• 대한교통학회:학술대회논문집
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• 대한교통학회 1998년도 Proceedings The 4th International Transport Symposium
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• pp.160-167
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• 1998

Recent world-wide interest in activity-based travel behavior modeling has generated an entirely new perspective on how the profession views the travel demand process. This paper seeks to further promote the case of activity-based travel behavior models by providing some empirical evidence of relationship between travel time and activity duration decision for worker with transportation panel data. The travel time from home to work and from work to home, without activity involvement, is estimated by the Ordinary Least Squares (OLS) method. And, the travel time to and from the selected activity and the activity duration are modeled simultaneously by the Three Stage Least Squares (3SLS) method due to the endogenous relationship between travel time and activity duration. Two kinds of models, OLS and 3SLS, include selectivity bias corrections in a discrete/continuous framework, because of the inter-relationship between the choice of activity type/travel mode (discrete) and the travel time/activity duration (continuous). Estimation is undertaken using a sample of over 1300 household two-day trip diaries collected from the same travelers in the Seattle area in 1989. The behavioral consequences of these models provide interesting and provocative findings that should be of value to transportation policy formulation and analysis.

• 한국통신학회논문지
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• 제41권2호
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• pp.254-262
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• 2016

차량용 레이더 시스템에 대한 수요가 증가함에 따라서, 상호 간섭 문제는 차량 안전을 보장하기 위해 해결해야 할 결정적인 이슈가 되었다. Frequency modulated continuous wave(FMCW) 레이더의 상호 간섭은 잡음 전력 증가의 형태로 나타나며, 이는 간섭체로 인한 타겟 검출의 실패로 이어진다. 기존의 FMCW 레이더의 주파수 추정을 위하여 사용되는 fast Fourier transform (FFT) 기법은 차량용 레이더 간섭 환경에서는 취약하다. 이러한 단점을 극복하기 위하여, 본 연구에서는 간섭환경에서 사용하기 위한 고해상도 주파수 추정 기법을 제안한다. 제안된 알고리즘의 성능을 입증하기 위하여, 77GHz 전방 감시용FMCW 레이더 시스템을 도입하였다. 제안된 기법은 간섭환경에서도 정확하게 주파수를 추정할 수 있는 multiple signal classification, estimation of signal parameters via rotational invariance techniques과 같은 고해상도 알고리즘을 이용한다. 실험결과로부터 제안된 알고리즘이 기존의 FFT 알고리즘에 비해 신호 대 간섭비 측면에서 14 dB 이상의 마진을 가짐을 확인하였다.

• 대한간호학회지
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• 제16권3호
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• pp.108-122
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• 1986

Changing concepts of health care, are stimulating the demand for health care, thereby orienting society to health care rights to such an extent that they are deemed as fundamental ones inalienable to man. Concomitantly, qualitative as well as quantative improvement is being sought in the nursing service field. Today, efforts are being made in various areas, especially to qualitatively improve nursing services. A second issue concerns proper staffing. It is important to study staffing, in as much as it continues to be the most persistent and critical problem facing hospital nursing administrators today. It involves quantity, quality, and utilization of nursing personnel. A great deal of attention has been focused on this problem since mid 1930's when nursing services began to be felt as an important segment of hospital operation representing the largest single item of hospital budgets. Traditionally, the determination and allocation of nursing personnel resources has relied heavily on gloval approaches which make use of fixed staff-to-patient ratios. It has long been recognized that these ratios are insensitive to variations between institutions and among individual patients. Therefore, the aim of this thesis is to point to the urgent need for the development of methodology and criteria suited to the reality of Korea. The present research selected one place, the W Christian Hospital, and was conducted over a period 10 days from January, and nurses who were them on duty in their unit. The total num-her of patients surveyed was 1,426 and that of 354. The research represents many variables affecting the direct patient care time using the result from the direct observation method, then using a calculation method to estimate the relationship between the patients care time and selected variables in the hospital setting. The amount of direct patient care time varies with many factors, such 89 the patients age. diagnosis and time in hospital. Differences are also found from hospital, clinic to clinic, ward to ward, and even shift to shift. In this research, the calculation method of estimating the required member of nursing staff is obtained by dividing the time of productive patient care activity(with the time of patient care observed), by the sum of the productive time that each the staff can supply, i.e., 360 minutes, which is obtained by deducting the time for personal activities. The results indicate a substantial difference between the time of productive patient care observed directing and the time of the productive patient care estimated using calculating method. If we know accurately the time of the direct patient care on a shift, there required number of staff members calculated if the proper method can be determinded should be able the time of the direct patient care be estimated by the patient classification system, but this research has shown this system to be in accurate in Korea. There are differences in the recommended time of productive patient care and the required number of nursing staff depending upon which method is used. The calculated result is not very accurate, so more research is needed on the patient classification system.

