• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.224-224
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• 2011

5대 주요 수계의 소수력자원에 대하여 연구를 수행하였고, 하천의 유량지속특성을 예측할 수 있는 모델이 개발되었으며, 이를 이용하면 강우사상으로 야기되는 유입량의 변화에 대한 분석이 가능하다. 또한 소수력발전소의 성능을 예측할 수 있는 모델도 개발되었다. 안동댐에서 측정된 월유입량 자료를 분석하였으며,. 본 연구를 통해 개발된 모델을 이용하여 예측한 결과는 안동댐에서 오랜기간 동안 측정된 결과와 거의 일치되는 것으로 나타났다. 이는 개발된 모델들이 소수력발전입지의 이용가능한 잠재량과 기술적 잠재량을 예측하는데 효과적인 것으로 밝혀졌다. 본 모델들을 이용하여 수계별로 소수력발전입지에 대한 수문학적 성능을 분석하였다. 분석결과 소수력발전 입지의 수문학적 성능특성은 수계별로 차이가 있는 것으로 나타났다. 특히 북한강과 낙동강수계에 위치한 소수력발전입지의 비설계유량과 비출력량은 다른 수계들 보다 차이가 큰 것으로 나타났다. 그림 1은 수계별 비설계유량에 따른 비출력량의 변화를 나타낸다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.713-720
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• 2008

본 연구는 낙동강 하구 대심도 연약지반에 항타관입된 PHC 말뚝에 대하여 SPT 지지력 공식으로 부터 계산된 선단지지력 값과 PDA 시험에서 얻어진 선단지지력 측정값을 비교하였다. 또한, SPT N값이 50이 넘는 경우에 대하여는 N값과 롯드 관입깊이의 선형관계를 가정하여 30cm 관입깊이에 해당하는 N값을 적용한 경우와 CPT $q_c$와의 상관성을 이용하여 $q_c$값으로부터 N값을 산정한 경우의 2가지 분석을 수행하였다. 그 결과, 본 연구에서 적용한 SPT 지지력 공식 모두 측정된 선단지지력 값과 차이가 났으며, SPT 지지력 공식은 대심도 연약지반에 항타 근입된 말뚝에 대하여 실제적인 설계를 수행할 때 신뢰하기 어려운 것으로 나타났다. 또한, N>50인 경우에 대하여 N값과 롯드 관입깊이의 선형관계를 적용하는 것은 지지력을 매우 과대평가하는 것으로 나타났다.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.99-104
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• 2010

Purpose: Difference of refraction result from the method of autorefraction and iTrace were investigaged for the children of elementary school in Asan City. In iTrace method. exclusion of accommodation without cycloplegia was used. Methods: Manifest refractive stale of 42 eyes of 12~13 years old were measured using autorefractor and iTrace. Refractions of far (more than 5 m) and ncar (30 cm) vision were measured using iTrace. All data showed that the spherical equivalent were classified as being in the group 1 (-0.50D < ~ < +1.00D) and 2 (below -0.50D) according 10 refractive errors. Results: Mean spherical equivalent using autorefractor and iTrace (far and near vision) were -1.08D, -0.29D and -2.34D, respectively (p<0.01). Compared with the far vision using iTrace, autorefraction was measured the myopia with -0.50D ~ -1.00D in 52.4% of total eyes. Autorefraction also statistical significant were measured a more myopia than the far vision using iTrace in group I and 2. Conclusions: The difference of refractive errors between autorefraction and iTrace, objective refraction were measured with far vision of more than 5 m were -0.79D. Autoreftaction showed statistically decreased refraction errors than iTrace with far vision.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.329-338
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• 2019

Suction of unsaturated bentonite buffers is a very important input parameter for hydro-mechanical performance assessment and design of an engineered barrier system. This study analyzed suction measurement techniques and constitutive models of unsaturated porous media reported in the literature, and suggested suction measurement techniques and constitutive models suitable for bentonite buffer in an HLW repository. The literature review showed the suction of bentonite buffer to be much higher than that of soil, as measured by total suction including matric suction and osmotic suction. The measurement methods (RH-Cell, RH-Cell/Sensor) using a relative humidity sensor were suitable for suction measurement of the bentonite buffer; the RH-Cell /Sensor method was more preferred in consideration of the temperature change due to radioactive decay heat and measurement time. Various water retention models of bentonite buffers have been proposed through experiments, but the van Genuchten model is mainly used as a constitutive model of hydro-mechanical performance assessment of unsaturated buffers. The water characteristic curve of bentonite buffers showed different tendencies according to bentonite type, dry density, temperature, salinity, sample state and hysteresis. Selection of water retention models and determination of model input parameters should consider the effects of these controlling factors so as to improve overall reliability.

