• 한국결정학회지
• /
• 제16권2호
• /
• pp.141-148
• /
• 2005

It is well known that the general metals have a lot of grain boundaries. The grain boundaries play a negative role to increase the resistivity and to decrease the conductivity. The small resistivity and the large conductivity have been a goal of the material scientists, and no signal noise, perfect signal transfer, and the realization of the real sound are the dream of electronic engineers and audio manias. Generally, oxygen free copper (OFC) and Ohno continuous casting (OCC) copper cables have been used for the purpose of the precise signal transfer and low noise. However they still include a lot of grain boundaries. In our study, we have grown the single crystal by the Czochralski method and succeeded to produce single crystal wires from the crystal in the dimension of $0.5{\times}0.5{\times}2500mm$. The produced wire still possesses very good single crystal properties. We observed the structure of the wire, and measured the resistance and impedance. Glow Discharge Spectrometer (GDS) was used for analyzing the compositions of copper single crystals and commercial copper. Current-Voltage curve, resistance, total harmonic distortion and speaker frequency response were measured for comparing electrical and acoustic properties of two samples.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.813-824
• /
• 2010

Thermal conductivity of soils is one of the most important parameters to design horizontal ground heat exchangers. It is well known that the thermal conductivity of soil is strongly influenced by its density and water content because of soil's particulate structure. This paper reviewed and evaluated some of the commonly used prediction models for thermal conductivity of soils with the experimental data available in the literature. Semi-theoretical models for two-component materials were found inappropriate to estimate the thermal conductivity of dry state sands. It came out that the model developed by Cote and Konrad gave the best overall prediction for unsaturated sands available in the literature. Also, a parametric analysis is conducted to investigate the effect of thermal conductivity and water content, soil type on the horizontal ground heat exchanger design. The analysis shows that a required pipe length for the horizontal ground heat exchanger is reduced with the increase of soil thermal conductivity and water content. The calculation results also show that the dimension of the horizontal ground heat exchanger can be reduced to a certain extent by using backfilling material with a higher thermal conductivity of solid particles.

• The Journal of Korean Physical Therapy
• /
• 제26권2호
• /
• pp.82-89
• /
• 2014

Purpose: This study was conducted in order to develop an instrument for the Korean Osteoarthritis Impact Measurement scale (KAIMS) in hip and knee osteoarthritis patients. Methods: A sample of 426 subjects was recruited in Ulsan metropolitan city (six hospitals and clinics) and Andong city (five hospitals and clinics) from June 2010 to May 2011. Item internal consistency and item discriminant validity were analyzed on the item-level, and floor (%) and ceiling (%) effect were analyzed on the scale-level. Exploratory factor analysis was performed for construction of items in the KAIMS instrument; confirmative factor analysis was also performed to test the fit of the model. Results: In 426 respondents, age was 64.3 years. The reliability for r coefficient 0.90 (mobility) and 0.89 (pain and stiffness) (Cronbach's alpha 0.95, 0.95 respectively) was high in the test-retest, and there was no significant difference in paired t-test (p>0.05). Item internal consistency (${\alpha}=0.92$, ${\alpha}=0.87$ respectively) was also high. It was constructed of two factors (mobility, pain and stiffness dimension) and nine items in explanatory factor analysis; results of confirmatory factor analysis also indicated that the dimensional structure model was fitted well in the test of model fit (${\chi}^2=83.83$, df=26, p=0.000; RMR=0.05; GFI=0.96; AGFI=0.83). Conclusion: In conclusion, the results of this study showed that the KAIMS that was developed was a reliable and valid instrument for measurement of osteoarthritis (OA) patients. We recommend further research for additional development of the instrument on OA in Korea.

