• 한국ITS학회 논문지
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• 제7권5호
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• pp.180-183
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• 2008

본 논문은 교통망에서 관측 링크 교통량, 미관측 링크의 이용자평형 정보를 이용하여 O-D행렬을 수학적으로 생성하는 모형을 제시하고 있다. 교통량이 관측되지 않은 링크로부터 이용자 평형 상태에서 추출 가능한 정보를 바탕으로 일련의 논리적 연산을 거쳐 실제교통량에 근접하는 서브알고리듬을 유추하여 O-D행렬 추정의 정확도와 연산의 일관성을 제고하였다. 이를 위해 이용자평형상태에서 새로운 정리(Theorem)와 보조정리(Lemma)를 유도하여 적용하였다. 모형의 시험은 3개의 초기 O-D 행렬과 3개의 미관측 링크 교통량 시나리오를 각각의 모형에 적용하여 그 결과를 비교하였다. 적용 결과 본 논문에서 제시된 모형은 기존의 이용자균형 접근방식의 모형emf에 비해 추정된 O-D값의 실제 값과의 차이(O-D Trip RMSE)가 현저히 감소되는 것을 확인하였다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.105-114
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• 2004

This study investigated the thermal behavior of the nuclear graphite waste generated from the decommissioning of the Korean nuclear research reactor, The first part study investigated the decomposition rate of the nuclear graphite waste up to $1000^{\circ}C$ under various oxygen partial pressures using a thermo-gravimetric analyzer (TGA). Tested graphite waste sample not easily destroyed in the oxygen-deficient condition. However, the gas-solid oxidation reaction was found to be very effective in the presence of oxygen. No significant amount of the product of incomplete combustion was formed even in the limited oxygen concentration of 4% $O_2$. The influence of temperature and oxygen partial pressure was evaluated by the theoretical model analysis of the thermo-gravimetric data. The activation energy and the reaction order of graphite oxidation were evaluated as 128 kJ/mole and 1.1, respectively. The second part of this study investigated the behavior of radioactive elements under graphite oxidation atmosphere using thermodynamic equilibrium model. $^{22}Na$, $^{134}Cs$ and $^{137}Cs$ were found be the semi-volatile elements. Since volatile uranium species can be formulated at high temperatures above $1050^{\circ}C$, the temperature of incinerator furnace should be minimized. Other corrosion/activation products, fission products and uranium were found to be the non-volatile species.

• Kyungpook Mathematical Journal
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• 제62권1호
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• pp.119-132
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• 2022

Virotherapy is an effective method for the treatment of cancer. The oncolytic virus specifically infects the lyse cancer cell without harming normal cells. There is a time delay between the time of interaction of the virus with the tumor cells and the time when the tumor cells become infectious and produce new virus particles. Several types of viruses are used in virotherapy and the delay varies with the type of virus. This delay can play an important role in the success of virotherapy. Our present study is to explore the impact of this delay in cancer virotherapy through a mathematical model based on delay differential equations. The partial success of virotherapy is guarenteed when one gets a stable non-trivial equilibrium with a low level of tumor cells. There exits Hopf-bifurcation by considering the delay as bifurcation parameter. We have estimated the length of delay which preserves the stability of the non-trivial equilibrium point. So when the delay is less than a threshold value, we can predict partial success of virotherapy for suitable sets of parameters. Here numerical simulations are also performed to support the analytical findings.

• International Journal of Concrete Structures and Materials
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• 제3권1호
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• pp.71-77
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• 2009

A theoretical model of multiple cracking failure mechanism is proposed herein for fiber reinforced high performance Cementitious composites. By introducing partial debonding energy dissipation on non-first cracking plane and fiber reinforcing parameter, the failure mechanism model of multiple cracking is established based on the equilibrium assumption of total energy dissipation on the first crack plane and non-first cracking plane. Based on the assumption of the first crack to be the final failure crack, energy dissipation terms including complete debonding energy, partial debonding energy, strain energy of steel fiber, frictional energy, and matrix fracture energy have been modified and simplified. By comparing multiple cracking number and energy dissipations with experiment results of the reference's data, it indicates that this model can describe the multiple cracking behavior of fiber reinforced high performance cementitious composites and the influence of the partial debonding term on energy dissipation is significant. The model proposed may lay a foundation for the predictions of the first cracking capacity and post cracking capacity of fiber reinforced high performance cementitious composites and also can be a reference for optimal mixture for construction cost.

• 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.

• 한국유기농업학회지
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• 제28권1호
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• pp.31-57
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• 2020

Korea-US FTA amendment became effective January 1, 2019 through several trade negotiations between the two countries. These amendments did not include changes in the agricultural sector. However, given the policy direction of the Trump administration, it is difficult to be certain that the existing Korea-US FTA on the agricultural sector will remain unchanged. This study examines the potential impact of changes in the US beef import tariff rates under the Korea-US FTA, which is progressively eliminated until 2026 using a dynamic partial equilibrium model. The modelling system is simulated with 100% decreases of tariff rates over 2020~2026 period and then compared to the baseline which is developed based on the current Korea-US FTA tariff rates. According to the scenario analyses results, 100% decreases of US beef tariff rate lowered Korean beef cattle production value up to 4.23%. Looking at this change in terms of absolute value rather than percentage, the total production value over 2020~2026 is expected to decrease by 815 billion won compared to Baseline. This reduction in production value in dynamic analysis is 67 billion won higher than the comparative static analysis.

