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        검색결과 685

        241.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목 적: 성인과 아동에서 굴절이상 정도와 안광학 상수 간에 상관성이 감소하는 시점을 알아보고자 하였 다. 방 법: 청주에 거주하는 194명(성인 116명, 아동 78명)을 대상으로 자동굴절력계와 안구계측기로 굴절검 사와 안광학 상수를 측정하였다. 각막곡률반경과 전안방 깊이는 전안부 안광학 상수로, 안축장은 후안부 안 광학 상수로 이용하였다. 전안부와 후안부의 통합된 안광학 상수인 안축장 대 각막곡률반경의 비(AL/CR ratio)와 굴절이상 정도의 관련성을 제시하였다. 각 안광학 상수와 굴절이상 정도와의 관련성을 확인한 후 안축장에 따라 안광학 상수 간의 상관성이 없어지는 값을 찾고, 이를 등가구면굴절력으로 제시하였다. 결 과: 성인과 아동에서 굴절이상 정도와 안광학 상수들 간의 상관관계는 안축장과 각막곡률반경을 각각 적용하였을 때 보다 안축장 대 각막곡률반경비(AL/CR ratio)로 나타날 때 설명력이 높았다(아동 그룹 r2=0.681, p=0.000, 성인 그룹 r2=0.723, p=0.000). 성인과 아동에서 전안부와 후안부의 안광학 상수 사이 에 상관성이 없어지는 안축장의 길이를 찾았다. 아동에서 각막곡률반경과 안축장의 상관성은 안축장 24 mm 를 기준으로(r=-0.174, p=0.238), 전안방 깊이와 안축장은 25 mm를 기준으로(r=-0.153, p=0.585) 안축장 이 길어질 때 상관성이 없어지는 것으로 나타났다. 성인에서 각막곡률반경과 안축장의 상관성은 24.5 mm를 기준으로, 전안방 깊이와 안축장은 26.0 mm를 기준으로 안축장이 길어질 때 상관성이 없어지는 것으로 나 타났다(r=0.178, p=0.083, r=0.054, p=0.796). 기준점이 되는 각 안축장 값을 등가구면굴절력으로 나타냈 을 때 아동에서 24 mm는 약 -1.30D, 25 mm가 약 -3.20D로 나타났고(r2=0.609) 성인에서 안축장 24.5 mm가 약 -2.10D, 26 mm가 약 –4.30D로 나타났다(r2=0.450). 결 론 안광학 상수 간의 상관성은 정시를 벗어나 어느 정도 비정시가 된다 하더라도 지속적인 상관관계 를 나타낸다. 따라서 정시화는 특정 나이나 시력에 대한 기존의 기준과 더불어 지속적 연구를 통해 안광학 상수 간의 상관성 유무에 대한 고려도 함께 이루어져야 할 것이다.
        4,200원
        242.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        제주마 경주 능력 개량을 위한 기초 자료 확보를 위하여 혈통 정보량과 오류량이 유전 모수 추정에 미치는 영향을 분석하였다. 혈통 자료는 램덤으로 혈통 정보의 삭제(0~25%) 또는 오류 유발(0~25%)과 각 수준별 20회 반복으로 모의자료를 형성하였다. 분석에 이용된 형질은 제주마 1,000m 경주의 주파 시간을 이용하였고, 상가적 유전 분산의 추정은 DF-REMLAI 알고리즘을 이용하였다. 개체의 양부모에 대한 정보 유실량과 오류량의 증가는 선형적인 회귀관계로 상가적 유전 분산 성분(유실 b = -0.079, 오류 b= -0.114)과 유전력 추정치(유실, b= -0.006; 오류, b = 0.008)의 감소를 초래했다(p<0.01). 특히 개체의 양부모에 대한 정보유실보다는 정보 오류가 상가적 유전분산량과 유전력 추정치를 보다 크게 왜곡하는 것으로 나타났다. 부 또는 모에 대한 정보의 유실과 오류의 증가도 대부분 오차 분산 성분과 영구 환경 분산 성분의 증가를 유발시키고, 상가적 유전 분산성분의 감소를 가져왔다. 원자료에서 얻은 모수를 기준으로 했을 때 양부모에 대한 정보의 유실량과 오류량이 1% 증가함에 따라 유전력은 각각 0.92% 및 1.39%씩 낮아지는 관계를 보였다 (p<0.01). 제주마의 1,000m 주파 속도에 대한 유전력은 0.60으로 추정되었지만, 초기 집단에 존재하는 혈통 정보의 누락 및 오류를 고려한다면 실제보다도 10% 정도는 낮게 추정되고 있다고 사료되었다. 이와 같은 결과는 상가적 유전 분산량의 감소는 물론, 선발에 따른 제주마의 경주 능력에 대한 유전적 개량량에도 영향을 줄 것으로 판단된다.