• 건축역사연구
• /
• 제13권3호
• /
• pp.97-117
• /
• 2004

The tradition of architecture in the East and the West are different in many ways. One of the basic cause of such difference, however, is the different ways of perception of space and time. This paper aims to identify the attitude of perception of space and time in the cultures of the East and the West, and its influence on architecture. Degrees of importance placed on either space or time, as well as the modes of perception of space and time are discussed in relation to architecture. Basically, the architecture of the West seems to be more spatially oriented than the East, and this have much to do with the fact that the tradition of Western architecture is visually oriented. On the other hand, East Asian architecture have been more conscious on bodily feeling and its movement in architecture. Spatial units of traditional Eastern architecture, are arranged in such a way in which man can experience the change of space that is supposed to be organized to form a sequential message. Thus, in the East, temporal dimension is more deliberately included in the course of architectural experience compared to the cases of the West. Although it is not easy to attempt any kind of value judgment on such aspects, it is necessary to understand how the different perception of space and time influenced architectural outcome, especially when one wants to understand the cultural cause that have made the architectures of the East and the West very different. Such understanding is particularly important in East Asia where their future of architecture depends much on how they harmonize the Eastern and Western background which are already built up as two cultural structure in their consciousness to be able to create more desirable architecture for themselves.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.454-454
• /
• 2011

Graphene shows unusual electronic properties, such as carrier mobility as high as 10,000 $cm^2$/Vs at room temperature and quantum electronic transport, due to its electronic structure. Carrier mobility of graphene is ten times higher than that of Silicon device. On the one hand, quantum mechanical studies have continued on graphene. One of them is quantum Hall effect which is observed in graphene when high magnetic field is applied under low temperature. This is why two dimension electron gases can be formed on Graphene surface. Moreover, quantum Hall effect can be observed in room temperature under high magnetic field and shows fractional quantization values. Quantum Hall effect is important because quantized Hall resistances always have fundamental value of h/$e^2$ ~ 25,812 Ohm and it can confirm the quantum mechanical behaviors. The value of the quantized Hall resistance is extremely stable and reproducible. Therefore, it can be used for SI unit. We study to measure quantum Hall effect in CVD graphene. Graphene devices are made by using conventional E-beam lithography and RIE. We measure quantum Hall effect under high magnetic field at low temperature by using He4 gas closed loop cryostat.

• 한국측량학회지
• /
• 제28권2호
• /
• pp.207-215
• /
• 2010

현재 자연동굴을 대상으로 한 측량은 간이평판측량과 기록지측량의 두 가지 방법을 사용하고 있다. 이러한 방법을 통해 작성된 도면은 2차원이며, 간이평판과 기록지를 이용하기 때문에 전체 단면 및 모든 생성물들의 정확한 제원 파악이 어렵다. 이에 본 연구에서는 세계자연유산으로 등재된 용암동굴 중 당처물동굴(천연기념물 제 384호)을 대상으로 지상라이다와 고해상도 카메라를 활용하여 3차원 공간정보를 구축하였다. 또한 구조 분석, 단면 분석, 형태 분석, 생성물 분석을 통해 변형 및 변화 탐지의 기초데이터로써 3차원 공간정보의 활용가능성을 제시하였다.

• Journal of Magnetics
• /
• 제19권2호
• /
• pp.126-129
• /
• 2014

We report the crystallographic and magnetic properties of $Ni_{0.3}Fe_{0.7}Ga_2S_4$ by means of X-ray diffractometer (XRD), a superconducting quantum interference device (SQUID) magnetometer, and a M$\ddot{o}$ssbauer spectroscopy. In particular, $Ni_{0.3}Fe_{0.7}Ga_2S_4$ was studied by M$\ddot{o}$ssbauer analysis for evidence of spin reorientation. The chalcogenide material $Ni_{0.3}Fe_{0.7}Ga_2S_4$ was fabricated by a direct reaction method. XRD analysis confirmed that $Ni_{0.3}Fe_{0.7}Ga_2S_4$ has a 2-dimension (2-D) triangular lattice structure, with space group P-3m1. The M$\ddot{o}$ssbauer spectra of $Ni_{0.3}Fe_{0.7}Ga_2S_4$ at spectra at various temperatures from 4.2 to 300 K showed that the spectrum at 4.2 K has a severely distorted 8-line shape, as spin liquid. Electric quadrupole splitting, $E_Q$ has anomalous two-points of temperature dependence of $E_Q$ curve as freezing temperature, $T_f=11K$, and N$\acute{e}$el temperature, $T_N=26K$. This suggests that there appears to be a slowly-fluctuating "spin gel" state between $T_f$ and $T_N$, caused by non-paramagnetic spin state below $T_N$. This comes from charge re-distribution due to spin-orientation above $T_f$, and $T_N$, due to the changing $E_Q$ at various temperatures. Isomer shift value ($0.7mm/s{\leq}{\delta}{\leq}0.9mm/s$) shows that the charge states are ferrous ($Fe^{2+}$), for all temperature range. The Debye temperature for the octahedral site was found to be ${\Theta}_D=260K$.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.550-551
• /
• 2013

