• 미래기술융합논문지
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• 제2권3호
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• pp.59-66
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• 2023

본 디지털 전환에서 가장 중요한 것은 SW 기술이다. 그러나 많은 기업이 SW 기술 및 인력 확보에 어려움을 겪고 있다. 특히 SW 인력 부족은 더욱 증가할 것이라 보고되고 있다. 정부는 SW 인력 수급정책을 해소하기 위해 인력양성 정책과 많은 지원사업을 수행하고 있지만, 이러한 정책이 효과적으로 수립되기 위해서는 소프트웨어 산업의 수요와 공급에 대한 정확한 예측이 필수적이다. 따라서 본 연구는 소프트웨어 산업의 수급 불균형을 해소하기 위해 동태적 구조 분석을 수행할 수 있는 시스템 다이내믹스 방법론을 활용하여 시뮬레이션을 개발하였다. 시스템 다이내믹스는 소프트웨어 산업의 인력 수급 불균형 현상에 대해 동태적인 시각에서 그 원인과 정책대안을 찾기에 적절하다. 세부적으로 미국의 노동통계국의(U.S. Bureau of Labor Statistics, BLS) 방법론을 사용하여 적용하여 소프트웨어 산업의 인력 수요 및 공급 예측 모델을 개발하였고, 시나리오 분석을 수행하여 정책적 시사점을 도출하였다.

• 전기학회논문지
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• 제62권11호
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• pp.1495-1504
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• 2013

Renewable energy integration and increased system complexities make system operator maintain supply and demand balance harder than before. To keep the grid frequency in a stable range, an appropriate spinning reserve margin should be procured with consideration of ever-changing system situation, such as demand, wind power output and generator failure. This paper propose a novel concept of dynamic reserve, which arrange different spinning reserve margin depending on time. To investigate the effectiveness of the proposed dynamic reserve, we developed a new short-term reliability criterion that estimates the probability of a spinning reserve shortage events, thus indicating grid frequency stability. Uncertainties of demand forecast error, wind generation forecast error and generator failure have been modeled in probabilistic terms, and the proposed spinning reserve has been applied to generation scheduling. This approach has been tested on the modified IEEE 118-bus system with a wind farm. The results show that the required spinning reserve margin changes depending on the system situation of demand, wind generation and generator failure. Moreover the proposed approach could be utilized even in case of system configuration change, such as wind generation extension.

• 한국통신학회논문지
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• 제30권1A호
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• pp.91-103
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• 2005

주문형 비디오 시스템의 설계에 있어 가장 중요하게 고려되고 있는 것은 사용되는 채널의 수를 일정하게 유지하면서 자입자의 대기시간을 줄이는 방법이다. 이러한 연구의 한 시도로 근래에 실시간 주문형 비디오와 유사주문형 비디오의 장점을 결합하는 결합형 주문형 비디오에 대한 연구가 활발히 이루어지고 있다. 결합형 주문형 비디오에 대한 연구는 결국 어떻게 유니캐스트 채널을 사용하는 사용자들을 그룹화하여 멀티캐스트 채널을 사용하도록 할 것인가에 대한 연구이다. 본 논문에서는 동적인 채널을 이용하여 시청자의 대기시간을 기존의 방식에 비해 효율적으로 줄일 수 있는 결합형 주문형 비디오를 제안하겠다. 모의실험 결과 제안된 방식은 10개의 비디오를 100의 채널을 이용하여 0.5 requests/second의 도착률로 서비스할 경우 Unified Video-on-Demand 비해 $551{\%}$의 성능향상을 보였다. 본 논문은 동적채널 할당을 이용하여 채널을 해제하고 다시 사용하는 과정, 성능 모델, 모의실험을 제시한다.

• 응용통계연구
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• 제29권1호
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• pp.193-203
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• 2016

본 논문은 ICT기반 시장에서의 수요관리시스템에서의 핵심 요소인 전력 수요 예측을 위하여, 전체 사용량을 기반으로 예측 하는 방식이 아닌, 시계열 기반 군집분석을 통한 군집별 예측량의 결합을 실시하였다. 시계열 군집 분석 방법으로서 Periodogram 기반의 정규화 군집분석, 예측 기반의 군집분석, DTW(Dynamic Time Warping)를 이용하여 군집화를 시도하였으며, 군집 별 수요예측 모형으로서 DSHW(Double Seasonal Holt-Winters) 모형, TBATS(Trigonometric, Box-Cox transform, ARMA errors, Trend and Seasonal components) 모형, FARIMA(Fractional ARIMA) 모형을 사용하여 예측을 실시하였다. 전체 사용량을 기반으로 예측 하는 방식이 아닌, 군집분석을 통한 군집별 예측량의 결합이 더 낮은 MAPE로 나타남에 따라 우수한 예측 방법으로 판단되었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.121-124
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• 2001