        4,000원
        243.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The source parameters of four earthquakes with magnitude larger than 4.0 nearby the offshore Sinan are analyzed. The waveform inversion method is used for analyzing the source parameters of two events (20 August 2012 and 21 April 2013) with C&B and AK135-c crustal velocity structure models. The source parameters of the other two events (26 July 1994 and 23 March 2003) are obtained from references. Focal mechanisms of the events are strike slip faulting or strike slip faulting with a thrust component. The directions of P-axes of the events are ENE-WSW or NE-SW which are similar to previous studies on P-axes in and around the Korean peninsula. With regard to the events nearby the offshore Sinan, the regional stress, rather than being local stress, is seen to be the result of the combination of tectonic forces from the compression of plates colliding to the Eurasian Plate.
        4,000원
        244.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study is focused on investigating the relation between the particle size of silver flake powder and mechanical milling parameters. Mechanical milling parameters such as ball size, impeller rotation speed and milling time of the attrition ball-mill were controlled to produce silver flake powder. The particle size of the silver flake powder increased with increasing ball size and impeller rotation speed. The change of the particle size of the silver flake powder with mechanical milling parameters was analyzed based on balls motion in the mill container of the attrition ball-mill. The silver flake particles were formed at the elastic deformation area of the ball due to the collision between balls. The change of the particle size of the silver flake powder with mechanical milling parameters well consists with the change of the collision energy of ball with parameters mentioned above.
        4,000원
        245.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        한국 재래돼지(KK) 69두 및 재래돼지 모돈과 듀록종 웅돈의 교배를 통하여 생산된 교잡종(KD) 88두 로부터 조사된 체중측정 기록에 대해 세 가지 비선형 성장곡선을 적용하여 KK(Korean Native Sow × Korean Native Boar) 및 KD(Korean Native Sow × Duroc Boar)의 성장모형을 추정하고, 추정된 성 장모형의 모수를 이용하여 KK와 KD에 대한 성장특성에 대한 기초자료를 제공하고자 실시하였다. 각각의 성장곡선 함수로 추정한 성장곡선은 다음과 같다. von Bertalanffy 모형의 경우 KK의 암컷, 수컷, KD의 암컷 및 수컷의 모형은 각각 , 및 로 추정되었다. Gompertz 모형의 경우 KK의 암컷, 수컷, KD의 암컷 및 수컷의 모형은 각각 ,, 로 추정되었다. Logistic 모형의 경우 KK의 암컷, 수컷, KD의 암컷 및 수컷의 모형은 각각 , , 및로 추정되었다. von Bertalanffy 모형의 경우 최대성장시기를 나타내는 변곡점()은 KK 암컷집단과 수컷집단에서 각각 4.40±0.12개월령 및 4.86±0.22개월령으로 추정되었고, KD 암컷 및 수컷집단에서는 각각 3.81±0.09개월령 및 4.00±0.08개월령으로 추정되었다. Gompertz 모형의 경우 는 KK암수 및 KD암수에 대해 각각 4.32±0.11개월령, 4.90±0.12개월령, 4.03±0.69개월령 및 4.11±0.06개월령으로 나타났다. Logistic 모형의 경우 는 KK암수 및 KD 암수에 대해 각각 4.18±0.07개월령, 4.41±0.05개 월령, 4.00±0.06개월령 및 4.03±0.04개월령으로 나타났다. 오차 평균 제곱합의 결과를 보면, KK의 성장은 Logistic, Gompertz 그리고 von Bertalanffy 모형 순으로 적합도가 좋은 것으로 판단되며, KD는 Gompertz, Logistic 그리고 von Bertalanffy 모형 순으로 적합도가 좋은 것으로 판단된다.
