• 방사선산업학회지
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• 제9권1호
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• pp.9-13
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• 2015

Epoxy resin is widely used as aerospace, automobile, construction and electronics due to their good mechanical and electrical properties and environmental advantages. However, the inherent flammability of epoxy resin has limited its application in some field where good flame retardancy is required. Nano clay can enhance the properties of polymers such as flames retardancy and thermal stability. In this study, we have investigated the nanoclay filled epoxy composite, which has good flame retardancy while maintaining high mechanical properties. The cured epoxy resins were obtained using an electron beam curing process. The nano clays were dispersed in epoxy acrylate solution and mechanically stirred. The prepared mixtures were irradiated using an electron beam accelerator. The composites were characterized by gel content and thermal/mechanical properties. Moreover, the flammability of the composite was evaluated by limited oxygen index (LOI). The flame retardancy of nano clay filled epoxy composite was evidently improved.

• 디지털융복합연구
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• 제11권2호
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• pp.257-262
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• 2013

급격히 변모 발전하고 있는 모바일 시장에서 근거리 무선 통신인 Near Field Communication은 스마트 환경의 화두로 떠오르고 있다. 이러한 NFC 기술을 구글 사에서는 Android 플랫폼에 도입하여 전자 결제 시장에서 주도권을 확보하고 있으며 국내를 비롯한 많은 국가 들이 이동통신사와 금융계의 연계로 서비스 개발과 기술 발전에 박차를 가하고 있다. 이러한 환경에서 주목할 만한 이슈 중 하나가 NFC 서비스의 안정성 확보이다. Android 플랫폼은 모바일 디바이스의 운영체제로서 제한된 하드웨어와 즉각적인 응답성이 요구되는 소프트웨어 스택이다. 하지만 제한적인 하드웨어의 특성에 적합한 구조적 특징으로 인하여 실시간 처리에 있어서 안정적인 응답성이 보장되지는 못하고 있다. 따라서 본 논문은 Android 플랫폼에서 제공하고 있는 실시간 처리 영역을 분석하고 이를 NFC Application에 적용하여 보다 안정적인 데이터 처리와 응답성을 확보를 위한 연구를 하고자 한다.

• 영어영문학
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• 제57권1호
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• pp.73-105
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• 2011

The purpose of this paper is to contend the importance of resurrection of fluid identity and ecological imagination for making the habitable biosphere in Marilynne Robinson's Housekeeping. Ruth as a narrator suggests the future-oriented vision that the environment and nature(mother) can be resurrected, crossing Fingerbone bridge of the boundary line of society/nature as a faithful follower of her aunt Sylvie and becoming the existence with a transparent voice despite of her absence. This novel is to rewrite the American pastoral. Based on the patriarchical way despite of the absence of Edmund Foster, Sylvia's conventional housekeeping is to divide between inside and outside of the house. Nevertheless, Sylvia's relentless efforts to keep her house intact turns out to be fragile. Contrasting with Sylvia, Sylvie's housekeeping is to recognize the continuity of inside and outside. She willingly accepts the reconciliation of the self, the nature and the society. After Ruth and Lucille's staying at night in the lake, they are diverged into going their own way. Ruth accepts Sylvie as a substitute mother. Lucille leaves the house voluntarily and go to her Home Economics teacher, Miss Royce, pursuing the ideal mother of symbolic society. Sylvie and Ruth has the more intimate bond, with their trip to the deserted house in the valley. Ruth meditates on the non-solidity of house and the resurrection of her family. Leaving their house to escape from the town people's legal enforcement, Sylvie and Ruth become transients. Although their history is completed by the drown-death publicly, they always want to visit Lucille's well kept house in Fingerbone. Therefore the method for making Ruth and Sylvie as the existences of ecological imagination return to the real world is to accept the reconciliation of nature and society. This novel is not limited as the binary opposition of vagrance/stability and transience/durability. The significant element of fluid identity can be composed of the interactions with transience and stability.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.690-699
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• 2008

