• Bulletin of the Korean Institute for Industrial Safety
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• v.1 no.1
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• pp.21-27
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• 2001

산업 발전과 인구의 급격한 증가에 따라 건축물은 고층화 및 인텔리젼트화 되어가면서, 화재로 인한 인적·물적 손실은 계속적으로 증가하고 있다. 따라서 과거보다 구체적이고 근본적인 대책의 마련이 필요하게 되었다. 현재의 소방시설의 설계는 사양중심(Prescriptive Based)의 체계로 되어 있다. 우리나라의 경우는 사양중심 체계로 되어있으나 외국에서의 공학적 도구와 연구를 바탕으로 하는 성능위주의 방화설계에 대한 연구가 시작되어 기존에 개발된 화재거동과 연기이동 및 피난의 소프트웨어를 이용하여 소방대상물의 열 분포, 연기이동, 피난특성, 발생열량 및 내화도 등을 분석함으로써 적합한 방화설계가 진행중이다.(중략)

• Electrical & Electronic Materials
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• v.4 no.2
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• pp.175-184
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• 1991

급속 열처리 방법으로 두께가 약 80.angs.C인 산화막을 성장시킨 후 950.angs.C와 1150.angs.C의 온도에서 15초-120초 동안 질화 및 재산화 공정을 수행하여 초 박막 구조의 질화 및 재산화된 질화 산화막을 성장하였다. 성장한 질화산 화막과 재 산화된 진화 산화막의 전기적 특성은 C-V, I-V, 전하 포획 및 TDDB 측정등을 통하여 분석하였다. 측정된 소자의 특성으로부터 질화 조건이 950.angs.C, 60초이고 재산화 조건이 1150.angs.C, 60초인 재산화된 질화 산화막은 전기적 스트레스 인가후에 전하 포획에 의한 평탄전압변화(.DELTA. $V_{fb}$ )와 계면 상태밀도( $D_{itm}$)의 증가가 산화막보다 적은 우수한 특성을 나타내는 것을 알 수 있었다.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1057-1072
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• 2018

In this study, micro-sized $CeO_2$ particles were synthesized by spray pyrolysis, and EG(ethylene glycol) and CA(citric acid) as organic additives were added to obtain hollow and porous particle during spray pyrolysis, and characteristics of obtained ceria were investigated according to the amount of added organic additives. Spray pyrolysis, postheat and ball-milling were combined to give 6 paths. $CeO_2$ nano-sized particle was obtained by the path which has sequence of Spray Pyrolysis with 0.5 M of EG and CA${\rightarrow}$Post-heat${\rightarrow}$Ball-milling${\rightarrow}$Post-heat among 6 paths. The average particle size(24 nm with standard deviation of 3.8 nm) of $CeO_2$ nano-sized particle by TEM analysis is close to the primary particle size(20 nm) which was calculated by Debye-Scherrer equation. To investigate the morphological characteristics and structure of the synthesized nanoparticle powders, SEM(Scanning Electron Microscopy), XRD(X-Ray Diffractometer) and TEM(Transmission Electron Microscopy) were used.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.265-265
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• 2016