• 한국유기농업학회지
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• 제30권2호
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• pp.151-170
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• 2022

The demand for commercial kimchi has increased continuously for the past 20 years due to the increase in eating out demand. Although Korean kimchi industry has expanded significantly, it is still small and a large portion of domestic demand is dependent on Chinese kimchi. Chinese kimchi imports has markedly increased over the last 20 years. However, kimchi imports from China in 2021 significantly reduced due to the recently released video showing a naked man making Kimchi. Korean government has decided to apply HACCP to all imported Kimchi from October 2021 in order to improve the safety of imported kimchi. This study analyzed the effect of changes in the amount of kimchi imports due to the introduction of HACCP on the kimchi industry by using a dynamic partial equilibrium model. According to the analysis result, if imports decreased by 20% compared to the Baseline, domestic kimchi production increased from 1.8% to a maximum of 4.8%, but kimchi consumption decreased from 3.1% to 5.2%. In particular, consumption away from home decreased from 3.3% to 5.7%. It is expected that the results of this study would be used as useful data in the decision-making process of market participants and policy makers related to the kimchi industry.

• 한국유기농업학회지
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• 제31권3호
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• pp.211-228
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• 2023

The Korea-US FTA was one of the most controversial FTAs Korea has ever signed and was expected to have a significant effect on the agriculture sector, especially the livestock industry. This study ex-post analyzed the impact of the Korea-US FTA on the Korean beef industry including the Jeonnam province using a dynamic partial equilibrium model. According to the scenario analysis results, if there was no Korea-US FTA, the beef imports would be reduced to as low as 0.24% to 4.19% compared to the Baseline applying existing Korea-US FTA beef tariff rates over the 2012 to 2022 periods. In addition, if there was no Korea-US FTA, the agricultural product value of Jeonnam and national Korean beef cattle would increase from 0.25% to 7.37% and 0.25% to 7.33%, respectively, compared to the Baseline. The results of the analysis are expected to be used as important information for policy establishment in preparation for CPTPP and supplementation of current FTA policies regarding Korean beef cattle not only for the central government but also Jeonnam province.

• 한국산학기술학회논문지
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• 제15권3호
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• pp.1471-1477
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• 2014

본 논문은 제주 월동무의 중장기 수급전망을 위해 구축된 수급전망모형의 개발 내용과 이 모형을 이용하여 2014-2018년 기간에 대한 수급 및 가격을 전망한 내용을 소개하고 있다. 제주 월동무 수급전망모형은 개별 품목에 대해 구축된 부분균형모형이며, 모형내 각 방정식들은 계량경제학 방법을 이용하여 추정되었다. 중장기 전망에 앞서 시행된 모형의 예측력은 RMSPE, MAPE, Theil의 불균등계수를 기준으로 검토되었다. 예측력 검토결과, RMSPE 기준으로 재배면적, 단수, 생산량, 소비량은 4% 이내의 매우 우수한 오차율을 보였고, 도매가격은 오차율 10% 이내의 비교적 양호한 예측력을 보였다. 중장기 수급 및 가격 전망결과, 제주 월동무 재배면적은 2013년 5,145ha, 2018년 6,650ha에 이를 것으로 전망된다. 월동무 생산량은 2013년 334,434톤으로 추정되고, 2018년 433,310톤으로 전망된다.

• 한국산학기술학회논문지
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• 제16권11호
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• pp.7781-7787
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• 2015

본 논문은 국내 양식 넙치 중장기 시장 규모 추정을 위해 구축된 수급전망모형을 개발한 내용과 이 모형을 이용하여 2015년-2017년 기간에 대해 시장 규모(수급 및 가격)를 예측한 내용을 소개하고 있다. 양식 넙치 수급전망모형은 단일품목 부분균형모형이며 동태 축차적 시뮬레이션 모형으로 개발되었고, 모형내 각 행태방정식은 계량경제학 방법을 이용하여 추정되었다. 중 장기 시장 규모 전망에 앞서 모형의 예측정확도는 RMSPE, MAPE, Theil의 불균등계수를 기준으로 검토되었다. 예측력 검토결과, 양식면적, 양성물량, 출하량, 도매가격은 모두 4% 이내의 양호한 오차율을 보였다. 국내 양식 넙치 시장 규모 전망결과, 생산량은 2015년 37,445톤, 2017년 42,561톤에 이를 것으로 전망되었고, 산지가격은 2015년 9,226원(1kg 기준), 2017년 10,191원될 것으로 전망되었다.