• Magazine of the Korea Concrete Institute
• /
• v.6 no.2
• /
• pp.97-107
• /
• 1994

The objective of this study is to develop polymer-impregnated concrete(PIC), which is a newly developed composite material made by impregnating polymer impregnanls into hardened normal concrete, and to develop analytical techniques for its proper applications. Crystalline methyl methacrylate(MMA) is chosen as a monomer of polymer impregnants. The corrlpositions of polymer impregnants and producing processes are developed by analyzing the effects of penetration, polymerization, thermal safety, and strengthening characteristics. On t he basis of experimental results of this study, various strength characteristics and stress strain constitutive relations are formulated in terms of the compressive strength of normal concrete and the polymer loadings, which can be applied for analysis and design of PIC members. In order to provide a model for fracture analysis of flexural members, fracture toughness, fracture energy, critical crack width, and tension softening relations near crack tip are also formulated in terms of member depth, initial notch depth, and the flexural strength of normal concrete. The structural analysis procedure and the finite element computer program developed in the study are applicable to evaluate elastic behavior, ultimate strength, and tension softening behavior of MMA type PIC structural members subject to various loading conditions. The accuracy and effectiveness of the developed computer program is examined by comparing the anal ytical results with the experimental results. Therefore, it is concluded that the developed structural analysis procedure and the finite element computer program are applicable to analysis and design of in-situ and precast PIC structural members.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2012.03a
• /
• pp.54-54
• /
• 2012

전통 날염방식(Silk Screen)과 디지털날염(Digital Textile Printing)을 비교해보면, 디지털날염은 디자인에서부터 날염까지의 전공정을 완전히 디지털화함으로서 다양하게 디자인할 수 있고 미묘한 색감의 흐름을 표현할 수 있어서 자연스러운 이미지의 표현이 가능하다. 그러나 현재 디지털날염을 피혁이나 직물에 적용하기에는 프린팅속도가 느려서 생산성이 낮고 이미지 내구성(세탁, 승화, 일광, 및 마찰견뢰도)이 낮은 등 많은 단점을 가지고 있다. 또한 신발산업은 현재 중국이나 동남아시아 등 개발도상국의 등장으로 수출의 국제적 경쟁시대에 접어들면서 대량생산이나 획일적인 디자인으로부터 벗어나 고부가가치 상품을 생산해야하는 과제를 안게 되었다. 한편 가죽에 응용가능한 잉크는 크게 수성, 유성, 용제형과 자외선 경화형의 잉크가 있으며 자외선 경화형 잉크는 자외선을 이용하여 기존의 잉크의 단점을 보완한 것이다. 자외선 경화형 잉크는 자외선 램프를 열원으로 하여 이온 또는 라디칼 중합, 광중합을 하며, 에너지 소비가 적어 경제적이며 시스템 가동시 비활성 기체가 필요하지 않다. 또한 자외선 경화형 기술은 상온에서 이용할 수 있으며 잉크의 경우 건조하는 데 걸리는 시간이 필요하지 않다. 또한 시스템을 가동 시키거나 중지 시키는 것이 쉬우며 고속으로 연속적인 일을 처리할 수 있다. 프린터의 크기가 작아 공간 효율이 유리하며 용제나 $CO_2$가 발생하지 않아 친환경적인 기술이라 할 수 있다. 따라서 본 연구에서는 자외선 경화형 시스템을 잉크에 적용하여 피혁 표면에 프린팅한 다음 그 견뢰도를 측정함으로써 그 효과를 알아보았다. 세탁에 의한 Matlab 측정값으로부터 용제형 잉크의 경우는 세탁 전, 후 line width가 큰 차이를 보이나 자외선 경화형 잉크의 경우는 그 차이가 적음으로부터 자외선 경화형 잉크가 용제형에 비해 색상 탈리가 적었음을 말한다. 또한 raggedness값 역시 마찬가지 결과를 보여 안료 색소와 피혁의 접착성이 향상된 것을 알 수 있다. SEM을 이용한 피혁의 표면과 단면 사진을 보면 용제형보다 자외선 경화형 잉크를 사용한 피혁이 좀 더 매끈한 표면을 보이는데 이것은 접착기능을 하는 아크릴레이트에 의해 균일한 날염이 가능하기 때문이라 고 생각된다. 이상의 결과로부터 자외선 경화형 잉크가 세탁, 마찰, 일광 견뢰도가 우수함을 알 수 있었으며 기존의 용제형 잉크를 대체할 수 있는 좋은 재료라고 생각된다.

