관쌍의 유의성이 인정되었다. 전체 Kaiser값은 0.74이었다. 수질요소 중 제1요인은 EC로 전체 변이의 27.1%를 차지하였으며 Na, Ca, SO4, Mg, K, Cl, NO3 그리고 T-N이 높은 부하를 보였다. 제2요인은 중금속 중 Zn, Fe, Mn 그리고 Cd이었다. 제3요인에서 제7요인은 각각 PO4, TSS, 무기질소, pH 와 T-P 그리고 Cu이었다. EC 요인 스코어는 구리에서 가장 높았고, 춘천, 둔내 및 대관령의 순이었다. 이 연구 결과는 요인 분석이 농업 소유역에서 토양과 수질에 영향을 주는 주요인 분석 선정에 유용함을 의미하였다.

• 음성과학
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• 제8권4호
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• pp.35-43
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• 2001

New speech synthesis algorithms capable of flexible prosody (especially F0) modification are desired for a high quality TTS system. TD-PSOLA is the most popular synthesis algorithm. The algorithm shows very high quality when F0 modification is limited. However, the quality degradation due to pitch epoch detection error becomes severe as the F0 modification factor becomes large. On the other hand, the vocoder framework is very flexible in F0 manipulation. The synthesized speech quality from the vocoder is far from natural human speech and suffers from buzziness. To remedy the buzzy quality from the vocoder and make more natural synthetic speech, we propose a mixed phase vocoder.