• 대한가정학회지
• /
• 제33권4호
• /
• pp.65-87
• /
• 1995

The purpose of this study was to investigate the consciousness, knowledge and food preferences for the Korean traditional foods, using a questionnaire survey for 560 high school students in seoul. The data were analyzed with simple frequency, percentage, t-test, chi-square test, dispersion analysis, Pearson's correlation and hierarchical multiple-regression analysis using the SPSS/PC+ Package system. The results of the survey are summarized as follows ; Girls showed a more interest in Korean traditional foods than boys. The motive of having interest in korean traditional foods were through mass communication or home education. Most of students were preffered korean traditional foods and were proud of native foods. The most preffered foods were Kim-chi and beverage. and they thought that color, appearance, foodstuff combination of Korean traditional foods were better than those of foreign foods. they showed a tendency to decrease the use Korean traditional foods because it is difficult to cook and they have little time to cook. They have taken more Korean traditional foods at home. Most students were responded that it is necessary to develope Korean traditional foods at home for the succeeding of korean dietary life culture. For the idea of improving Korean traditional foods, it is thought that simplified cooking method, new cooking method and fastfood is developed.

• 한국주조공학회지
• /
• 제13권3호
• /
• pp.238-247
• /
• 1993

Microstructure, hardness and wear characteristics of $SiC_p/Al-6.5wt%Si-1.7wt%Mg$ alloy composites fabricated by the method of rheo-compocasting and hot pressing are investigated in this study. The dispersion of SiC particles in the composites is homogeneous and the hardness improves as additional amount increases. The wear amount of the matrix metal increases highly as wear rates increase, for the wear mechanism changes from adhesive wear to melt wear, and the matrix metal was coated on the surface of revolving disc and its weight increases. In the 5vol% composites, Fe is adhered on the surface of specimen by the projection of the dispersed hard SiC particles which have net-work structure and the coating layer is about $300{\mu}m$. But in the composite more than 20vol%, the wear amount of composite decreases because the SiC particles which have superior hardness, wear resistance and heat resistance properties resist wear, the abrasive wear turn out predominant wear mechanism and so the wear amount of revolving disc increases.

• Computers and Concrete
• /
• 제7권5호
• /
• pp.469-482
• /
• 2010

This paper investigates the concrete permeability through a numerical and statistical approach. Concrete is considered as a random heterogeneous composite of three phases: aggregates, interfacial transition zones (ITZ) and matrix. The paper begins with some classical bound and estimate theories applied to concrete permeability and the influence of ITZ on these bound and estimate values is discussed. Numerical samples for permeability analysis are established through random aggregate structure (RAS) scheme, each numerical sample containing randomly distributed aggregates coated with ITZ and dispersed in a homogeneous matrix. The volumetric fraction of aggregates is fixed and the size distribution of aggregates observes Fuller's curve. Then finite element method is used to solve the steady permeation problem on 2D numerical samples and the overall permeability is deduced from flux-pressure relation. The impact of ITZ on overall permeability is analyzed in terms of ITZ width and contrast ratio between ITZ and matrix permeabilities. Hereafter, 3680 samples are generated for 23 sample sizes and 4 contrast ratios, and statistical analysis is performed on the permeability dispersion in terms of sample size and ITZ characteristics. By sample theory, the size of representative volume element (RVE) for permeability is then quantified considering sample realization number and expected error. Concluding remarks are provided for the impact of ITZ on concrete permeability and its statistical characteristics.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
• /
• pp.91-96
• /
• 2001

Restoration of contaminated soils to an environmentally acceptable condition is important. One of the newer techniques in soil remediation is a method based on electrokinetic phenomena in soils. The technology uses electricity to affect chemical concentrations and water flow through the pores of soils. An important advantage of electrokinetic soil remediation over other in-situ processes such as soil flushing is the capability of control over the movement of the contaminants. Because the migration of the contaminants is confined by the electric field, there is little dispersion outside the treatment zone. Furthermore, the process is effective for soils with low and variable permeability. In the present study, the distributions of cadmium in the electrokinetic processing of kaolinite under the condition of constant applied voltage are investigated. Cadmium accumulates near the cathode without reducing the diffusion of hydroxide ion into the soil. In keeping the catholyte pH at neutrality, cadmium migrates toward the cathode without any accumulation of cadmium near the cathode and is successfully removed at the cathode reservoir. It was also found that the progress of electrokinetic processing of cadmium could be gasped to a certain extent by monitoring the local voltage and the current density.