In this paper a conventional approach for design and analysis of subsonic air vehicle is used. First of all subsonic aerodynamic coefficients are calculated using Computational Fluid Dynamics(CFD) tools and then wind-tunnel model was developed that integrates vehicle components including control surfaces and initial data is validated as well as refined to enhance aerodynamic efficiency of control surfaces. Experimental data and limited computational fluid dynamics solutions were obtained over a Mach number range of 0.5 to 0.8. The experimental data show the component build-up effects and the aerodynamic characteristics of the fully integrated configurations, including control surface effectiveness. The aerodynamic performance of the fully integrated configurations is comparable to previously tested subsonic vehicle models. Mathematical model of the dynamic equations in 6-Degree of Freedom(DOF) is then simulated using MATLAB/SIMULINK to simulate trajectory of vehicle. Effect of altitude on range, Mach no and stability is also shown. The approach presented here is suitable enough for preliminary conceptual design. The trajectory evaluation method devised accurately predicted the performance for the air vehicle studied. Formulas for the aerodynamic coefficients for this model are constructed to include the effects of several different aspects contributing to the aerodynamic performance of the vehicle. Characteristic parameter values of the model are compared with those found in a different set of similar air vehicle simulations. We execute a set of example problems which solve the dynamic equations to find the aircraft trajectory given specified control inputs.

• 한국동물생명공학회지
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• 제37권2호
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• pp.96-105
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• 2022

The ovary undergoes substantial physiological changes along with estrus phase to mediate negative/positive feedback to the upstream reproductive tissues and to play a role in producing a fertilizable oocyte in the developing follicles. However, the disorder of estrus cycle in female can lead to diseases, such as cystic ovary which is directly associated with decline of overall reproductive performance. In gene expression studies of ovaries, quantitative reverse transcription polymerase chain reaction (qPCR) assay has been widely applied. During this assay, although normalization of target genes against reference genes (RGs) has been indispensably conducted, the expression of RGs is also variable in each experimental condition which can result in false conclusion. Because the understanding for stable RG in porcine ovaries was still limited, we attempted to assess the stability of RGs from the pool of ten commonly used RGs (18S, B2M, PPIA, RPL4, SDHA, ACTB, GAPDH, HPRT1, YWHAZ, and TBP) in the porcine ovaries under different estrus phase (follicular and luteal phase) and cystic condition, using stable RG-finding programs (geNorm, Normfinder, and BestKeeper). The significant (p < 0.01) differences in Ct values of RGs in the porcine ovaries under different conditions were identified. In assessing the stability of RGs, three programs comprehensively agreed that TBP and YWHAZ were suitable RGs to study porcine ovaries under different conditions but ACTB and GAPDH were inappropriate RGs in this experimental condition. We hope that these results contribute to plan the experiment design in the field of reproductive physiology in pigs as reference data.

• PNF and Movement
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• 제19권1호
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• pp.43-55
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• 2021

Purpose: The purpose of this study was to determine the effects of contract relaxation and a combination of isotonics in proprioceptive neuromucular facilitation (PNF) on hip and lumbopelvic motions of male patients with chronic low back pain. Methods: As the subjects of this study, a total of 45 male patients with chronic low back pain were divided into groups: 15 who underwent contract relaxation (CR) of the PNF of their hip joints, 15 who underwent a combination of isotonics (CI) of the PNF, and 15 who underwent both techniques. A device for analyzing three-dimensional motion was used to measure hip medial rotation angles, lumbopelvic rotation angles, and hip medial rotation angles at the start of lumbopelvic rotation during hip medial rotation. A two-way repeated measures ANOVA was used to compare the average values. Results: There were interactions in the hip medial rotation angles, lumbopelvic rotation angles and hip medial rotation angles at the start of lumbopelvic rotation based on the methods and periods of exercise (p < 0.05). The CR and the CR+CI groups displayed more increased hip medial angles when compared to the CI group. The CR+CI group had more decreased lumbopelvic rotation angles when compared to the CR and the CI groups. The CR+CI group had more increased hip medial rotation angles at the start of lumbopelvic rotation when compared to the CR and the CI groups. Conclusion: It can be concluded that the combination of stretching and stability exercises was effective in male patients with chronic low back pain who showed limited hip medial rotation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제35권6호
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• pp.442-450
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• 2009

Purpose: Simultaneous implantation has been traditionally limited to patients with at least 5 mm of residual bone to ensure that the implant is completely stabilized. This is considered to be one of the most critical factors for primary implant stability and parallelism and, subsequently osseointegration. Recently, improved initial implant stability is provided by advancement of surgical techniques, implant designs and surface treatments. This has led surgeons to extending simultaneous treatment option to patients with below 4 mm of residual bone height, despite the lack of much data. The purpose of this study was to retrospectively evaluate and compare the status of implants which are installed by delayed and simultaneous methods. Material and methods: The subjects were patients(121 patients, 278 implants) who had been operated with sinus lifting from 2003 to 2007 in Sun Dental Hospital. Lateral window approach with autograft and xenograft(1:1 ratio) were carried out for all sinus lifting. 4 types of implant were used. The mean follow up period was 26.3 months(19 - 58 months) in delayed group, and 22.8 months(18 - 43 months) in simultaneous group. Results: The survival rate of implant restoration of this study was 98.2% in delayed group and 91.7% in simultaneous group. In simultaneous group, wide-platform type implants showed 100% survival rate. The total average of marginal bone loss in radiographs was $0.96\;{\pm}\;0.29\;mm$ in delayed group and $1.02\;{\pm}\;0.31\;mm$ in simultaneous group. Conclusion: Simultaneous implantation with sinus lifting(below 4mm of residual bone height) could be predictable treatment.

