• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.750-755
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• 2005

This paper proposes a small VCM (Voice coil motor) type actuator using curved suspensions for auto-focusing and zoom motions for mobile information devices. 1'he proposed focusing actuator adopts a nontraditional type of suspension using curved beams in order to extend output displacement within small height restriction. The curved beam is similar to the leaf spring type which is usually used in optical disk drives. In addition, three different materials are considered for the curved suspension model, and Aluminum shows the best dynamic characteristics. The proposed zoom actuator does not use a suspension supporting bobbin but a moving rail and a sloper mechanism by generating rotational force at lens holder. The sensitivity of design parameters on output performance is studied using ANSYS (3D FEM tool). Experiments using a prototype of the proposed actuator model verified the analytical prediction and performance.

• Journal of the Korean Society for Library and Information Science
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• v.35 no.2
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• pp.93-108
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• 2001

The purpose of this study was to clarify similarity and identity between university library and archives through comparison of their information materials, functions and organizations. As a results, the archives are so much similar to library in the records, functions. It means what they can use the library resources together. The archives organizations mainly belongs to museum and rarely to libraries and administration organizations.

• Journal of the Korean Society of Food Culture
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• v.27 no.1
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• pp.75-81
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• 2012

This study was conducted to investigate the physiological activity of acai berry (Euterpe oleracea Mart.) extracts from three different solvents (water, methanol, and ethanol). We measured total polyphenol and total flavonoid content, DPPH radical scavenging activity, nitrite scavenging activity, metal chelating effect, and reducing power. The extraction yield from water, methanol, and ethanol was 17.10, 9.50, and 37.51%, respectively. The highest total polyphenol content (10.54 mg/100 g) and total flavonoid contents (1.88 mg/100 g) was observed in water extract. DPPH radical scavenging activity was the highest in both water extract (72.03%) and methanol extract (74.79%) at levels of 5 mg/mL, which was similar to that of BHT (78.90%). Water extract yielded the highest metal chelating effect (92.54%) and reducing power (1.09) at levels of 5 mg/mL. Taken together, these findings suggest that extracts of acai berry can be used as functional food materials with antioxidative and nitrite scavenging activities.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.587-589
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• 2003

I. Objectives The purpose of this study was to evaluate the effects of EDTA on microhardness of roor canal dentine according to different working time. II. Materials and Methods Forty recently extracted, intact single root teeth were used. Debris and soft tissue remnants on the root surface were cleaned with scaler and stored in saline at $4^{\circ}C$ until used. All selected roots were similar in size and shape. 1. Preparation of teeth. The crown of the teeth were removed at the level of the CEJ, using a water-cooled diamond bur.(omitted)

• Journal of Drive and Control
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• v.13 no.1
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• pp.34-42
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• 2016

This study studied how the clearance, overlap and mismatch errors of spool-sleeve affect the static pressure characteristics of a servo valve. A computer simulation model was established as a direct acting servo valve and a series of simulations was conducted for various values of clearance, overlap and mismatch errors. Pressure gain decreased as the clearance increased. The overlap also affects the pressure gain and was similar to the effect of clearance. Asymmetry of the pressure plot got worse and worse as the mismatch error increased.

• Journal of Integrative Natural Science
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• v.4 no.1
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• pp.72-78
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• 2011

Morphological and anatomical characters of Amphiroa misakiensis Yendo are investigated with field materials and taxonomic accounts are given to the species. The plants grow on rocks, mussels or non-articulated corallines from the subtidal zone of Cheju island, and is characterized by recumbent and spreading habit from the substrate. The species is well defined by about 4 cm height, loosely tufted thallus with irregularly dichotomous branches, flat and irregularly broad intergeniculum in upper part, geniculum developing by cracking and sloughing of calcified cortical tissue overlying uncalcified genicular tissue, five to thirteen-tiered geniculum with unequal length, and conceptacles buried in cortices of intergeniculum. Reproductive structures in tetrasporangial, male and female plants are typical of Amphiroa. The structure and developmental patterns of conceptacles are very similar to those shown in previous studies.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.7
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• pp.667-672
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• 2004

An experimental study has been carried out to investigate the frosting behavior on the plate of thermally conductive plastic (PBT based resin) by comparing it with those of aluminum and some plastic test specimens (PTFE based resin). It is found that the frosting behavior of plastic specimens with 1 mm thickness shows similar trend to that of aluminum except PTFE. The properties of frost formed on the specimens are found to be affected by both thermal conductivity and surface characteristics of the materials. The results indicate that the heat and mass transfer rates of PBT resin are almost equivalent to those of aluminum.

• Journal of Environmental Science International
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• v.30 no.10
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• pp.833-844
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• 2021

A well-maintained landscape can increase the competitiveness of a city. Gyeongju which is the famous ancient capital of Korea, has numerous historical resources. However, the disharmony between the historical landscape and the surrounding landscape weakens the competitiveness of the city. At present, most landscape analysis methods mainly focus on plans, photos, and animation, which have certain limitations in the expression of landscape spatial scale and materials. This study aimed to use the virtual walkthrough method to take the Wolseong District of Gyeongju historical areas as the object in order to evaluate the landscape visually. Compared with planar landscape analysis methods, such as photos and videos, the virtual walkthrough method is more immersive and intuitive to experience the spatial scale. The study results revealed images, visual characteristics, and visual influence factors of the landscape, which provide essential data for the construction and improvement of landscapes in similar historical areas in the future.

• Computers and Concrete
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• v.27 no.4
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• pp.297-304
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• 2021

The hybrid Finite-Discrete Element (FDEM) approach combines aspects of both finite elements and discrete elements with fracture mechanics principles, and therefore it is well suited for realistic simulation of quasi-brittle materials. Notwithstanding, in the literature its application for the analysis of concrete is rather limited. In this paper, the proprietary FDEM code ELFEN is used to model concrete specimens under uniaxial compression and indirect tension (Brazilian tests) of different sizes. The results show that phenomena such as size effect and influence of strain-rate are captured using this modeling technique. In addition, a preliminary model of a slab subjected to dynamic shear punching due to progressive collapse is presented. The resulting fracturing pattern of the impacted slab is similar to observations from actual collapse.

• Computers and Concrete
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• v.24 no.1
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• pp.85-94
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• 2019

The ACI building code is allowing for higher strength reinforcement and concrete compressive strengths. The nominal strength of high-strength concrete columns is over predicted by the current ACI 318 rectangular stress block and is increasingly unconservative as higher strength materials are used. Calibration of a rectangular stress block to address this condition leads to increased computational complexity. A triangular stress block, derived from the general shape of the stress-strain curve for high-strength concrete, provides a superior solution. The nominal flexural and axial strengths of 150 high-strength concrete columns tests are calculated using the proposed stress distribution and compared with the predicted strength using various design codes and proposals of other researchers. The proposed triangular stress model provides similar level of accuracy and conservativeness and is easily incorporated into current codes.