• 한국수자원학회논문집
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• 제54권11호
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• pp.969-983
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• 2021

수문기상인자 중 하나인 증발산은 수자원 계획 및 관리 시 고려되며, 특히 물수지모형 등 수문모형의 입력자료로 활용된다. FAO56 PM 방법은 기상인자로부터 기준증발산량(reference evapotranspiration, ET₀)을 추정하며, 상대적으로 높은 정확성을 보여준다. 그러나 FAO56 PM 방법은 많은 기상인자가 필요하기 때문에 증발산 추정에 한계가 있다. 이러한 점에서 온도인자 기반의 Hargreaves 식의 매개변수를 Bayesian 모형을 통해 지역적으로 재추정하여 기준증발산량을 산정하였다. 통계 지표(CC, RMSE, IoA)를 활용하여 모형검증을 수행한 결과, 검증 기간에 대해 RMSE는 7.94 ~ 24.91 mm/month에서 6.77 ~ 12.94 mm/month로 기존 Hargreaves 식으로 추정된 증발산량에 비해 정확도가 크게 개선되었다. 본 연구에서는 산정된 기준증발산량을 활용해 증발 요구량(E₀) 기반의 가뭄지수 EDDI (evaporative demand drought index)를 제시하였다. 가뭄지수로서 적용성을 확인하기 위해 강수량 및 SPI와 함께 최근 2014 ~ 2015년, 2018년 가뭄사상을 평가하였다. 한강유역에 위치한 춘천, 홍천의 2018년 가뭄 발생 당시, 주단위 EDDI가 2 이상까지 증가하였으며, 이를 통해 EDDI가 강수부족보다는 폭염에 대한 반응정도가 큰 것을 확인할 수 있었다. 가뭄지수 EDDI는 SPI와 함께 가뭄 분석 및 평가에 대해 활용성이 높은 것으로 사료된다.

• Earthquakes and Structures
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• 제5권1호
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• pp.49-65
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• 2013

This article presents the statistical characteristics of elastic floor acceleration spectra that represent the peak response demand of non-structural components attached to a nonlinear supporting frame. For this purpose, a set of stiff and flexible general moment resisting frames with periods of 0.3-3.6 sec. are analyzed using forty-nine near-field strong ground motion records. Peak accelerations are derived for each single degree of freedom non-structural component, supported by the above mentioned frames, through a direct-integration time-history analysis. These accelerations are obtained by Floor Acceleration Response Spectrum (FARS) method. They are statistically analyzed in the next step to achieve a better understanding of their height-wise distributions. The factors that affect FARS values are found in the relevant state of the art. Here, they are summarized to evaluate the amplification and/or reduction of FARS values especially when the supporting structures undergo inelastic behavior. The properties of FARS values are studied in three regions: long-period, fundamental-period and short-period. Maximum elastic acceleration response of non-structural component, mounted on inelastic frames, depends on the following factors: inelasticity intensity and modal periods of supporting structure; natural period, damping ratio and location of non-structural component. The FARS values, corresponded to the modal periods of supporting structure, are strongly reduced beyond elastic domain. However, they could be amplified in the transferring period domain between the mentioned modal periods. In the next step, the amplification and/or reduction of FARS values, caused by inelastic behavior of supporting structure, are calculated. A parameter called the response acceleration reduction factor ($R_{acc}$), has been previously used for far-field earthquakes. The feasibility of extending this parameter for near-field motions is focused here, suggested repeatedly in the relevant sources. The nonlinearity of supporting structure is included in ($R_{acc}$) for better estimation of maximum non-structural component absolute acceleration demand, which is ordinarily neglected in the seismic design provisions.

• 보건행정학회지
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• 제16권1호
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• pp.95-116
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• 2006

According to rapid increase of the population of senior citizens, there has been growing concern of Long-Tenn Care(LTC) services recently. Long-Tenn Care services, however, haven't been established systematically in Korea and the supply of LTC services is not sufficient despite the increase in the current social demand. This study aims to estimate the 'Willingness to Pay(WTP)' for LTC insurance which the government plans to introduce by means of social insurance, using Contingent Valuation Method(CYM). In addition, this study analyzes the factors affecting WTP for LTC insurance. An interview survey was carried out to derive WTP for LTC from 450 people who lived in Seoul aged 20 and above during the period from 16th to 21st of June 2003. Double-Bounded Dichotomous Choice Method was applied among several CVMs available to estimate both use value and no-use value of goods. There was pilot survey carried out prior to the main survey. The results show that the average monthly. WTP for LTC provided in home and residential setting is 18,192Won and 19,293Won, respectively. In the case of home care, WTP goes higher depending on reliability of LTC insurance policy and need for LTC insurance, as well as marital status, education and average monthly income. On the contrary, WTP is conversely affected by higher age and higher bids. In the case of institutional care, the factors affecting WTP are similar to those of home care, except age. This study followed NOAA's suggestions generally and the value derived through survey could be reliable. However, there can be the least bias in the process of survey because the CVM should be used under the supposed circumstances. Despite those limitations, it can be concluded that the amount the citizens are willing to pay for LTC is high enough to meet the costs needed to provide LTC.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2001년도 학술대회지
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• pp.321-326
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• 2001

