• 한국재료학회:학술대회논문집
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• 한국재료학회 1994년도 추계 학술발표 강연 및 논문 개요집
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• pp.1-1
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• 1994

;The electronic state calculations for various types of ceramic materials have beell performed by the use of $DV-X\;{\alpha}$ cluster method. The molecular orbital levels and wave functions for model clusters have been computed to study the electronic properties ami chemical bonding of the ceramics. For ${\beta}-sialon(Si_{6-z}Al_zO_zN_{8-z})$ which is a high temperature structural material based on ${\beta}-Si_3N_4$, we have made model cluster calculations to estimate the strength of chemical bonding between atoms by the Mulliken population analysis. It is found that the covalent bonding between Si and N atoms is very strong in pure ${\beta}-Si_3N_4$, but the covalency around solute atom is considerably weakened when Si atom is substituted by AI. This tendency is enhanced by an additional substitution of oxygen atom for N. The result calculated can well explain the experimental data of changes in mechanical properties such as the reductions of Young's modulus and Vickers hardness with increment of z-value in ${\beta}-sialon$. Various model clusters for transition metal oxides which show many interesting physical and chemical properties have also been calculated. High-valent perovskite-type iron oxides EMFe0_3E(M=Ca and Sr) possess very interesting magnetic and chemical properties. In these oxides, iron exists as $Fe^{4+}$ state, but the experimental measurement of Mossba~er effect suggests that disproportionation $2Fe^{4+}=Fe^{3+}+Fe^{5+}$ takes place for $CaFe0_3$ at low temperatures. The model cluster calculations for these compounds indicated the existence of considerably strong covalent bonding of Fe-O. The calculations of hyperfine interaction at iron neucleus show very good agreement with the experimental Mossbauer measurements. The result calculated also implies that the disproportionation reaction is strongly possible by assuming the quenching of breathing phonon mode at low temperatures.tures.

• 한국콘텐츠학회논문지
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• 제12권8호
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• pp.429-437
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• 2012

본 연구는 신체표현을 활용한 색깔과 화음, 다이내믹을 연결하여 일어나는 변화에 목적을 두고 있다. 본 연구를 통하여 영상미디어 음악치료 프로그램 모형개발을 위한 기초 자료 수집을 위해 심리적으로 화음과 다이내믹이 색깔에 변화를 준다는 것을 탐색하였다. 영상매체에서 음악은 비언어적 의사소통으로 많은 분야에서 사용된다. 특히 음과 색깔 관계의 심리적 변화를 통하여 가상과 현실의 갭을 줄이는 데에 가장 효과적인 도구이며 사용자는 메시지와 의미에 대해 우리의 감성을 유도한다. GIM (Method of Guided Imagery and Music)은 인간의 내면세계를 탐색하고 음악에 유도된 다양한 심상 경험을 통해 상징적 의미와 통찰로 자신을 이해하고 문제를 해결해가도록 하는 음악치료방법으로 인간의 내적세계를 광범위하게 다룬다. 본 연구를 통하여 영상미디어라는 도구를 기존의 음악치료에서 사용되어져 왔던 수동적이고 소극적인 음악 감상 활용방법에서 탈피하고 직접 몸으로 체험하는 능동적이고 적극적인 음악치료 프로그램 모형을 적용시켜 나아가 오늘날 급격히 변화하는 청소년기의 사회적응문제에서 긍정적 효과를 줄 수 있는 음악치료 프로그램개발 모형을 위한 기초 자료로 삼고자 한다.

• 한국인터넷방송통신학회논문지
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• 제15권1호
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• pp.261-267
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• 2015

다층 격자구조에서 전파하는 평면파들의 회절특성을 나타내는 고유치 문제는 모드 확장 원리에 의하여 정확하게 설명할 수 있다. 그런 모드 확장 원리들에 의존하는 모드 해들은 간단한 회로이며 일반적인 형태인 등가 전송선로 망에 의하여 분석할 수 있다. 이 해석법은 어떤 조건에서든 필드들의 격자 회절과정에 대한 상당한 물리적 직관성을 제공하는 해석적인 특성을 준다. 특히, 등가 전송선로 망은 다른 해석법들에서 해석적으로 구할 수 없는 회절 격자구조의 산란특성, 방출효과 그리고 다른 광학적 특성들을 체계적으로 평가하기 위한 컴퓨터 알고리즘의 템플릿으로서 사용될 수 있다. 본 논문에서 제안한 정확한 해석법의 타당성을 입증하기 위하여 앞서 연구한 논문들의 결과를 수치해석적으로 비교 분석하였다. 그 결과 본 논문에서 얻은 내용과 잘 일치함을 확인할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.60-60
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• 2015