• Journal of Astronomy and Space Sciences
• /
• v.21 no.4
• /
• pp.233-242
• /
• 2004

The $HCO^+$ 1-0 transition line was observed toward the Sgr B2 region in our Galactic center. We found that there exist two large-scale velocity structures of $v_{lsr}\;{\sim}50\;and\;{\sim}100kms^{-1}$, which are thought to interact with each other. A new gas clump 'OF28 Cloud'('Odenwald & Fazio FIR 38' Cloud), showing different chemical and kinematical properties with the Sgr B2(M) cloud, was found in the $50kms^{-1}$ gas component. Toward the core of this component, we derive the $HCO^+$ total column density, $N(HCO^+)=(2-5){\times}10^{14}cm^{-2}$ and the mass $M=1{\times}10^6M_{\odot}$, by estimating its size, ${\sim}15pc$, from the half-power width of this component. We also found that there is a highly turbulent component in this region in the velocity range of about $100kms^{-1}$. The column density of this component is $N(HCO^+)=1{\times}10^{13}cm^{-2}$. The $HCO^+$ in this region may form effectively by the reaction between $C^+$ and OH, which are the elements whose abundances increase rapidly in shocked region.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.8
• /
• pp.545-551
• /
• 2018

For domestic application of the temperature gradient model proposed by foreign design standards, a specimen of steel box girder bridge was fabricated with the following dimensions: 2.0 m width, 2.0 m height and 3.0 m length. Temperature was measured using 24 temperature gauges during the summer of 2016. The reliability of the measured data was verified by comparing the measured air temperature with the ambient air temperature of the Korea Meteorological Administration. Of the measured gauges, four temperature gauges that can be compared with the temperature difference of the Euro code were selected and used to analyze the distribution of the measured temperatures at each point. The reference atmospheric temperature for the selection of the maximum temperature difference was determined by considering the standard error. Maximum and minimum temperatures were calculated from the four selected points and the resulting temperature difference was calculated. The model for the temperature difference in the steel box girder bridge was shown by graphing the temperature difference. Compared to the temperature distribution of the Euro code, the presented temperature difference model showed a temperature difference of $0.9^{\circ}C$ at the top and of $0.3^{\circ}$ to $0.4^{\circ}C$ at the intermediate part. These results suggested that the presented model could be considered relatively similar to the Euro code The calculated standard error coefficient was 2.71 to 2.84 times the standard error and represents a range of values. The proposed temperature difference model may be used to generate basic data for calculating the temperature difference in temperature load design.

• Journal of Korean Ophthalmic Optics Society
• /
• v.15 no.3
• /
• pp.247-255
• /
• 2010

Purpose: Developing a roofed Pechan prism type scope with long eye relief. Methods: To reduce the overall length and to lengthen the eye relief of scope, the objective part was designed by adopting the roofed Pechan prism and also the eyepiece part was designed by adopting the field lens with minus refractive power in front of reticle, respectively. Finally, by integrating above two parts, the roofed Pechan prism type scope with 90 mm eye relief was developed. Results: The characteristics of the developed and fabricated scope with 90 mm eye relief by integrating the objective part with the roofed Pechan prism and the eyepiece part with minus refractive power had the magnification of $+3.0{\times}$, the length from the 1st lens to the last lens of about 121 mm, the barrel diameter of 28 mm, and the effective objective-diameter of 17 mm. Also it was found that the line width of resolution was about 900 cycles/rad at the 50% MTF value criterion. Conclusions: We could design and manufacture the roofed Pechan prism type scope with 90 mm eye relief, the characteristics of which had the magnification of $3.0{\times}$, the MTF above 50% at 900 cycles/rad, and the length from the 1st lens to the last lens of about 121 mm.

