• 대한조선학회논문집
• /
• 제52권3호
• /
• pp.255-264
• /
• 2015

Wind load and flow field of a drillship with respect to various super structures were experimentally investigated in KARI 1m-wide wind tunnel with an atmospheric boundary layer simulation. Six-component external balance and Particle image velocimetry technique were used to measure wind load and velocity vectors in the flow-field around the model respectively. The experimental model was an imaginary shaped drillship with an approximated model which has 1/640 scale compared with recent typical drillships. The test Reynolds number based on the overall length was about 1.5×10⁶. It was found that dominant factors influencing on ship wind load are cabin shape and cabin height. Round cabin has smaller axial wind load and narrow boundary layer around the ship than rectangular one, but its yawing moment at certain angles becomes higher. Low cabin height also show positive effects on axial wind load too. Hull shape and forecastle shape show relatively small influences on wind loads except for slight changes around ±45° wind directions.

• 한국지반공학회논문집
• /
• 제26권7호
• /
• pp.135-145
• /
• 2010

최근까지 국내에서는 팽이기초에 관한 연구가 미흡하였고, 지반조건에 맞는 설계기준이 마련되어 있지 못하여 일본의 설계기준을 그대로 사용하고 있는 실정이다. 이로 인해 기존 팽이기초의 지지력식은 과소하게 예측되는 문제점이 있다. 따라서 본 연구에서는 실제크기의 1/5 스케일로 축소한 모형실험을 수행하였으며, 국내에서 이루어 진 100여개 현장의 재하실험 결과를 근거로 강도특성(N값), 지하수영향, 팽이기초의 파괴형상을 고려하여 보다 합리적으로 팽이기초의 지지력을 예측할 수 있는 식을 제안하였다.

• 응용통계연구
• /
• 제30권6호
• /
• pp.827-849
• /
• 2017

미국의 복지제도의 사회복지정책에서 종종 사용되는 자활(self-sufficiency; SS)은 사회복지학 분야에서 중요한 개념이며 많은 연구가 있어왔다. 이러한 연구들 중에는 심리적 자활(phycological SS; PSS)를 구성하는 자립 의지 척도(employment hope scale; EHS)와 인지된 고용 장벽 척도(perceived employment barrier scale, PEBS)가 미국의 저소득 구직자들의 경제적 자활(economic self-sufficiency; ESS)에 어떻게 영향을 미치는지에 대한 연구도 있다. 이러한 연구는 일반적으로 설문조사 자료를 이용하여 수행되며, 사회과학분야에서 설문조사 자료는 주로 구조방정식모형(structural equation model; SEM)으로 분석된다. 설문조사 자료에서는 일반적으로 측정변수의 개수가 많고 변수들 간에 상관관계가 있는 경우가 대부분이다. 이러한 경우 주성분 분석(principal component analysis; PCA)을 사용할 수 있다. 본 연구의 목적은 사회과학 분야에서 주로 다루는 설문조사 자료를 SEM과 PCA를 사용하여 분석하였을 경우 그 결과를 비교하는 것이다. 우리는 두 가지 분석 방법의 성능을 모의실험을 통하여 비교하였다. 우리는 또한 PSS와 ESS에 대한 실제 설문조사 자료를 이 두 가지 분석 방법으로 분석하고 그 결과를 비교하였다.

• 농촌계획
• /
• 제7권1호
• /
• pp.61-76
• /
• 2001

During the performance of large scale tidal land reclamation project along the coast line, the construction of large scale structures such as sea-dikes, closing estuaries will induce big changes of near-shore hydraulic behavior. In this paper, its is aimed to verify the change of tide and currents after the construction of sea-dike of the Saemangeum project along the coast line. Numerical scale model "TRISULA" which development by Delft Hydraulics in the Netherlands was used. "TRISULA" is adopting the finite difference numerical scheme, and mostly using for hydro-dynamic solution along the sea and estuaries. Model boundary is covering $100{\times}170$ Km and constructed with $133{\times}337$ grids. Outer side boundary is divided 48 sections, and input 37 tidal components are gained from another big scale numerical "Yellow Sea" model. Model calibrations & verifications were performed th field tide & current datas which were measured along sea-dike alignment during Aug. $1997{\sim}Apr$. 1999. And then, numerical simulation with the tide condition dated 17 Apr. 1999 was performed with & without sea-dike construction condition for the comparison. Evaluated boundary is 20 km out-side from sea-dike alignment. Four cross lanes were set up, each of lane contains 3 points, for the comparison of sea-dike construction effects. Results showing the tidal amplitude is reducing approximately 20 cm after the construction of sea-dike during spring tide condition, amplitude 6.9m. Currents after construction of sea-dikes along the alignment, the northern part shows 50%(inner), 90%(outer) and the southern part shows 10%(inner) 50%(outer) of the currents before construction.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2007년 가을학술발표회
• /
• pp.558-569
• /
• 2007

It is important to obtain real-time data from long-term monitoring of landfills and develop leachate leakage detection system for the integrated management of landfills. A novel real time monitoring system and early leakage detection system was suggested in this study. The suggested monitoring system is composed of two parts; (1) a set of moisture sensors which monitor the areas surrounding the landfill, and (2) a set of moisture and temperature sensors which monitor the landfill inside. For the assessment for landfills stabilization, real-time monitoring system was evaluated in dry and wet cell of pilot-site. In addition, the grid-net electrical conductivity measurement system was also suggested as early leakage detection system. In this study, the field applicability of suggested systems was evaluated through pilot-scale field tests. The results of pilot-scale field model tests indicate that the grid-net electrical conductivity measurement method can be applicable to the detection of landfill leachate at the initial stage of intrusion, and thus has a potential for monitoring leachate leakage at waste landfills.