Nanosheets of graphene and related 2D materials have attracted much attention due to excellent physical, chemical and mechanical properties. Single-layer graphene (SLG) was first synthesized by Blakely et al in 1974 [1]. Following his achievements, we initiated the growth and characterization of graphene and h-BN on metal substrates using surface segregation and precipitation in 1980s [2,3]. There are three important steps for nanosheet growth; surface segregation of dopants, surface reaction for monolayer phase, and subsequent 3-D growth (surface precipitation). Surface phase transition was clearly demonstrated on C-doped Ni(111) by in situ XPS at elevated temperatures [4]. The growth mode was clarified by inelastic background analysis [5]. The surface segregation approach has been applied to C-doped Pt(111) and Pd(111), and controllable growth of SLG has been demonstrated successfully [6]. Recently we proposed a promising method for producing SLG fully covering an entire substrate using Ni films deposited on graphite substrates [7]. A universal method for layer counting has been proposed [8]. In this paper, we will focus on the effect of competitive surface-site occupation between carbon and other surface-active impurities on the graphene growth. It is known that S is a typical impurity of metals and the most surface-active element. The surface sites shall be occupied by S through surface segregation. In the case of Ni(110), it is confirmed by AES and STM that the available surface sites is nearly occupied by S with a centered $2{\times}2$ arrangement. When Ni(110) is doped with C, surface segregation of C may be interfered by surface active elements like S. In this case, nanoscopic characterization has discovered a preferred directional growth of SLG, exhibiting a square-like shape (Fig. 1). Also the detailed characterization methodologies for graphene and h-BN nanosheets, including AFM, STM, KPFM, AES, HIM and XPS shall be discussed.

• Journal of Advanced Research in Ocean Engineering
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• 제3권4호
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• pp.165-173
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• 2017

This study aims at validating simulations of the forced and freely vibrating cylinders at Reynolds number of approximately 500 in order to identify the capability of the CFD code, and to establish the analysis process of the vortex-induced vibration (VIV). The direct numerical and large eddy simulations were employed to resolve the various length scales of the vortices, and the morphing technique was used to consider a motion of the circular cylinder. For the forced vibration case, both in- and anti-phase VIV processes were observed regarding the frequency ratio. Namely, when the frequency ratio approaches to unity, the synchronization/lock-in process occurs, leading to substantial increases in drag and lift coefficients. This is strongly linked with the switch in timing of the vortex formation, and this physical tendency is consistent with that of Blackburn and Henderson (J. Fluid Mech., 1999, 385, 255-286) as well as force coefficients. For the free oscillation case, the mass and damping ratio of 50.8 and 0.0024 were considered based on the study of Blackburn et al. (J. Fluid Struct., 2000, 15, 481-488) to allow the direct comparison of simulation results. The simulation results for a peak amplitude of the cylinder and a shedding mode are reasonably comparable to that of Blackburn et al. (2000). Consequently, based on aforementioned results, it can be concluded that numerical methods were successfully validated and the calculation procedure was well established for VIV analysis with reasonable results.

• 한국사회복지학회:학술대회논문집
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• 한국사회복지학회 2002년도 국제학술대회 자료집
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• pp.3-19
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• 2002

The problems and needs of families in Hong Kong are becoming more complex. Traditional family structures and functions are rapidly eroding. Moreover, family problems are further exacerbated by a growing number of socio-economic issues including rising divorce rates and extra-marital affairs. continuous family reunion migration from Mainland China, emotional and financial cost of caring for the older people and the changing economy which has pushed more families into hardship. In effect, more and more families are becoming vulnerable to risk. Traditional family services in Hong Kong are varied in mode, operation and provision, often overlapping in service boundaries with other family-oriented programs. In many instances, family service centers are stretched far beyond their capacity. As a consequence, they become too reactive, remedial and casework dominated. The University of Hong Kong Consultant Team recommended that family service programs have to protect vulnerable families and strengthen family capacities to promote maximum independence. The direction of family services is summarized as: strengthening families; child-centered, family-focused and community-based. New integrative family service centers aim at attaining the principles of promoting accessibility to users with minimum physical, psychological and administrative barriers; early identification of needs and intervention before the further deterioration of problems; integration of services cutting across program boundaries, and partnership between service providers to achieve efficient and effective use of scarce resources. Under the new model, multi-skilled teams can respond more proactively to a wide range of social needs, rather than addressing needs in isolation. To demonstrate the effectiveness of the new model, the consultant team has been commissioned by the government to evaluate the performance of these two-year pilot projects. More importantly, a coherent and family-friendly social policy should be formulated to strengthen family capacity against family-related problems.