Dynamic Source Routing(DSR) 프로토콜은 이동 노드의 Multi-hop wireless ad hoc 망사용을 위해 특별히 디자인된 효율적인 라우팅 프로토콜이다. DSR은 일한 관리 없이 운용될 수 있도록 자기구조화 되어있으며 자기조직화 되어있다. "Router Discovery"와 "Router Maintenance"의 두 매카니즘으로 프로토콜은 구성되어 작동하며, 전적으로 on-demand로 작동한다. 본 논문에서는 multi-hop wireless ad hoc 망 상에서의 DSR 프로토콜 동작을 살펴보고, 시뮬레이션을 통한 DSR 프로토콜의 성능을 도시하여 DSR 알고리즘을 분석하고자 한다. DSR 알고리즘을 분석하고자 한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1546-1552
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• 2004

Railway schedule is periodically modified so that it could yield more profit by means of adjusting the schedule to demand. Most of related works are applicable under the given demand, but did not deal with dynamic relation between demand and schedule. To our knowledge, the methodology considering the relation is only the profitability evaluation model developed by SNCF. Our study suggests how to adjust the schedule to demand and therefore obtain more benefits using the profitability evaluation model.

• Structural Engineering and Mechanics
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• 제58권2호
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• pp.327-345
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• 2016

Many experimental and analytical studies have been conducted with beam-column subassemblages composed of a two-span beam to investigate the progressive collapse resistance of RC frames. Most study results reveal a strength-decreased transition phase in the nonlinear static load-deflection curve, which may induce dynamic snap-through response and increase the chord rotation demand for effective catenary action (ECA). In this study, the nonlinear static response is idealized as a piecewise linear curve and analytical pseudo-static response is derived for each linearized region to investigate the rotation demands for the ECA of the two-span RC beams. With analytical parameters determined from several published test results, numerical analysis results indicate that the rotation demand of 0.20 rad recommended in the design guidelines does not always guarantee the ECA. A higher rotation demand may be induced for the two-span beams designed with smaller span-to-depth ratios and it is better to use their peak arch resistance (PAR) as the collapse strength. A tensile reinforcement ratio not greater than 1.0% and a span-to-depth ratio not less than 7.0 are suggested for the two-span RC beams bridging the removed column if the ECA is expected for the collapse resistance. Also, complementary pseudo-static analysis is advised to verify the ECA under realistic dynamic column loss even though the static PAR is recovered in the nonlinear static response. A practical empirical formula is provided to estimate an approximate rotation demand for the ECA.

• 한국건축시공학회지
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• 제12권2호
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• pp.169-182
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• 2012

In the past, a strategic management of work demands has been increasingly challenged to design-build (DB) firms. Such a management is capable of providing sufficient profitable impact of a project on them. Total project profit is mainly related to actual resources, work completion time, amount of rework, and costs. The degree of recycling work packages in the DB project delivery system is used as a measure of the quality of the performed work. However, there are few models available to evaluate the impact of a demand management strategy on the DB firms and to predict its behavior. We propose a decision-making support model as an aid for assessing the amount of rework and for predicting project profit resulting in a convincible demand management strategy. This model is constructed by using a dynamic feedback approach that can analyze the problems arising in complex managerial systems. For the purpose of illustration, widely acceptable strategies were applied into the model to explore their impacts on the DB firms. The results indicate that the model is helpful for the managers in selecting the most appropriate demand management strategy for successfully achieving their objectives.

• 한국유기농업학회지
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• 제28권2호
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• pp.171-188
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• 2020

The Coronavirus disease (COVID-19), first identified in China in December 2019, has widely spread worldwide and is an ongoing pandemic. It is expected that the ripple effect of COVID-19 on the global economy including the agricultural sector will increase substantially if not properly controlled shortly. This study examines the potential impact of COVID-19 on the Korean beef cattle sector and farm labor demand for Korean beef cattle using a dynamic partial equilibrium model. The agricultural production value and farm labor demand for Korean beef cattle in the scenario assuming pessimistic GDP growth rate (-1.2% in 2020) with no direct supply shocks fell by up to 4.00% and 0.67%, respectively, compared to the baseline which represents the future without COVID-19 outbreak. On the other hand, the agricultural production value and farm labor demand for Korean beef cattle in the scenario assuming both pessimistic GDP growth rate and supply shocks (-12.7% beef imports and + 2.4% feed cost in 2020) increased by up to 12.08% and 1.99%, respectively, compared to the baseline.

• 한국컴퓨터정보학회논문지
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• 제23권5호
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• pp.9-14
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• 2018

For an efficient management of electricity market and power systems, accurate forecasts for electricity demand are essential. Since there are many factors, either known or unknown, determining the realized loads, it is difficult to forecast the demands with the past time series only. In this paper we perform a cluster analysis on electricity demand data collected from Jan. 2000 to Dec. 2017. Our purpose of clustering on electricity demand data is that each cluster is expected to consist of data whose latent variables are same or similar values. Then, if properly clustered, it is possible to develop an accurate forecasting model for each cluster separately. To validate the feasibility of this approach for building better forecasting models, we clustered data with t-SNE. To apply t-SNE to time series data effectively, we adopt the dynamic time warping as a similarity measure. From the result of experiments, we found that several clusters are well observed and each cluster can be interpreted as a mix of well-known factors such as trends, seasonality and holiday effects and other unknown factors. These findings can motivate the approaches which build forecasting models with respect to each cluster independently.