• 지질공학
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• 제21권3호
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• pp.247-257
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• 2011

본 연구는 사면재해 취약성 평가를 위해 사면모델 중 하나인 무한사면 해석모델을 적용하였다. 그러나 무한사면 해석모델은 광역적인 연구지역에 적용하는데 있어서 데이터획득 및 처리과정에 어려움이 있고 데이터 획득과정에서 불가피하게 불확실성이 개입되는 문제가 있다. 이러한 불확실성을 최소화하기 위해 확률론적 해석기법인 몬테카를로 시뮬레이션을 적용하였으며, 광역적인 연구지역에 무한사면 해석모델을 적용하기 위하여 GIS를 활용한 무한사면 안정해석법으로 파괴확률을 획득하였다. 연구지역으로는 사면재해가 집중적으로 발생한 보은지역을 선정하였고 사면의 기하학적인 특성과 점착력 및 내부마찰각 등의 강도정수를 획득하였다. 또한 불확실성의 효과를 평가하기 위해 강도정수의 변동계수를 10%에서 30%로 고려하였고 이러한 과정을 통하여 확률론적 해석기법은 자료의 불확실성을 감쇠시킬 수 있다는 결과를 도출하였다.

• 한국환경복원기술학회지
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• 제14권4호
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• pp.41-54
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• 2011

Tree roots can enhance soil shear strength and slope stability. However, there has been a limited study about root reinforcement of major tree species in Korea because of some experimental difficulties. Thus, this study was conducted to analyze the performance of Japanese larch (Larix kaempferi) and Korean pine (Pinus koraiensis) which are two common plantation species in Korea. Profile wall method was used to measure the spatial distribution of root system and its diameter within 15 soil walls of Japanese larch stand and 13 soil walls of Korean pine stand in Taehwa University Forest, Seoul National University, Korea. Root tensile properties of each species were assessed in the laboratory, and root reinforcements were estimated by Wu model. The study observed that the number and cross-sectional area (CSA) of root in both species could tend to decrease with soil depth. Especially, CSA were well-fitted to exponential functions of soil depth. Mean root area ratios (RAR) were 0.03% and 0.10% for Japanese larch and Korean pine, respectively. Estimated root reinforcement from Wu model were, on the average, 4.04 kPa for Japanese larch and 12.26 kPa for Korean pine. Overall, it was concluded that root reinforcement increased the factor of safety (Fs) of slope for small-scale landslide as the result of two-dimensional (2-D) infinite slope stability analysis considering vegetation effects.

• 대한통합의학회지
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• 제9권4호
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• pp.71-83
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• 2021

Purpose : This study compared the differences in power and agility of athletes in each sports using visual response speed test (VRST) scores after conducting 10 weeks of body stability exercise (BSE) on elementary school athletes in handball, football, volleyball and conducted a post-hoc test on the measured values. The subjects of this study were baseball (n=27), taekwondo (n=22), and football (n=23) athletes with at least two years of athletic experience. A total of 72 elementary school athletes were measured by VRST after 10 weeks of BSE under the same conditions. Methods : For VRST measurement of the upper extremity, the right and left hands were alternately touched in the order the blazepod equipment lights were turned on. The number of touches for 15 seconds and response touch were measured. In the case of the measurement of lower extremity the left lower extremity was measured first when the Blaze pod equipment light came on. The average value was obtained by measuring 3 times using a measurement sensor with the position indicated in order to measure the upper arms and legs the same. Results : This study confirmed homogeneity among sports and that VRST improved after implementing BSE for sports. However, no statistically significant difference was identified when comparing VRST improvements between sports, and post-hoc test results showed no significant differences either. Conclusion : After applying the BSE program under the same conditions for 10 weeks to elementary school students who can improve their power and agility the most, the results of the examination using the Blaze pod showed that the power and agility of baseball, taekwondo, and soccer players were similarly improved. From the fact that there was no significant difference among sports, it could be inferred that the BES training program could improve VRST without being limited to some sports.