호우가 홍수에 미치는 영향의 분석은 수문현상을 이해하고 수공구조물을 설계하는데 반드시 필요한 절차이다. 호우가 홍수에 미치는 영향을 분석하기 위해서 독립된 소유역부터 비독립된 대유역까지 홍수량을 계산하고 그 상관성을 이해해야 하지만 상류쪽의 소유역의 경우 관측자료의 부재가 빈번하여 이러한 전반적인 분석이 쉽지 않다. 그리고 소유역과 대유역의 홍수특성을 연관지어 분석하기 위해서는 비교가능한 홍수특성을 추출해야 하며 이러한 일관된 잣대를 사용한 홍수분석은 중요하다. 본 연구에서는 소유역의 자료부재를 보완하기 위해 자료공간확장 방법을 제안하고 이를 통하여 안동댐 유역내 총 50개 지점의 홍수 시계열자료를 생성하였다. 자료공간확장 방법으로써, 안동댐유역의 1989년부터 2009년까지의 자료의 질이 좋은 20개의 사상을 추출하였고 안동댐유역 내에 위치한 안동댐, 도산, 소천의 수위관측지점의 관측유량자료에 대해 분포형 모형인 GRM 모형의 매개변수를 시행착오법으로 동시에 보정하여 한 개셋의 최적 매개변수를 추정하였다. 이때 모의결과를 평가하기 위하여 Nash-Sutcliffe (NS) 계수를 사용하였으며 20갯 사상의 세군데 관측수위지점에 대해서 모의결과가 전반적으로 0.5 NS 계수 이상으로써 만족할 만한 결과를 얻었다. 이 추정된 매개변수는 47개의 추가적인 관심지점의 유출모의에 사용되었으며 이렇게 모의된 유출시계열 자료는 관측시계열 자료로 가정하여 사용하였다. 이렇게 공간확장되어 생성된 시계열 자료는 이동평균방법을 사용하여 홍수강도-지속시간 곡선으로 변환되었고 50개 유역의 평균강우량 시계열 자료 또한 같은 밥법을 사용하여 강우강도-지속시간 곡선으로 변환되었다. 50개 유역의 비교가능한 일관된 홍수특성을 추출하기 위해 비유량법의 유출계수를 계산하였다. 유출계수를 계산하기 위해 유역별 도달시간을 계산하였으며 이 도달시간에 해당하는 강우강도를 추출하였다. 그리고 유역별 첨두 홍수강도를 유역별 도달시간에 해당하는 강우강도로 나눠줌으로써 유역별 유출계수를 계산하였고 이 유출계수를 유역면적에 대해 도시함으로써 그 경향을 조사하였다. 조사 결과 유역면적이 $100km^2$ 이상으로써 상류에서 하류방향으로 유역이 중첩되면서 증가하는 비독립적인 유역들의 경우 유역면적이 증가함에 따라 유출계수가 작아지거나 커지는 어떠한 경향을 보였다. 하지만 유역면적이 $100km^2$ 이하로써 독립적인 소유역의 경우 유역면적이 증가함에 따라 유출계수는 무작위로 분포되었다. 이것은 비독립적인 유역의 경우에는 호우가 홍수에 어떠한 일관된 영향을 미치나 각각 독립된 소유역의 경우에는 일관된 영향을 미치지 않음으로써 지역화방법에 의한 독립된 인근 미계측유역의 유출추정은 그 신뢰성이 높지 않다는 것을 의미한다.

• Journal of the Korean Ceramic Society
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• v.24 no.3
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• pp.243-250
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• 1987

The effects aging on some properties and thermal-shock behavior of zirconia partially stabilized with 9 mol% MgO (9MZ) were studied. 9MZ specimens were aged over $1200^{\circ}$-$1400^{\circ}C$ for 12hours subsequently, after sintering at $1650^{\circ}C$ for 4 hours. Fracture strength(both before and after thermal-shock test), linear thermal expansion, monoclinic fraction and phase transition by XRD, density, galvanic potential and microstructure were measured. Quantitative chemical analysis around the grain-boundary of the specimen aged at $1350^{\circ}C$ was also conducted by EDX. The aging of 9MZ specimen causes a thermal decomposition of cubic-$ZrO^{2}$ into the formation metastable tetragonal-$ZrO^{2}$ and MgO. The former increases the residual strength after thermal-shock test and the latter improves the thermal-shock resistance due to thermal conduction through the continuous magnesia phase and the formation of monoclinic phase content in matrix were increased with decreasing the aging temperature from $1400^{\circ}C$ to $1200^{\circ}C$. Galvanic potential of the aged specimen exhibited a proper emf characteristic.