        4,000원
        246.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 시험은 효소제 및 효모추출물 급여가 사양성적, in vitro 반추위 발효 및 혈액성상에 미치는 영향을 구명하기 위해 23개월령의 한우 거세우 48두를 공시하여 사료용 첨가제로 농후사료의 0.1% 수준으로 급여하여 출하시까지 대조구(무첨가), 처리구 1(효소제), 처리구 2(효모추출물), 처리구 3(효소제+효모추출물)으로 구분하여 급여하였다. 사양성적에서는 급여 4개월과 8개월의 일당증체량과 사료요구율이 처리구 1에서 가장 향상되었고 (p<0.05), 대조구에서 가장 낮았다(p<0.05). 도축성적에서는 육량지수를 포함하여 처리구 1>처리구 3>처리구 2>대조구 순으로 나타났다. in vitro 배양액에 따른 처리구별 pH는 대조구>처리구 2>처리구 3>처리구 1 순으로 유의적(p<0.05)인 차이를 나타냈고, VFA와 사료소화율은 처리구 1과 3에서 높았고 (p<0.05), 대조구에서는 낮았다(p<0.05). 혈액성상에서는 면역 첨가제 급여군인 처리구 2와 3에서 급여기간에 따른 백혈구 수치가 유의적(p<0.05)으로 감소하였는데, 이는 면역글로블린 G의 유의적(p<0.05)인증가에 따라서 상대적으로 나타난 것으로 판단된다. 결과적으로, 한우 비육후기 거세우의 사료첨가제 급여 시험에서 처리구 1은 급여 4개월부터 대조구 대비 사양성적 및 도체성적을 향상시켰고, 처리구 2는 급여 2개월부터 면역에 관련된 면역글로블린 G의 혈액성상을 개선시키는 것으로 분석되었다.
        5,200원
        247.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 2006년부터 2011년까지 6년동안 전남 영광소재 N종돈장에서 검정된 23,213두의 산육형질을 활용하여 유전모수 및 유전적 추세를 추정하므로서 돼지 개의 기초자료로 활용하기 위하여 실시하였다. 본 연구에서 추정한 유전모수는 다형질 개체모형을 이용하여 추정하였다. 본 연구에서 추정한 품종별 성장형질에 대한 유전력의 범위를 살펴보면, 일당증체량은 0.30~0.31로 추정되었고, 등지방두께는 0.39~0.60 및 90kg 도달일령은 0.37~0.45로 추정되었다. 일당증체량과 등지방두께 및 90kg 도달일령의 유전상관의 품종별 범위는 각각 -0.07~0.13과 -0.98~-0.90으로 추정되었다. 등지방두께와 90kg도달일령은 -0.16~0.04로 추정되어 저도의 상관도를 보였다. 특히 일당증체량과 등지방두께는 2009년 이후에 태어난 개체들이 증가하는 경향을 보였고, 90kg도달일령은 감소하는 경향을 보였다.
        4,000원
        248.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objectives of this study were to estimate genetic parameters for 10 linear conformation traits and final score in Hanwoo cows. A total of 53,277 records for type traits of Hanwoo cows were collected from 2008 to 2012 from Korea Animal Improvement Association. Ten linear traits studied were stature, body length, chest depth, body rump angle, rump length, pin bone width, udder volume, foot angle, rear legs side view, and rear legs rear view. The model included the fixed effects of herd-year-classifier, age at measurement and age after calving, the random animal additive genetic effect and residual effect. Heritability estimates for linear type traits were ranged from 0.003 for rear legs side view to 0.213 for final score. Genetic correlations among linear type traits were ranged from -0.068 (for rear legs side view and rear legs rear view) to 0.982 (for body length and rump length). The final score was found to be in a strongest genetic correlation with rear legs rear view (0.947), followed by pin bone width (0.918), body length (0.887), rump length (0.883), chest depth (0.883), udder volume (0.811), stature (0.802), rump angle (0.637), foot angle (0.519) and rear legs side view (0.176). Corresponding phenotypic correlations for pairs of linear type traits were mostly similar in direction, but smaller than the genetic correlations.
        4,000원
        249.
        2014.06 구독 인증기관 무료, 개인회원 유료
        목포해역에서 염분의 농도는 우기인 여름철을 제외한 나머지 계절에서는 30.3%에서 31.1%의 범위를 나타내고 있으나 여름철에는 27.6% 로 낮아져 담수의 유입이 많았다는 것을 알 수 있다. 8월 영산호 하구언 직 하류에서 염분의 농도는 23.6% , 목포항에서는 23.4%이였으며 장좌도와 달리도에서는 28.9%, 30.7%로 나타나 담수의 유입이 영산호에 유입되었으며 목포항에서도 혼합되지 않고 있으며 오히려 염도가 약간 낮아진 것으로 보아 목포항의..
        4,000원
        250.
        2014.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Due to their unique properties, tungsten borides are good candidates for the industrial applications where certain features such as high hardness, chemical inertness, resistance to high temperatures, thermal shock and corrosion. In this study, conditions were investigated for producing tungsten boride powder from tungsten oxide(WO3) by self-propagating high-temperature synthesis (SHS) followed by HCl leaching techniques. In the first stage of the study, the exothermicity of the WO3-Mg reaction was investigated by computer simulation. Based on the simulation experimental study was conducted and the SHS products consisting of borides and other compounds were obtained starting with different initial molar ratios of WO3, Mg and B2O3. It was found that WO3, Mg and B2O3 reaction system produced high combustion temperature and radical reaction so that diffusion between W and B was not properly occurred. Addition of NaCl and replacement of B2O3 with B successfully solved the diffusion problem. From the optimum condition tungsten boride(W2B and WB) powders which has 0.1~0.9 um particle size were synthesized.