IMF 위기, WTO시장개방, 건설시장의 축소와 같은 외부 환경변화 속에서 건설산업은 국가 기반 산업으로서의 경쟁력을 상실해가고 있으며 많은 건설기업의 도산이 발생하였다. 이를 극복하기 위해 타분야와 마찬가지로 건설산업과 건설기업도 무형자산의 중요성에 주목하고 자체 경쟁력의 확보를 위해 지식경영을 도입하고 있으며 경영분석과 성과 측정의 관점에서 기업의 가치에 대한 평가가 필요하다. 기업의 가치를 형상화하는 것은 지극히 어려운 사항이며 가장 많이 사용되어지고 있는 재무자료에 의한 평가는 기업의 내재된 실질 가치를 나타내는데 한계를 가지고 있다. 현재 건설 기업에 대한 평가도 여러 가지 목적에 따라 이루어지고 있으나 재무제표를 중심으로 분석이 이루어져 정보가 가지는 한계성을 지니고 있으며 산업별 특성을 고려하지 않는 일률적인 평가가 이루어지고 있다. 본 연구는 국내 건설분야 상장기업64개 사의 3년 간(1998-2000) 자료를 바탕으로 간접무형자산 측정방법의 하나인 Market Capitalization Method(MCM)를 적용하여 국내 건설 기업의 무형자산 현황을 파악하고 향후 직접평가방법의 세부항목과의 상관 분석을 통한 새로운 형태의 기업 가치평가모델의 정립을 목적으로 하고 있다.

• 한국해양공학회지
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• 제32권3호
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• pp.184-191
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• 2018

Recently, as sea ice in the Arctic has been decreasing due to global warming, it has become easier to develop oil and gas resources buried in the Arctic region. As a result, Russia, the United States, and other Arctic coastal states are increasingly interested in the development of oil and gas resources, and the demand for offshore structures to support Arctic sea resources development is expected to significantly increase. Since offshore structures operating in Arctic regions need to secure safety against various drifting ice conditions, the concept of an ice-strengthened design is introduced here, with a priority on calculation of ice load. Although research on the estimation of ice load has been carried out all over the world, most ice-load studies have been limited to estimating the ice load of the icebreaker in a non-oblique state. Meanwhile, in the case of Arctic offshore structures, although it is also necessary to estimate the ice load according to oblique angles, the overall research on this topic is insufficient. In this paper, we suggest algorithms for calculating the ice load of managed ice (pack ice, 100% concentration) in an oblique state, and discuss validity. The effect of oblique angle according to estimated ice load with various oblique angles was also analyzed, along with the impact of ship speed and ice thickness on ice load.

• 대한교통학회지
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• 제28권1호
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• pp.63-74
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• 2010

최근 들어 학계와 연구원 등에서 기존의 교통혼잡비용 산정 방식과 내용에 대한 수정 요구가 증대하고 있다. 이에 본 연구에서는 교통혼잡비용에 대해 살펴보고, 교통혼잡비용의 개선방안을 도출하였다. 개선방안으로 교통혼잡비용에 사회적 외부비용을 추정에 포함하는 방안, 온실효과비용, 환경오염 비용 등을 교통혼잡비용의 추정에 합산하는 방안, 교통혼잡비용의 산정방법에 비 반복정체의 문제, 혼잡판단 기준속도의 문제, 혼잡시간대의 추정 문제, 통행속도 문제 등에 대한 대안을 도출하였다. 본 연구에서 제시한 교통혼잡비용 추정 개선 방안이 여러 가지 현실적용에 있어서의 어려움이 있는 한계를 가지고 있지만 지속가능한 발전이라는 시대의 흐름에 맞는 교통혼잡비용의 변화의 기초 자료로 제공하였다는 사실에 의의가 있다.

• 한국농공학회지
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• 제43권4호
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• pp.57-68
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• 2001

It is matter of common knowledge to give impetus to the water resources development to cope with increasing demand and supply for the water utilization project including agricultural living and industrial water owing to the economic and civilization development in recent years. Regional design rainfall is necessary or the design of the dam reservoir levee and drainage facilities for the development of various kinds of essential waters including agricultural water. For the estimation of the regional design rainfall classification of the climatologically an geographically homogeneous regions should be preceded preferentially This study was mainly conducted to derive the optimal regionalization of the precipitation data which can be classified by the climatologically and geographically homogeneous regions all over the regions except Cheju and Wulreung islands in Korea. A total of 65 rain gauges were used to regional analysis of precipitation. Annual maximum series for the consecutive durations of 1, 3, 6, 12, 24, 36, 48 and 72hr were used for various statistical analysis. Both K-means clustering and mean annual precipitation methods are used to identify homogeneous regions all over the regions. Nine and five homogeneous regions for the precipitation were classified by the K-means clustering and mean annual methods, respectively. Finally, Five homogeneous regions were established by the trial and error method with homogeneity test using statistics of $\chi$$^2$ distribution.