• 천문학논총
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• 제32권1호
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• pp.131-133
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• 2017

We present the latest results from the Mission Program NIRLT (PI: I.Yamamura), the near-infrared spectroscopy of brown dwarfs using the AKARI/IRC grism mode with the spectral resolution of ~ 120. The near-infrared spectra in the wavelength range between 2.5 and $5.0{\mu}m$ are especially important to study the brown dwarf atmospheres because of the presence of major molecular bands, including $CH_4$ at $3.3{\mu}m$, $CO_2$ at $4.2{\mu}m$, CO at $4.6{\mu}m$, and $H_2O$ around $2.7{\mu}m$. We observed 27 sources, and obtained 16 good spectra. Our model fitting reveals deviations between theoretical model and observed spectra in this wavelength range, which may be attributed to the physical condition of the upper atmosphere. The deviations indicate additional heating, which we hypothesize to be due to chromospheric activity. We test this effect by modifying the brown dwarf atmosphere model to artificially increase the temperature of the upper atmosphere, and compare the revised model with observed spectra of early- to mid-L type objects with $H{\alpha}$ emission. We find that the chemical structure of the atmosphere changes dramatically, and the heating model spectra of early-type brown dwarfs can be considerably improved to match the observed spectra. Our result suggests that chromospheric activity is essential to understand early-type brown dwarf atmospheres.

• 한국의류산업학회지
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• 제9권1호
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• pp.6-14
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• 2007

The purpose of this study was to delve into what type of expression mode of fashion design could suit the life style of digital nomads, as the appearance of nomadic life style was concurrent with people's modified way of thinking and sociocultural changes in today's digital society. It's basically meant to define the roles of fashion design, which was discussed as a way of improving the quality of life as a sort of 'culture,' and to suggest some of the right directions for fashion design in the future. The culture of today's digital era is marked by a pursuit of high mobility and high speed, and by nomadic disposition that is built on flexible thinking. The kind of design that lets people carry nomadic things with them and thereby improve their mobility can satisfy their needs for mobility, and body-friendly design that functions as a device of information in itself can meet their needs for mobility as well. The leading example of the latter is a wearable computer, and wearable scientific technology will be taken to another level, thanks to the advance in digital technology. In the future, that will be more accessible to people in general, and subminiature digital equipment will gain popularity in fashion industry as part of textiles and clothing or as an accessory. And specific kinds of design will be widespread, including variable design, multi-functional design and modular design. The first serves as a tool to protect the human body and to facilitate the adaptability of it to the given circumstances, and the second is characterized by a superb physical and psychological protectability. The third lets wearers bring design to completion at their own option, owing to an increase in the number of open-minded people and the development of interactive media. All these types of design could be called a wearer-friendly, human-oriented design that is specifically appropriate for the digital age. Wearers can actively be involved in design process as productive consumers, which is expected to help increase opener practices in fashion design sector.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.95-105
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• 2012

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.

• Carbon letters
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• 제6권4호
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• pp.234-242
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• 2005

Bending and tensile properties of 2D cross-ply C/C composites with processing heat treatment temperature (HTT) are evaluated. C/C composites used are made from two types of PAN based T700 and M40 carbon fibers with phenolic resin as carbon matrix precursor. Both the types of composites are heat treated at different temperatures (ranging from 750 to $2800^{\circ}C$) and characterized for bending and tensile properties. It is observed that, real density and open porosity increases with HTT, however, bulk density does show remarkable change. The real density and open porosity are higher in case T-700 carbon fiber composites at $2800^{\circ}C$, even though the density of M40 carbon fiber is higher. Bending strength is considerably greater than tensile strength through out the processing HTT due to the different mode of fracture. The bending and tensile strength decreases in both composites on $1000^{\circ}C$ which attributed to decrease in bulk density, thereafter with increase in HTT, bending and tensile strength increases. The maximum strength is in T700 fiber based composites at HTT $1500^{\circ}C$ and in M40 fiber based composites at HTT $2500^{\circ}C$. After attending the maximum value of strength in both types of composite at deflection HTT, after that strength decreases continuously. Decrease in strength is due to the degradation of fiber properties and in-situ fiber damages in the composite. The maximum carbon fiber strength realization in C/C composites is possible at a temperature that is same of fiber HTT. It has been found first time that the bending strength more or less 1.55 times higher in T700 fiber composites and in M40 fiber composites bending strength is 1.2 times higher than that of tensile strength of C/C composites.