Large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER plasmas. Negative hydrogen (deuterium) ion sources are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck- Institute for Plasma Physics, Garching) for ASDEX-U and W7-AS neutral beam injection (NBI) systems. In recent, the first NBI system (NBI-1) has been developed successfully for the KSTAR. The first and second long-pulse ion sources (LPIS-1 and LPIS-2) of NBI-1 system consist of a magnetic bucket plasma generator with multi-pole cusp fields, filament heating structure, and a set of tetrode accelerators with circular apertures. There is a development plan of large-area RF ion source at KAERI to extract the positive ions, which can be used for the second NBI (NBI-2) system of KSTAR, and to extract the negative ions for future fusion devices such as ITER and K-DEMO. The large-area RF ion source consists of a driver region, including a helical antenna (6-turn copper tube with an outer diameter of 6 mm) and a discharge chamber (ceramic and/or quartz tubes with an inner diameter of 200 mm, a height of 150 mm, and a thickness of 8 mm), and an expansion region (magnetic bucket of prototype LPIS in the KAERI). RF power can be transferred up to 10 kW with a fixed frequency of 2 MHz through a matching circuit (auto- and manual-matching apparatus). Argon gas is commonly injected to the initial ignition of RF plasma discharge, and then hydrogen gas instead of argon gas is finally injected for the RF plasma sustainment. The uniformities of plasma density and electron temperature at the lowest area of expansion region (a distance of 300 mm from the driver region) are measured by using two electrostatic probes in the directions of short- and long-dimension of expansion region.

• Structural Engineering and Mechanics
• /
• 제78권5호
• /
• pp.599-610
• /
• 2021

Early detection of small concrete crack or reinforcement corrosion is necessary for Structural Health Monitoring (SHM). Global vibration based methods are advantageous over local methods because of simple equipment installation and cost efficiency. Among vibration based techniques, FRF based methods are preferred over modal based methods. In this study, a new coupled method using frequency response function (FRF) and proper orthogonal modes (POM) is proposed by using the dynamic characteristic of a damaged beam. For the numerical simulation, wave finite element (WFE), coupled with traditional finite element (FE) method is used for effectively incorporating the damage related information and faster computation. As reported in literature, hybrid combination of wave function based wave finite element method and shape function based finite element method can addresses the mid frequency modelling difficulty as it utilises the advantages of both the methods. It also reduces the dynamic matrix dimension. The algorithms are implemented on a three-dimensional reinforced concrete beam. Damage is modelled and studied for two scenarios, i.e., crack in concrete and rebar corrosion. Single and multiple damage locations with different damage length are also considered. The proposed methodology is found to be very sensitive to both single- and multiple- damage while being computationally efficient at the same time. It is observed that the detection of damage due to corrosion is more challenging than that of concrete crack. The similarity index obtained from the damage parameters shows that it can be a very effective indicator for appropriately indicating initiation of damage in concrete structure in the form of spread corrosion or invisible crack.

• 한국의류학회지
• /
• 제46권5호
• /
• pp.848-867
• /
• 2022

As an emerging market with rapid economic growth, while being a key region of the K-culture expansion, Vietnam draws increasing scientific attention. This study focuses on the MZ generation, Vietnam's leading consumer group, revealing their consumption value structure. An online survey was used for data collection purposes, investigating 368 Vietnamese consumers between 18-37 years of age. Six value dimensions were derived as results of the present analysis: functional, emotional, social, ethical, self-expression, and autonomy-oriented value. Among them, functional value includes two sub-dimensions of utility and price, while emotional value entails three sub-dimensions, namely hedonism, novelty, and aesthetics. 'Self-expression value' and 'autonomy-oriented value', reflecting the characteristics of the MZ generation, who actively express themselves and respect proactive decision-making, are becoming important standards of the consumption attitude of young Vietnamese. Moreover, the pursuit of 'novelty' was derived as a factor reflecting emotional values, revealing an association between hedonic consumption, and seeking for newness and difference. Furthermore, the relationships between each consumption value dimension, respective demographic characteristics, and global consumption propensity were investigated. The present findings aim to provide insights into young Vietnamese consumers' attitudes and intend to serve as a foundation for future research.