• 한국지진공학회논문집
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• 제7권2호
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• pp.93-102
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• 2003

지진 하중을 받는 전체 네트워크 시스템 및 네트워크 구성 절점에 대한 신뢰성 지수를 구할 수 있는 지진 재해 신뢰성 평가 방법을 전력 송전 네트워크 시스템을 대상으로 개발하였다. 전력 송전 시스템에 대하여 절점과 링크로 구성된 네트워크 모형을 개발하였으며, 절점인 변전소의 지진 취약도 곡선은 변전소 구성 기기의 개별 취약도 곡선으로부터 구하였다. 입력 지진 모형으로서 점 지진원 모형을 사용하였고, doubly truncated Gutenberg-Richter 관계식과 감쇠공식을 적용하였다. 몬테 카를로 시뮬레이션을 적용하여 전력 송전 네트워크 시스템의 신뢰성을 평가한 결과 한국의 전력망에 대한 지진 재해의 효과는 무시할 수 있는 수준은 아닌것으로 평가되었다.

• Smart Structures and Systems
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• 제9권4호
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• pp.335-353
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• 2012

This study suggests a simple two-step method for structural vibration-based health monitoring for beam-like structures which only utilizes mode shape curvature and few natural frequencies of the structures in order to detect and localize cracks. The method is firstly based on the application of wavelet transform to detect crack locations from mode shape curvature. Then particle swarm optimization is applied to evaluate crack depth. As the Rayleigh quotient is introduced to estimate natural frequencies of cracked beams, the relationship of natural frequencies and crack depths can be easily obtained with only a simple formula. The method is demonstrated and validated numerically, using the numerical examples (cantilever beam and simply supported shaft) in the literature, and experimentally for a cantilever beam. Our results show that mode shape curvature and few estimated natural frequencies can be used to detect crack locations and depths precisely even under a certain level of noise. The method can be extended for health monitoring of other more complicated structures.

• 전자공학회논문지B
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• 제33B권9호
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• pp.24-36
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• 1996

In this paper, we discuss the errors in selectivity estimation using the multilevel grid file (MLGF). We first demonstrate that the estimatio errors stem from the uniformity assumption that records are uniformly distributed in their belonging region represented by an entry in a level of an MLGF directory. Bsed on this demonstration, we then investigate five factors affecting the accuracy of estimation: (1) the data distribution in a region (2) the number of records stored in an MLFG (3) the page size, (4) the query region size, and (5) the level of an MLFG directory. Next we present the tendancy of estimation errors according to the change of values for each factor through experiments. The results show that the errors decrease when (1) the distribution of records in a region becomes closer to the uniform one, (2) the number of records in an MLFG increases, (3) the page size decreases, (4) the query region size increases, and (5) the level of an MLFG directory employed as data distribution information becomes lower. After the definition of the granule ratio, the core formula representing the basic relationship between the estimation errors and the above five factors, we finally examine the change of estimation errors according to the change of the values for the granule ratio through experiments. The results indicate that errors tend to be similar depending on the values for the granule ratio regardless of the various changes of the values for the five factors. factors affecting the accuracy of estimation:

• 대한전자공학회논문지TC
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• 제44권6호
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• pp.57-63
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• 2007

본 논문에서는 모노 펄스 추적용 배열안테나에서 주로 사용하는 선전원에 의한 차패턴 합성법을 새로이 제안한다. 제안한 방법에서는 잘 알려진 Bayliss의 차패턴 합성법과는 달리 Taylor의 선전원 합패턴 공식을 적절히 수정하여, 원하는 개별 sidelobe 레벨을 갖는 차패턴을 최적 합성한다. 즉, 차패턴과 해당 소스 분포함수와의 관계를 해석적으로 설정하고, 패턴이 갖는 null점을 최적으로 섭동시킴으로써 원하는 패턴과 해당 소스 분포함수를 동시에 도출한다. 더욱이 이 방법은 기존의 방법보다 빠른 sidelobe 감쇠율을 가지도록 한다. 수치적인 결과들로부터 제안한 합성과정의 타당성과 유용성을 보인다.

• 한국동물학회지
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• 제6권2호
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• pp.11-15
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• 1963

A total of 220 adult male mice (18-20g) of the S.M. strain were divided into ten experimental and control groups. The total-body X-ray irradiation doses used were 50 r, 100r, 200r, 400r, 600r, 800r, 1,000r, 1,200r, 1,400r, and1,600r. The respiratory arrest (mortality) caused by each irradiation doses were observed for 30 days. Relationships between irradiation doses and survival time and percentage of response were examined. From this experiment, a formula was obtained to express the relationship among three factors, which may be presented as follows : {{{{{{{{P= { 10} over { SQRT { 2 pi } } INT _{ - INF }^{ p'} e-{(p'-50)^2 } over {200 }dp···(a) p'=100 LEFT { t^0.3- LEFT ( { { 16.9965} over {D-60 } } RIGHT ) ^{ { 1} over {2.5 } } } / LEFT { LEFT ( { 26372.43} over {D-81.86 } RIGHT ) ^{ { 1} over {2.5 } } -( { { 16.9965} over {D-60 } } RIGHT ) ^{ { 1} over {2.5 } } ···(b) p= { (D-60) t^0.75-16.9965} over {0.2186 t^0.75 +263.55434 }····(c) }} {{{{P= { 10} over { SQRT { 2 pi } } INT _{ - INF }^{ p'} e-{(p'-50)^2 } over {200 }dp···(a) p'=100 LEFT { t^0.3- LEFT ( { { 16.9965} over {D-60 } } RIGHT ) ^{ { 1} over {2.5 } } } / LEFT { LEFT ( { 26372.43} over {D-81.86 } RIGHT ) ^{ { 1} over {2.5 } } -( { { 16.9965} over {D-60 } } RIGHT ) ^{ { 1} over {2.5 } } ···(b) p= { (D-60) t^0.75-16.9965} over {0.2186 t^0.75 +263.55434 }····(c)

