• Journal of Ship and Ocean Technology
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• 제1권1호
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• pp.15-25
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• 1997

A series of towing tank tests were carried out for 18 full ship models of high block coefficients. The resistance coefficients and wake distribution at the propeller plane were measured and carefully examined. Regression analysis was employed to find out the relationships with the hull form parameters. Equations for wave resistance coefficient, form factor, and nominal wake are given. A harmonic analysis of measured wake was performed to look into the influence of the local stern shape on the magnitude of fluctuating wake components at three different radii. The amplitude of wake harmonics was also expressed by regression quations. It was found that the regression formulas were very useful in estimating resistance and circumferential wake characteristics of full ship models. It was also considered that the formulas presented in this paper could be utilized in the hull form improvement in a preliminary design.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.517-522
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• 2000

In the past few years, the nondestructive inspection technology has greatly developed due to the increased necessity to gain a complete understanding of the bridge behavior. Especially, the deformations of bridges contain a lot of informations about its health state. By measuring these deformations it is possible to analyze the loading and aging behavior of the structure. However, the current methods (such as LVDT, dial gage, optical displacement tranceducer, etc) are often of changeable application on site and have the limitations of installation. In this paper, the classical beam theory was reviewed and the deflections of structure are estimated using measured strain which is easy to acquire. The applicability of this algorithm is verified by a preliminary steel beam test and two types of concrete beam tests. Also fiber optic sensors as well as resistive strain gages were installed in the concrete beams to establish the applicability of fiber optic sensors in the field of civil engineering.

• 대한전자공학회논문지
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• 제9권1호
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• pp.1-6
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• 1972

통계적 상관법에 의하여 최대주기계열 신호를 시험신호로 2차 진동계의 임펄스 응답 추정에 관하여 이론적 및 실험적으로 검토 하였고, 그 측정 결과는 비교적 만족스러웠다. 이 방법은 실제 푸로쎄스에 적용시키는 경우 시험신호를 가하는 방법 및 지연신호의 검출 방법의 해결과 더부러 계통의 동정(동정)문제에 크게 기여될 것으로 전망한다.

• 한국기계가공학회지
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• 제16권1호
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• pp.77-82
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• 2017

A computer simulation method is introduced to understand the joining phenomena of PC and CFRP by estimating the temperature of the weld zone. Following the prior or preliminary research, the power range was set between 3 watts and 7 watts, and the scanning speed was set at 500 mm/min and 1,000 mm/min, respectively. Based on the computer simulation, the temperature near the joining boundary was not sufficient at the scanning speed of 1,000 mm/min, regardless of the selected powers. However, the temperature increases above the melting temperature of the selected polymers at the scanning speed of 500 mm/min. The simulation results were compared with actual weld samples to validate its actual use.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.622-624
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• 2014

A maglev train records a host of physical variables such as gaps, voltages and currents for suspension control and monitoring purposes. These data available from a maglev contains wealth of information that can be explored for various uses. One possible of such application is to use the gap data to estimate the shape of the rail, especially at the joints where rails are connected. The eddy current sensors that measure the gap between the rail and the car body produce large peaks around the joints. The suspension controller discards these peaks. Since the shape of the peaks is related to the joint, however, these peaks can be utilized to estimate the shape of the joints. In this paper, we present preliminary results on estimating the joint shape using the peak data. The results show that the approach is promising, albeit several technical difficulties to overcome.

• 천문학회보
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• 제41권1호
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• pp.67.2-67.2
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• 2016

SPT-CL J2106-5844 is known to be one of the most massive galaxy clusters ($M_{200}{\sim}1.27{\times}10^{15}M_{sun}$) ever found at z > 1. Given its redshift (z ~ 1.132), the mass of this cluster estimated by Sunyaev-Zel'dovich effect and X-ray observation is too large compared with the current ${\Lambda}CDM$ cosmology prediction. Mass estimation from these methods can be biased because they require assumptions on hydrostatic equilibrium, which are not guaranteed to hold at such high redshift (about 40% of the current age of the Universe). Thus, we need to verify the mass of this interesting cluster using gravitational lensing, which does not require such assumptions. In this work, we present our preliminary result of dark matter mass and its spatial mass distribution of SPT-CL J2106-5844 using weak-lensing analysis based on HST optical/NIR deep imaging data. We compare mass estimates from different sources and discuss cosmological implications.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.86-92
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• 2000