        4,000원
        251.
        2014.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Probabilistic tsunami hazard analysis (PTHA) is based on the approach of probabilistic seismic hazard analysis (PSHA) which is performed using various seismotectonic models and ground-motion prediction equations. The major difference between PTHA and PSHA is that PTHA requires the wave parameters of tsunami. The wave parameters can be estimated from tsunami propagation analysis. Therefore, a tsunami simulation analysis was conducted for the purpose of evaluating the wave parameters required for the PTHA of Uljin nuclear power plant (NPP) site. The tsunamigenic fault sources in the western part of Japan were chosen for the analysis. The wave heights for 80 rupture scenarios were numerically simulated. The synthetic tsunami waveforms were obtained around the Uljin NPP site. The results show that the wave heights are closely related with the location of the fault sources and the associated potential earthquake magnitudes. These wave parameters can be used as input data for the future PTHA study of the Uljin NPP site.
        4,000원
        253.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper shows the feasibility on the application of E-glass fiber/epoxy(GFRP) composite materials to an automotive leaf spring. In order to keep much lighter weight by replacing the steel with the composite material, it is important to optimize the material parameters and design variables consisting of the structure. This paper focused on the effects of material compositions and its fiber orientations for estimating the static behaviors of leaf spring. First of all, basic material properties of GFRP composite were measured by five types of coupon specimens from ASTM standard test. The reverse implementation was also done to obtain the complete set of in-situ fiber and matrix properties from ply test results. Finally, the static spring rates was examined for the variation of thickness and material parameters such as fiber angles and resin contents of composite leaf spring.
        4,000원
        254.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the immediate effect of fabric ankle-foot orthosis on spatiotemporal gait parameters, compared to a barefoot condition in children with spastic cerebral palsy. Eleven children with spastic cerebral palsy participated in this study. Spatiotemporal gait parameters were measured with the GAITRite system. Fabric ankle-foot orthosis significantly improved Timed Up and Go test time and gait velocity. There was no significant difference in cadence. The step time significantly improved in both the more and less affected foot compared to the barefoot condition. The step length of the affected foot also significantly improved, but there was no significant difference in the step length of the less affected foot. There was significant improvement in the stride length of both the affected and less affected foot, but no significant difference in single stance or double stance. The fabric ankle-foot orthosis could improve stability, and selective control of the joint and promote better walking in children with cerebral palsy. Consequently, the fabric ankle-foot orthosis might be an alternative assistive device for neurological populations as a primary role instead of the typical ankle-foot orthosis.
        4,000원
        255.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES: Evaluation of input parameters determination procedure for dynamic analysis of aggregates in DEM. METHODS: In this research, the aggregate slump test and angularity test were performed as fundamental laboratory tests to determine input parameters of spherical particles in DEM. The heights spreads, weights of the simple tests were measured and used to calibrate rolling and static friction coefficients of particles. RESULTS : The DEM simulations with calibrated parameters showed good agreement with the laboratory test results for given dynamic condition. CONCLUSIONS: It is concluded that the employed calibration method can be applicable to determine rolling friction coefficient of DEM simulation for given dynamic conditions. However, further research is necessary to connect the result to the behavior of aggregate in packing and mixing process and to refine static friction coefficient.
        4,000원
        256.
        2014.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A microstructure analysis is carried out to optimize the process parameters of a randomly oriented discrete length hybrid carbon fiberreinforced carbon matrix composite. The com-posite is fabricated by moulding of a slurry into a preform, followed by hot-pressing and carbonization. Heating rates of 0.1, 0.2, 0.3, 0.5, 1, and 3.3°C/min and pressures of 5, 10, 15, and 20 MPa are applied during hot-pressing. Matrix precursor to reinforcement weight ra-tios of 70:30, 50:50, and 30:70 are also considered. A microstructure analysis of the carbon/carbon compacts is performed for each variant. Higher heating rates give bloated compacts whereas low heating rates give bloating-free, finemicrostructure compacts. The compacts fabricated at higher pressure have displayed side oozing of molten pitch and discrete length carbon fibers.The microstructure of the compacts fabricated at low pressure shows a lack of densification.The compacts with low matrix precursor to reinforcement weight ratios have insufficientbonding agent to bind the reinforcement whereas the higher matrix precursor to reinforcement weight ratio results in a plaster-like structure. Based on the microstructure analysis, a heating rate of 0.2°C/min, pressure of 15 MPa, and a matrix precursor to rein-forcement ratio of 50:50 are found to be optimum w.r.t attaining bloating-free densificationand processing time.