• 한국철도학회논문집
• /
• 제9권1호
• /
• pp.50-56
• /
• 2006

This paper presents a mathematical model of the long-term track tamping scheduling problem in the Korean highspeed railway system. The presented model encompasses various operational field constraints, moreover improves a state-of-the-art model in extending the feasible space. We show the model is sized up to intractable scale, then propose another approximation model that is possible to handle with the present computer system and commercial optimization package, directly. The aggregated index, lot, is selected, considering the resolution of the planning horizon as well as scheduling purpose. Lastly, this paper presents two test results for the approximation model. The results expose the approximation model to quite promising in deploying it into an operational software program for the long-term track tamping scheduling problem.

• 지역사회간호학회지
• /
• 제12권3호
• /
• pp.647-660
• /
• 2001

Forming health care management model in small-scale enterprises was the purpose of this study. For the purpose, we tried to investigate the characteristics of small-scale enterprises and analyzed the pattern of their health care management. The results are as follow: 1. The strength of health managing agency and technical supporting program lies in team approach by specialized manpower. However, if the liaison between each part of the organization is not smooth, the overall management will be very difficult. 2. Small scale enterprises are characterized by their short life after the establishment, use of rental building, lack of welfare facilities, weakness in sanitary management and aggregation of factories of similar type of industry. Because of these characteristics, it is very difficult to solve problem basically, such as improvement of working environment. Therefore, it is important to focus on health education and community based approach. 3. Many workers in small-scale factories are in middle and old age. They have health problems mainly related to personal habits. Implementation of an appropriate health promotion program is needed. 4. The number of workplaces, which should be managed by health managing agent. is increasing rapidly. But the number of health managing agent is limited. In the aspect of the requirement of manpower and equipment, training personal agent is more urgent than founding institutional agent. 5. The uniform method of health management hampers the choice of employer and workers. The types of provision of health management should be diversified. 6. For an efficient management, a frequent visit of personal agent and the following referral to a specialist should be done. The specialists in charge of secondary management are from the field of occupational medicine, occupational hygiene, ergonomics, etc. 7. The health management of small-scale facilities should have six components. They are community-based approach, multi-disciplinary cooperative system, program based on the need of recipient, forming partnership of employer and worker, change of lifestyle, and evidence-based program.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
• /
• pp.34.1-34.1
• /
• 2009

After SNIa and WMAP observations during the last decade, the discovery of the accelerated expansion of the universe is a major challenge to particle physics and cosmology. There are currently three candidates for the dark energy which results in this accelerated expansion: $\cdot$ a non-zero cosmological constant, $\cdot$ a dynamical cosmological constant (quintessence scalar field), $\cdot$ modifications of Einstein's theory of gravity. The scalar field model like quintessence is a simple model with time-dependent w, which is generally larger than -w1. Because the different w lead to a different expansion history of the universe, the geometrical measurements of cosmic expansion through observations of SNIa, CMB and baryon acoustic oscillations (BAO) can give us tight constraints on w. One of the interesting ways to study the scalar field dark-energy models is to investigate the coupling between the dark energy and the other matter fields. In fact, a number of models which realize the interaction between dark energy and dark matter, or even visible matter, have been proposed so far. Observations of the effects of these interactions will offer an unique opportunity to detect a cosmological scalar field. In this talk, after briefly reviewing the main idea of the three possible candidates for dark energy and their cosmological phenomena, we discuss the interactinng dark-energy model, paying particular attention to the interacting mechanism between dark energy with a hot dark matter (neutrinos). In this so-called mass-varying neutrino (MVN) model, we calculate explicitly the cosmic microwave background (CMB) radiation and large-scale structure (LSS) within cosmological perturbation theory. The evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for the cosmic acceleration today.

• 한국농공학회논문집
• /
• 제59권6호
• /
• pp.89-100
• /
• 2017

The Agricultural Policy/Environmental eXtender (APEX) model was developed to extend EPIC's capabilities of simulating land management impacts for small-medium watershed and heterogeneous farms. APEX is a flexible and dynamic tool that is capable of simulating a wide array of management practices, cropping systems, and other land uses across a broad range of agricultural landscapes. APEX have its own agricultural environmental database including operation schedule, soil property, and weather data etc., by crops. However, agriculture environmental informations the APEX model has is all based on U.S. As this can cause malfunction or improper simulation while simulating highland field. In this study, database for APEX model to be utilized for South Korea established with 44,814 agriculture fields in Pyeongchang-gun, Korea from 2007 to 2016. And assessed domestic applicability by comparing T-P unit load criteria presented by National Institution of Environmental Research and result of APEX model. As a result of APEX model simulation, average T-P value for decade was 6.18. Average T-P of every year except 2011 was in range of 5.37~10.43 and this is being involved into criteria presented by National Institution of Environmental Research. It is analyzed that adjusting slope factor can make the model applicable for domestic agricultural environment.

• 한국안전학회지
• /
• 제12권2호
• /
• pp.70-79
• /
• 1997

This paper presents a study on the fuzzy linguistic variable based approach for safety assessment of human body in ELF electromagnetic field considering power system states. To cope with the demand in modern industry, the power system becomes larger in scale, higher in voltage. The advent of high voltage system has increased the relative importance of field effects. The analysis of ELF electromagnetic field based on Quasi-Static Method is introduced while the power system is included to model the expected and/or unexpected uncertainty caused by the load fluctuation and parameter changes. In order to analyze the power system, Monte Carlo simulation method and contingency analysis method are adopted in normal state and alert state, respectively. In the safety assessment of human body, the approach based on fuzzy linguistic variable is employed to overcome the shortcomings resulting from a crisp set concept. The suggested scheme is applied to a sample system(modified IEEE 14 bus system) to validate the usefulness.