• 주택과사람들
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• s.194
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• pp.84-87
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• 2006

도시의 경쟁력은 부동산 가치와 도시의 수준을 나타내는 지표와 같다. 이와 같이 세계 각국의 도시 경쟁력을 비교 분석하기 위해 중국 청도에 8개국 학자들이 모여 '세계 도시 경쟁력 보고서(2005~2006)'를 공개 발표했다. 75개 지표를 통해 110개 도시의 경쟁력을 측정한 '세계 도시 경쟁력 보고서 2005~2006'를 살펴보자.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.494-499
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• 2004

The competitiveness of the domestic construction industry is faced with a serious crisis due to the decrease of domestic demands, and is below par with that of developed countries as well as of competing nations. There is a pressing need for a way to overcome this problem and restore competitiveness of the domestic construction industry. Therefore, this research, through real case studies, suggested a method of evaluating construction performance, which eliminates waste factors in each construction phase and maximizes cost saving effects.

• Journal of Korean Society for Geospatial Information Science
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• v.5 no.2 s.10
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• pp.153-167
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• 1997

The purpose of this study is to estimate the precision of GPS survey for the long baseline measurement. For this, we performed the simultaneous GPS observations at two points in Korea and nine points in Japan, and analyzed the precision of GPS survey by using broadcast ephemeris and precise ephemeris. As the results, in using precise emepheris and broadcast emepheris for the baseline less than 100km, each precisions are less than 0.1ppm. But the precision of precise emepheris is more improved than that of broadcast ephemeirs in the case of the baseline longer than 100km. That is, in comparing the results of VLBI and GPS survey, the precision is 0.13ppm for broadcast ephelneris and 0.04ppm for precise ephemeris. We expect that in the future this study will be used as the basic data for using broadcast ephemeris and precise ephemeris in GPS survey for the long baseline mearsurment.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.430-432
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• 2001

일반적으로 안과 의사들과 안경사 등을 포함하는 시각 관련 전문가들은 시력 피검자에 대한 굴절력 측정시 약 30% 이상의 오류율을 가진다고 한다. 이는 검사를 행하는 전문가의 비 숙련도에 기인한다기보다는 그만큼 시각 관련 측정이 유동적이고 민감해서 정확한 측정값을 얻어내는 것이 어렵다는 것을 말해주는 것이다. 만약 자동화된 시스템이 광학계로부터 나오는 영상을 이용하여 내부 처리를 거친 후 정확한 시각 측정치를 검사자에게 알려줄 수 있다면 잘못 측정되는 측정 횟수를 크게 줄일 수 있을 것이다. 본 연구는 형태학적 필터링(morphological filtering)과 그레이-레벨의 신호 강조(signal enhance) 기술들을 이용한 자동 시각 굴절력 측정 시스템을 개발하였다. 본 시스템에서는 광학계로부터 도출된 영상으로부터 첫째로 형태학적 필터링 처리를 행한다. 이 과정은 처리가 어려운 원 영상을 좀 더 다루기 쉬운 상태로 바꿔주는 역할을 하게 된다. 둘째는 일차 처리된 영상에 가해주는 그레이 수준 한계 기법을 통한 신호 강조 기법으로서 이는 영상의 그레이 값 분포가 다양함으로 인해서 발생되는 오차를 줄이기 위해서 사용된다. 그리하여 본 시스템은 정확한 측정값 도출이 어려운 시각 영상에 적용되어 효과적으로 오차를 줄임으로써 보다 효율적인 시각 측정을 가능하게 하였다.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.837-844
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• 1994

To investigate that the theoretical formulas for extrusion forces are applicable to the manufacturing plant, the maximum extrusion forces were calculated from Siebel's and Geleji's formulas and also measured using 550 ton extrusion press. Parameters such as flow stress, $K_f$, angle of dead metal zone, $\alpha$ were obtained experimentally in order to calculate the maximum extrusion forces by the the theoretical formulas, and it was showed that the results were reliable as the deformation efficient factor, $\eta _f$ was determined to be less than 0.5. The maximum extrusion forces calculated from Siebel's formula and Geleji's formula for the angle of dead metal zone, $\alpha = 50^{\circ}$ were approached to the experimental results. However, it was found that Siebel's formula is more useful to apply to the manufacturing plant.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.3
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• pp.279-284
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• 2012

Purpose: We measured the amplitude of accommodation using the push-up and push-away tests and near point of convergence (NPC) and investigated the accommodative insufficiency (AI) and convergence insufficiency (CI) in elementary school children of 12~13 years old. Methods: 88 students who aged 12~13 $12.63{\pm}0.51$ years old with more than 1.0 spectacle best corrected visual acuity were examined using push-up and push-away tests. The break and recovery points of NPC also were measured. Results: Mean amplitudes of accommodations using push-up and push-away tests were $11.52{\pm}2.50D$ and $10.06{\pm}1.97D$, respectively in right eye (P<0.001). Mean break and recovery points in NPC were $8.66{\pm}1.99cm$ and $10.98{\pm}2.06cm$. AI and CI showed 28.75% and 30.00% each. 48.75% was within normal range in both amplitudes of accommodations according to their age expected and convergence. Students having both AI and CI were 7.50%. Conclusions: A high correlation between the push-up test and push-away test was found in elementary school children (r=0.6025; P<0.05). Students having normal amplitude of accommodation by their age expected and normal convergence were 71.25% and 70.00%, respectively.