• Journal of Satellite, Information and Communications
• /
• v.3 no.1
• /
• pp.41-47
• /
• 2008

Line-of-sight communications cannot easily support korean armed forces because of mountainous terrain. ADD(Agency for Defense Development) introduced ANASIS(Army Navy Air-force Satellite Information System) to meet the Korean warfighter's operational needs. Currently, army's military satcom terminal is designed for either fixed site or on-the-pause operation. The US army is under development of multi-band integrated on-the-move satellite terminals to let the army's communication capability to keep pace with globally deployable Joint Task Force for network-centric application. In this paper we analyzed X-band and Ka-band link and subsystem requirement. Our focus here is to describe key technical issues. Especially, On the basis of 3dB beam width of 0.9m antenna, Tracking accuracy and disturbances compensation signal processing on-the-move of Antenna Tracking system is analyzed. Also, protocol is analyzed that minimize blockage on the move due to an obstacle. when the received signal blocked, it stop to transmit burst signal and retransmit when blockage removed through received synchronization signal monitoring. Analyzed specification will be used to make prototype terminal to analyze risk for mass production

• Journal of KIISE:Databases
• /
• v.34 no.4
• /
• pp.343-356
• /
• 2007

Due to advances in position monitoring technologies such as global positioning systems and sensor networks, recent position information of moving objects has the form of streaming data which are updated continuously and rapidly. In this paper we propose an efficient trajectory maintenance method that stores the streaming position data of moving objects in the limited size of storage space and estimates past positions based on the stored data. For this, we first propose a new concept of incremental extraction of position information. The incremental extraction means that, whenever a new position is added into the system, we incrementally re-compute the new version of past position data maintained in the system using the current version of past position data and the newly added position. Next, based on the incremental extraction, we present an overall framework that stores position information and estimates past positions in the stream environment. We then propose two polynomial-based methods, line-based and curve-based methods, as the method of estimating the past positions on the framework. We also propose three incremental extraction methods: equi-width, slope-based, and recent-emphasis extraction methods. Experimental results show that the proposed incremental extraction provides the relatively high accuracy (error rate is less than 3%) even though we maintain only a little portion (only 0.1%) of past position information. In particular, the curve-based incremental extraction provides very low error rate of 1.5% even storing 0.1% of total position data. These results indicate that our incremental extraction methods provide an efficient framework for storing the position information of moving objects and estimating the past positions in the stream environment.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.4
• /
• pp.39-47
• /
• 2006

This study long jump action to each situation on a chessboard and section of sight disabled person and normal person through third dimension reflex analysis mechanical special quality because do comparative analysis sight disabled person's exercise ability and technology structure of action that run understand. As can do better without danger of injury map and training of exercise item that action that run is included, do offer of pabulum by purpose. Through this study, conclusion is as following. 1. Sight disabled persons' long jump average recording (121.84cm) showing normal persons' average recording (259.27cm) and much differences, show that motion of body is not big to Touch-down from Ready action. 2. Each phase body center composition(r) average speed displayed result that it is more meaning more than Each phase time required. 3. Began in line carriage without body back stretching in 1 situation on Event one are sight disabled persons. Was expose that do not bend enough knee and ankle than normal person in Event two. Was expose that body is not drooped for surface of land in Event three, and knee and ankle were expose that do not unfold easily than normal person. Was expose that do not bend enough on Touch-down knee by relation that can not grasp position of the floor in Event four. 4. When taking off, the average of horizontal speed of body center are 1.80m/sec for blind people and 3.53m/sec for the normal. In this connection, the study shows that the difference of horizontal speed between the blind and the normal is bigger than difference of vertical speed, which are 1.56m/sec for the blind and 1.98m/sec for the normal. Also, composite speed also shows us big difference between 2.41m/sec of the blind and 4.07m/sec of the normal. The speed body center of take-off was expose that average adjuster are big width of deceleration than average - beginning disabled person's average by 2.23m/sec - 1.71m/sec in the vertical speed. 5. If examine change of high and low for z Sign of right hand, change of high and low showed as is small than normal person is sight obstacle, and all hand movements are small and was expose that do not use enough reaction of body as well as in ready action.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.38 no.4
• /
• pp.231-239
• /
• 2012