• 한국지반공학회논문집
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• 제31권4호
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• pp.13-18
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• 2015

하중이 가해지면 수십 cm에서 수 m까지 침하가 발생하는 준설매립지반의 압축특성 파악은 매우 중요하다고 할 수 있으나, 고 합수비와 낮은 전단강도로 인해 불교란 시료채취가 불가능하고 압밀시험 또한 불가능한 실정이다. 이러한 문제를 해결하기 위해 본 논문에서는 N. Keith Tovey의 omega point와 점토의 물리적 특성변화에 대한 기본적인 가정을 이용하여 원지반과 준설매립점토 사이에는 $C_{c(d)}=F(e_d,C_c)$ 관계를 가진다는 것을 수학적으로 증명하였으며, 제안식의 신뢰성을 검증하기 위해 준설매립을 통해 지반이 조성된 국내 1개 현장에서 수행된 계측결과에 대한 분석결과, 매우 양호한 상관관계를 보이는 것으로 나타났다.

• 한국농공학회지
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• 제23권3호
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• pp.88-95
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• 1981

This study was carried out to investigate the relation between seepage losses and flow section area in earth canals. Totally 77 seepage measurement was gained by ponded method and the tested canals belong to the irrigation area of Farmland Improvement Association in each province, Korea. The results obtained from this study may be used as a reasonable criteria for the estimation of canal seepage losses in the design of irrigation systems. Obtained results are summarized as follows: 1. Average seepage rates in each Soils is 14cm/day in ML, 6. 3cm/day in CL and 24.9 cm/day in SM. 2. Water depth and water surface width in eath canals have little influenced on the seepage rate, while the seepage losses was increased in proportion as the water surface width lengthens. 3. A formula of S=C.An defining a relationship between seepage losses and flow section was derieved as follows. ML:S=O. 35 VA 1.20 (m$^3$/day/m) CL:S=O. 13 VA 0.84 SM:s=O.67VA-1.56 4. The average seepage loss rates per 1km of canal are as followings. Measured Time ML CL SM 0-4 hrs 2.2% 0.6% 4.5% 4-2 4hrs 1.0% 0.15% 2.0% In above table we may obtain the following results. The first row is suitable for the canal having short delivery time of irrigation, while the second row for the canal having long delivery time.

• Animal cells and systems
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• 제4권4호
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• pp.319-324
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• 2000

Species boundaries among the Alcyonacean soft coral, the genus Dendronephthya, are often obscured by inter- and intraspecific morphological variations. In the present study, we attempted to infer the genetic relationships of eight dendronephthians based on their molecular characters, the internal transcribed spacer (ITS) regions of ribosomal DNA, and then compared this result together with the random amplified polymorphic DNA (RAPD) data from our previous investigation. Dendronephthya. putteri and D. suensoni formed a divaricate form - VI grade specific clade, whereas D. castanea, D. gigantea, D. aurea and D. spinifera, formed a umbellate and glomerate form - IV and III grade specific clade. Therefore, we confirmed that the main characters the growth form and the anthocodial grade and formula, are important in identification of the species in dendronephthians despite some problems. Also, the relationships of the growth form are clarified as the glomerate form is much closer to the umbellate form than to the divaricate form based on two sets of independent molecular data. However, we cannot determine the molecular markers which limit the species boundaries among this genus with ITS sequences.

• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.372-380
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• 2012

The optical method Digital Speckle Correlation Measurement (DSCM) has been extensively applied due its capability to measure the entire displacement field over a body surface. A formula of displacement measurement errors by the gradient-based DSCM method was derived. The errors were found to explicitly relate to the image grayscale errors consisting of sub-pixel interpolation algorithm errors, image noise, and subset deformation mismatch at each point of the subset. A power-law dependence of the standard deviation of displacement measurement errors on the subset size was established when the subset deformation was rigid body translation and random image noise was dominant and it was confirmed by both the numerical and experimental results. In a gradient-based algorithm the basic assumption is rigid body translation of the interrogated subsets, however, this is in contradiction to the real circumstances where strains exist. Numerical and experimental results also indicated that, subset shape function mismatch was dominant when the order of the assumed subset shape function was lower than that of the actual subset deformation field and the power-law dependence clearly broke down. The power-law relationship further leads to a simple criterion for choosing a suitable subset size, image quality, sub-pixel algorithm, and subset shape function for DSCM.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권2_spc호
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• pp.55-69
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• 2020

Permeability-analyzing methods commonly involve small-scale drilling, such as pumping or slug test, but it is difficult to identify overall distribution of permeability of the entire target sites due to high cost and time requirement. Spectral induced polarization (SIP) method is known to be capable of providing distributions of both the porosity and the pore size, the two major parameters determining permeability of the porous medium. The relationship between SIP variables and permeability has been studied to identify the hydrological characteristics of target sites. Kozeny-Carman formula has been improved through many experiments to better predict fluid permeability with electrical properties. In this work, the permeability prediction techniques based on SIP data were presented in accordance with the hydrogeological and electrical characteristics of a porous medium. Following the summary of the techniques, various models and related laboratory experiments were analyzed and examined. In addition, the field applicability of the prediction model was evaluated by field case analysis.