• Journal of Venture Innovation
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• v.3 no.2
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• pp.129-145
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• 2020

The purpose of this study was to examine the effects of the job characteristics of the PR practitioner on flourishing and to identify the mediating effect of the meaning of work and job engagement. This study used a survey of 353 PR practitioners from PR firms and the hypothesis was verified by gathering the data of the job characteristics, the meaning of work, the job engagement and the flourishing by conducting hierarchical regression analysis and SPSS Process Macro bootstrapping analysis. The results showed that the job characteristics of the PR practitioner were found to influence the flourishing with the double-mediation effect, the meaning of the work and job engagement. The more PR practitioners regard their work affects their surroundings, the higher the degree of autonomy is, and the more they get feedbacks they engaged more, as they valued their job more thereby experience flourish more. Moreover, when PR practitioners valued their job more, they more engaged in their work and experience flourish. The meaning of work revealed to be the important factor to affect flourish regardless of the job characteristics and the job engagement so that gained the results that PR firms' effort to elevate the meaning of work of PR practitioners has is important. The study findings suggest that PR practitioners' flourishing is manageable in the organization by paying attention to oneself in the aspect of the organization, not leaving in individual areas. Limitaions and implications for future studies were discussed.

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.171-176
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• 2000

The physical and electrical characteristics of MgO and Pt thin-films on it, deposited by reactive sputtering and rf magnetron sputtering, respectively, were analyzed with annealing temperature and time by four-point probe, SEM and XRD. Under annealing conditions of $1000^{\circ}C$ and 2 hr, MgO thin-film had the properties of improving Pt adhesion to $SiO_2$ and insulation without chemical reaction to Pt thin-film, and the sheet resistivity and the resistivity of Pt thin-film deposited on it were $0.1288\;{\Omega}/{\square}$ and $12.88\;{\mu}{\Omega}{\cdot}cm$, respectively. We made Pt resistance pattern on $SiO_2$/Si substrate by lift-off method and fabricated thin-film type Pt-RTD(resistance thermometer device) for micro thermal sensors by Pt-wire, Pt-paste and SOG(spin-on-glass). In the temperature range of $25{\sim}400^{\circ}C$, the TCR value of fabricated Pt-RTD with thickness of $1.0{\mu}m$ was $3927\;ppm/^{\circ}C$ close to the Pt bulk value. Resistance values were varied linearly within the range of measurement temperature.

• The Korean Journal of Applied Statistics
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• v.31 no.6
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• pp.707-719
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• 2018

Various time series representation methods have been proposed for efficient time series clustering and classification. Lin et al. (DMKD, 15, 107-144, 2007) proposed a symbolic aggregate approximation (SAX) method based on symbolic representations after approximating the original time series using piecewise local mean. The performance of SAX therefore depends heavily on how well the piecewise local averages approximate original time series features. SAX equally divides the entire series into an arbitrary number of segments; however, it is not sufficient to capture key features from complex, large-scale time series data. Therefore, this paper considers data-adaptive local constant approximation of the time series using the unbalanced Haar wavelet transformation. The proposed method is shown to outperforms SAX in many real-world data applications.

• Fire Science and Engineering
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• v.27 no.1
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• pp.31-38
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• 2013

The pressurized smoke control system is important for fire safety in building because it is directly concerned with egress time of people. Even though the damper plays an essential role in the pressurized smoke control system, the phenomena of backflow smoke occurs for a certain the damper position. The research for a position of damper effects on distribution of air flow at the fire door is not performed. In this study, numerical simulation using FDS 5.5 was carried out to analyze the effect of the position of damper on flow distribution at the fire door. To simulate real situation, effects of opening and closing of fire door was considered. As a result, when HRR was between 200 kW and 400 kW, in the case which the damper was on the opposite wall of the fire door, the back flow to the vestibules was large compared to the two other cases of damper position. But when HRR was above 400 kW, Effect on damper position was not occurred.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.65-73
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• 2006

The high temperature occurs due to the combustion gas from engine in unmanned aerial vehicles (UAV). The high temperature may cause serious damages in UAV structure. The Functionally Graded Material (FGM) is chosen as a candidate material of the engine duct structure. A functionally graded material (FGM) is a two- component mixture composed by compositional gradient materials from one material to the other. In contrast, traditional composite materials are homogeneous mixtures, and involve compositions between the desirable properties of the component materials. Since significant proportions of an FGM contain the pure form of each material, the need for compromise is eliminated. The properties of both components can be fully utilized. Thermal stress analysis of FGM layers (20, 40, 60, 80 and 100) is performed in this paper. In addition, the creep behavior of FGM applied in duct structure of an engine is analyzed for better understanding of FGM characteristics.