• Bulletin of the Korean Chemical Society
• /
• 제35권7호
• /
• pp.1979-1984
• /
• 2014

We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in $H_2$ and $O_2$ gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

• Archives of Pharmacal Research
• /
• 제29권12호
• /
• pp.1187-1192
• /
• 2006

The aims of this study were to encapsulate arbutin (AR) in liposome to enhance the skin-whitening activity, and to investigate the effect of liposome formulation on the entrapment efficiency (EE%), skin permeation rate and skin deposition. The liposomes were prepared by a film dispersion method with several different formulations and were separated from the solution by using the gel-filtration method. The physical (size distribution, morphology) and chemical (drug entrapment efficiency, hairless mouse skin permeation and deposition) properties of liposomes were characterized. The entrapment efficiency in all liposome formulations varied between 4.35% and 17.63%, and was dependent on the lipid content. The particle sizes of liposomes were in the range of $179.9{\sim}212.8\;nm$ in all liposome formulations. Although the permeation rate of AR in the liposome formulations decreased compared with AR solution, the deposition amount of AR in the epidermis/dermis layers increased in AR liposomal formulation. These results suggest that liposomal formulation could enhance the skin deposition of hydrophilic skin-whitening agents, thereby enhancing their activities.

• Journal of the Optical Society of Korea
• /
• 제17권3호
• /
• pp.262-268
• /
• 2013

We study the focusing properties of a two-dimensional square-lattice photonic crystal (PC) comprising silica and germanium partitioned cylinders in air background. The finite difference time domain (FDTD) method with periodic boundary condition is utilized to calculate the dispersion band diagram and the FDTD method incorporating the perfectly matched layer boundary condition is employed to simulate the image formation. In contrast to the common square PCs in which the negative refraction effect occurs in the first photonic band without negative phase propagation, in our suggested model system, the frequency with negative refraction exists in the second band and in near-infrared region. In this case, the wave propagates with a negative phase velocity and the evanescent waves can be supported. We also discuss the dependency of the image resolution and its location on surface termination, source location, and slab thickness. According to the simulation results, spatial resolution of the proposed PC lens is below the radiation wavelength.

• 한국전자파학회논문지
• /
• 제9권6호
• /
• pp.761-767
• /
• 1998

PML(Perfectly Matched Layer)은 넓은 주파수 대역에서 우수한 흡수 성능을 나타내므로 분산 특성이 강한 도파관 구조에 적합한 흡수경계조건이다. 본 논문에서는 기존의 PML의 계산 효율을 향상시키기 위해 새로운 알고리듬을 제안한다. 제안된 방법은 입/출력 포트의 한 변에서 필드를 모드로 전개한 후, 모드에 따라 홉수 경계조건을 적용한다. 제안된 방법은 1차원으로 계산 영역을 해석하므로 메모리와 계산 시간이 절약된다. 두 께가 두꺼운 비대칭 아이리스를 갖는 WG-90 구형도파관을 기존의 PML과 본 논문에서 제안한 1차원 모드 P PML을 적용하여 유한차분 시간영역법으로 해석을 한다. 제안된 방법의 계산 효율이 매우 뛰어남을 수치 계산을 통해 알 수 있다.

• Advances in aircraft and spacecraft science
• /
• 제6권6호
• /
• pp.479-495
• /
• 2019

Periodic cellular core structures included in sandwich panels possess good stiffness while saving weight and only lately their potential to act as passive vibration filters is increasingly being studied. Classical homogeneous honeycombs show poor vibracoustic performance and only by varying certain geometrical features, a shift and/or variation in bandgap frequency range occurs. This work aims to investigate the vibration filtering properties of the AUXHEX "hybrid" core, which is a cellular structure containing cells of different shapes. Numerical simulations are carried out using two different approaches. The first technique used is the harmonic analysis with commercially available software, and the second one, which has been proved to be computationally more efficient, consists in the Wave Finite Element Method (WFEM), which still makes use of finite elements (FEM) packages, but instead of working with large models, it exploits the periodicity of the structure by analysing only the unit cell, thanks to the Floquet-Bloch theorem. Both techniques allow to produce graphs such as frequency response plots (FRF's) and dispersion curves, which are powerful tools used to identify the spectral bandgap signature of the considered structure. The hybrid cellular core pattern AUXHEX is analysed and results are discussed, focusing the investigation on the possible spectral bandgap signature heritage that a hybrid core experiences from their "parents" homogeneous cell cores.

• 한국전산유체공학회지
• /
• 제22권1호
• /
• pp.95-102
• /
• 2017

Debris flow is a composition of solid objects of various sizes, suspension and water, which occurs frequently as the results of landslide following heavy rainfall. This often causes extensive damage in the form of socio-economic losses and casualties as witnessed during the incident around Mt. Umyeon, Seoul in 2011. There have been numerous investigation to mitigate the impacts from debris flow; however, the estimation as preparedness measure has not been successful due to nonlinear and multiphase characteristics of phenomena both in material and process inherent in the debris flow. This study presents a numerical approach to simulate the debris flow using open source code of computational fluid dynamics, OpenFOAM with non-Newtonian viscosity model for three phase material modeling. In order to validate the proposed numerical method, the quantitative evaluations were made by comparisons with experimental results and qualitative analysis for the dispersion characteristics was carried for the case of debris flow in the actual incident from Mt. Umyeon.