Objectives: This study sought to provide guidelines in order to decrease the incidence of nerve injury during mandibular ramus bone harvesting, and to improve understanding of the anatomical structure of the inferior alveolar canal (IAC) to include its distance from the exterior buccal cortex. Materials and Methods: In January and February 2009, 20 patients who visited the Wonkwang University Department of Oral and Maxillofacial Surgery reporting various conditions underwent cone beam computed tomography and were included in this study. Patients with missing left or right mandibular first molars or incisors, or who had jaw fracture or bone pathologies, were excluded. The reference point (R point) was defined as the point where the occlusal plane reached the anterior ramus of the mandible. The position of the IAC in relation to the R point, the buccal bone width (BW), the alveolar crest distance (ACD), the distance from the alveolar crest to the occlusal plane (COD), and the distance from the IAC to the sagittal plane (CS) were determined using proprietary image analysis software which produced cross-sectional coronal and axial images. Results: The distance medially from the R point to the IAC along the axial plane was $6.19{\pm}1.21mm$. The HD from the R point, posteriorly to IAC, in the lateral view was $13.07{\pm}2.45mm$, the VD from the R point was $14.24{\pm}2.41mm$, and the ND from the R point was $10.12{\pm}1.76mm$. The pathway of the IAC was positioned almost in a straight line along a sagittal plane within $0.56{\pm}0.70mm$. The distance from the buccal bone surface to the IAC increased anteriorly from the R point. Conclusion: Marking osteotomy lines in the retromolar area in procedures involving bone harvesting should be discouraged due to the risk of damage to IAC structures. Our measurements indicated that the area from the R point in the ramus of the mandible to 10 mm anterior can be safely harvested for bone grafting purposes.

• Journal of the Korean Magnetics Society
• /
• v.10 no.3
• /
• pp.123-132
• /
• 2000

Cerium substituted YIG thin films were grown by rf magnetron sputter techniques. We investigated the effects of post-deposition heat-treatment as well as various deposition parameters such as substrate materials, substrate temperature. sputter power, and sputter gas types on the crystallinity, chemical composition, microstructure and magnetic characteristics of the films. Post-deposition heat treatment over 750 $\^{C}$ was applied to crystallize as-prepared amorphous films, and a strong tendency of particular crystallographic planes tying parallel to substrate surface was observed for the post-deposition heat-treated films on GGG substrate. The chemical composition of the films exhibited a wide range of chemical stoichiometry depending on the oxygen fraction of sputter gas, and in particular the composition of the film deposited in sputter gas with an oxygen fraction of R = 10% was Ce$\_$0.23/Y$\_$1.30/Fe$\_$3.50/O$\_$12/. With raising the temperature of post-deposition heat-treatment from 900 $\^{C}$ to 1100 $\^{C}$, the surface roughness of the film on GGG substrates increased from about 3 nm to 40 nm, but their coercive force and ferromagnetic resonance line width decreased from 0.477 kA/m to 0.369 kA/m and from 12.5 kA/m to 8.36 kA/m, respectively.