        4,000원
        257.
        2014.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In industrial facilities sites, the conventional method determining the earthquake magnitude (M) using earthquake ground-motion records is generally not applicable due to the poor quality of data. Therefore, a new methodology is proposed for determining the earthquake magnitude in real-time based on the amplitude measures of the ground-motion acceleration mostly from S-wave packets with the higher signal-to-ratios, given the Vs30 of the site. The amplitude measures include the bracketed cumulative parameters and peak ground acceleration (As). The cumulative parameter is either CAV (Cumulative Absolute Velocity) with 100 SPS (sampling per second) or BSPGA (Bracketed Summation of the PGAs) with 1 SPS. The arithmetic equations to determine the earthquake magnitude are derived from the CAV(BSPGA)-As-M relations. For the application to broad ranges of earthquake magnitude and distance, the multiple relations of CAV(BSPGA)-As-M are derived based on worldwide earthquake records and successfully used to determine the earthquake magnitude with a standard deviation of ±0.6M.
        4,000원
        258.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The synthesis of carbon nanomaterials (CNMs) by a chemical vapor deposition method using three different plant oils as precursors is presented. Because there are four param-eters involved in the synthesis of CNM (i.e., the precursor, reaction temperature of the furnace, catalysts, and the carrier gas), each having three variables, it was decided to use the Taguchi optimization method with the ‘the larger the better’ concept. The best parameter regarding the yield of carbon varied for each type of precursor oil. It was a temperature of 900°C + Ni as a catalyst for neem oil; 700°C + Co for karanja oil and 500°C + Zn as a catalyst for castor oil. The morphology of the nanocarbon produced was also impacted by different parameters. Neem oil and castor oil produced carbon nanotube (CNT) at 900°C; at lower temperatures, sphere-like structures developed. In contrast, karanja oil produced CNTs at all the assessed temperatures. X-ray diffraction and Raman diffraction analyses confirmedthat the nanocarbon (both carbon nano beads and CNTs) produced were graphitic in nature.
        4,000원
        259.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to investigate the effect of enzyme and yeast extract supplement on growth performance, carcass characteristics and blood parameters in Hanwoo steers. A total of forty-eight 23-month-old Hanwoo steers, with average initial body weight of 545.25±12.60 kg, were assigned to four treatments with three replicates in a completely randomized design. Hanwoo steers housed in four heads group per pen. The treatments comprised of four groups of control (no feed additives), treatment 1 (xylanase, cellulase, and gluco-amylase; 0.1%/concentrate), treatment 2 (β-glucan and mannan-oligosaccharide; 0.1%/concentrate), and treatment 3 (treatment 1+2; 0.1%/concentrate). During the fourth and eighth month, average daily gain and feed conversion rates improved in treatment 1, but in the control this was lower than the other treatments (p<0.05). Real-time ultrasound was used for measuring the live carcass traits (longissimus muscle area, back fat thickness, and marbling score) and the better results were in the following order: treatment 1 > treatment 3 > treatment 2 > control, and extended to carcass grade. White blood cell indices were lower in treatments 2 and 3 and the IgG indices were relatively higher than in other treatments. As a result, levels of xylanase, cellulase, and gluco-amylase were increased from the fourth month to improve growth performance, live carcass traits. Durin
        4,300원
        260.
        2013.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to determine which spatiotemporal gait parameters obtained during hemiplegic walking could be a predictive factor for the Timed Up and Go test (TUG). Two hundreds nine subjects who had suffered a stroke were recruited for this study. They were participated in two assessments; the TUG test and gait analysis. The relationship between the TUG test and spatiotemporal parameters was analyzed using Pearson’s correlation coefficients. In addition, to predict the spatiotemporal gait parameters that correlated most with the TUG scores, we used multiple linear regression analyses (stepwise method). The results show that the normalized velocity was strongly correlated with the TUG performance (r=-.72, p<.001). Additionally, single support percentage (SSP), double support percentage (DSP), step time difference (STD), and step length difference (SLD) significantly were correlated with the TUG test. Normalized velocity, STD, DSP of affected side, and SSP of non-affected side explained 53%, 8%, 3%, 2%, of variance in the TUG test respectively. In conclusion, an increase in gait velocity and a decrease in STD would be effective indicators of improvement on the functional mobility in the stroke rehabilitation.
        4,000원