Recently, the Korea National Railways (KNR) is undertaking a program of electrification of the existing railway routes. In order to implement the ongoing plan, KNR authorized a preliminary engineering study of its electrical systems. This effort included a comprehensive analysis of new grounding networks. The new grounding system runs in parallel with the rails and is connected to all metal structures such as rails, overhead protection wires and substation grounding grids etc., creating an equipotential ground network. This paper presents a study on coupling levels that can disturb signaling and telecommunications in adoption of the new grounding network The simulation for the study is carried out using Matlab software, Several different scenarios are analyzed, including the load condition and a few fault conditions with different fault locations. The induced potentials on the communication cables are computed. The effect of the buried ground wires is also analyzed by comparing the results with and without the presence of the ground wires, The results presented in the paper can be used as a reference for estimating coupling levels in similar rail systems.

• Mass Spectrometry Letters
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• 제9권4호
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• pp.110-114
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• 2018

Since accumulation of chemicals in deciduous teeth can occur from the second trimester of fetal development to shedding, a deciduous tooth has been considered as an attractive biomatrix for estimating individual chemical exposures recently. Therefore, detection of organic chemicals from teeth has received an increasing attention in exposomics research. Most previous studies on organic chemical analysis of teeth not only focused on a few targeted chemicals but also ignored potential contaminants from an enamel surface or a dental pulp. Recently, our group started developing a multi-class organic analysis method for deciduous teeth and tried to find a proper incubation condition of tooth materials. Our results showed that incubation with methanolic HCl provided the best performance among tested.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.354-360
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• 2009

The demands for large-scale construction projects such as Mega-projects are largely increasing due to the rapid growth of increasing populations as well as the need to replace existing buildings and infrastructure. Increasing costs of materials, supplies, and labors require the first cost estimates at the preliminary planning stage to be as accurate as possible. This paper presents the results obtained from the survey on evaluating nine critical success factors that influence the accurate first cost estimates for large-scale projects from practical experiences. It then examines the current cost structures of construction companies for large-scale projects, followed by the causes for cost and schedule overrun. Twenty completed surveys were collected and the Analytic Hierarchy Process was applied to analyze the data. The results indicate that technology issues, the contract type, and social and environmental impacts are the significant leading factors for accurate first cost estimates of large-scale construction projects.

• 한국건설관리학회논문집
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• 제24권1호
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• pp.3-11
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• 2023

현재 국내에서는 건설공사 사후평가 제도에 따라 사업 준공 후 공사내용 및 그 효과를 조사하여 프로젝트의 성과를 평가하고 향후 계획된 유사 건설사업의 효율적인 수행을 위한 자료로 활용하고 있다. 그러나 건설사업의 성과를 보다 효과적으로 관리하기 위해서는 프로젝트 진행 과정에서 단계별 성과를 평가하여 그에 따른 유연한 관리전략을 수립할 수 있어야 한다. 따라서 건설사업의 효율적인 성과관리를 위해서는 건설사업 단계별 성과평가체계가 필요하다. 본 연구는 건설사업 초기단계의 성과를 평가할 수 있는 계획단계 벤치마킹을 위한 기초 모델을 제시하고자 한다. 이를 위하여 본 연구에서는 한국개발연구원에서 제공하고 있는 예비타당성 조사 보고서 중 완료된 도로공사 354건에 대해 데이터베이스를 구축하였다. 계획단계 성과를 평가할 성과지표로 시설용량을 기준으로 한 표준공사비와 표준공사기간 지표를 개발하여 도로사업의 계획단계의 성과를 분석할 수 있는 벤치마킹 모델을 제시하였다. 이를 통해 도로사업 계획단계의 표준공사비 및 표준공사기간을 산정하고, 도로사업의 특성별 차이를 분석하였다. 본 연구의 결과를 활용하여 계획단계의 성과와 설계 및 시공단계의 성과를 연계하여 분석한다면 건설사업 생애주기 동안의 성과관리가 가능할 것으로 기대된다.