• 품질경영학회지
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• 제51권2호
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• pp.171-184
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• 2023

Purpose: First, this paper suggests an alternative approach to find optimal portfolio (stocks, bonds and ESG stocks) under the maximizing utility of investors. Second, we include ESG stocks in our optimal portfolio, and compare improvement of welfares in the case with and without ESG stocks in portfolio. Methods: Our main method of analysis follows Brennan et al(2002), designed under the continuous time framework. We assume that the dynamics of stock price follow the Geometric Brownian Motion (GBM) while the short rate have the Vasicek model. For the utility function of investors, we use the Power Utility Function, which commonly used in financial studies. The optimal portfolio and welfares are derived in the partial equilibrium. The parameters are estimated by using Kalman filter and ordinary least square method. Results: During the overall analysis period, the portfolio including ESG, did not show clear welfare improvement. In 2017, it has slightly exceeded this benchmark 1, showing the possibility of improvement, but the ESG stocks we selected have not strongly shown statistically significant welfare improvement results. This paper showed that the factors affecting optimal asset allocation and welfare improvement were different each other. We also found that the proportion of optimal asset allocation was affected by factors such as asset return, volatility, and inverse correlation between stocks and bonds, similar to traditional financial theory. Conclusion: The portfolio with ESG investment did not show significant results in welfare improvement is due to that 1) the KRX ESG Leaders 150 selected in our study is an index based on ESG integrated scores, which are designed to affect stability rather than profitability. And 2) Korea has a short history of ESG investment. During the limited analysis period, the performance of stock-related assets was inferior to bond assets at the time of the interest rate drop.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권1호
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• pp.11-23
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• 2000

Photochemical air quality models are essential tools in predicting future air quality and assessing air pollution control strategies. To evaluate air quality using a photochemical air quality model, emission inventories are important inputs to these models. Since most emission inventories are provided at a county-level, these emission inventories need to be geographically allocated to the computational grid cells of the model prior to running the model. The conventional method for the spatial allocation of these emissions uses "spatial surrogate indicators", such as population for mobile source emissions and county area for biogenic source emissions. In order to examine the applicability of such approximations, more detailed spatial surrogate indicators were developed using Geographic Information System(GIS) tools to improve the spatial allocation of mobile and boigenic source emissions, The proposed spatial surrogate indicators appear to be more appropriate than conventional spatial surrogate indicators in allocating mobile and biogenic source emissions. However, they did not provide a substantial improvement in predicting ground-level ozone(O3) concentrations. As for the carbon monoxide(CO) concentration predictions, certain differences between the conventional and new spatial allocation methods were found, yet a detailed model performance evaluation was prevented due to a lack of sufficient observed data. The use of the developed spatial surrogate indicators led to higher O3 and CO concentration estimates in the biogenic source emission allocation than in the mobile source emission allocation.llocation.

• 한국물환경학회지
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• 제31권3호
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• pp.295-303
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• 2015

In Korea, Total Maximum Daily Loads(TMDLs) has been enforced to restore and manage water quality in the watersheds. However, some assesment of implementation plan of TMDLs showed that the achievement of the target water quality is not related to the proper allocation loads because difference of flow duration interval. In the United States, the discharge loads are determined by water quality modeling considering standard flow conditions according to purpose. Therefore, this study tried to develop the allocation method considering economical efficiency using water quality model. For this purpose, several allocation methods being used in the management of TMDLs is investigated and develope an allocation criteria considering regional equality and uniformity. Since WARMF(Watershed Analysis Risk Management Framework) model can simulate the time varying behavior of a system and the various water quality variables, it was selected for a decision support system in this study. This model showed fairly good performance by adequately simulating observed discharge and water quality in Miho watershed. Furthermore, the scenario simulation results showed that the effect of annual average water quality improvement to remove 1kg BOD is more than 25 times, even if point pollutants treatment facility is six times more expensive to operate than non-point pollutants treatment facility.

• 한국물환경학회지
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• 제26권1호
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• pp.168-176
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• 2010

This study proposes the improvement of the present Total Maximum Daily Load (TMDL) management system of MOE (Ministry of Environment). The margin of safety (MOS) is calculated by a method using standard error and a method using variability and uncertainty. The allocation of pollutant loads are calculated using three methods, equal load reduction method, equal percent removal method and method using equity standards. This study applied the improved TMDL management system to the Anyangcheon watershed. Since MOS varies from 12% to 44% due to the high variability of measured and simulated data, it must not be ignored in the TMDL. The method using equity standards is the most proper in this application since the others produced unrealistic allocations. Area, runoff, water use quantity, population and budget are considered for equity standards. This study shows that this allocation method can be also applicable for the administrative units as well as the sub-watersheds. Finally, Hydrologic Simulation Program-FORTRAN (HSPF) with the allocated pollutant load was used to confirm whether it satisfy the water quality standard or not. This study will be helpful to improve the MOS and allocation system TMDL in the future.

• 한국항공우주학회지
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• 제36권7호
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• pp.651-657
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• 2008

본 논문에서는 저사양의 반작용 휠을 이용하여 토크 가용성을 높이는 두 가지 기법이 제안 하였다. 첫 번째는 기존의 의사역행렬을 이용한 토크 제어 분배 법칙 대신 가중치가변 의사역행렬과 모멘텀을 최소화하는 제어 분배 법칙을 제안하여 반작용 휠의 토크, 모멘텀 제한 조건 내의 해를 찾도록 했다. 두 번째는 휠의 장착각을 변경하여 토크가 많이 필요한 축의 토크 가용성 자체를 증가시키는 방법을 제안하였다. 제안된 법칙들은 위성체의 자세 천이에 적용되었으며, 시뮬레이션을 통하여 성능 향상과 실제 위성의 적용 가능성을 기술했다.

• 한국통신학회논문지
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• 제35권7A호
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• pp.654-659
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• 2010

본 논문에서는 3GPP LTE 시스템에서 셀 주변부 및 하위 5%의 사용자 전송률을 높이기 위한 새로운 주파수 할당 기법을 제안한다. 단일 안테나 전송 방식(SISO: Single Input Single Output)에서 셀 주변부의 사용자 전송률을 늘리기 위하여 여러 가지 셀간 간섭 관리에 대한 연구가 활발히 진행되었으나, 간섭 관리 알고리즘 적용 방식이 실제 구현에 있어 상당히 복잡한 점이 있다. 제안하는 알고리즘은 모든 셀 영역에 동일한 주파수 할당 방식을 적용할 수 있어 운용의 복잡도를 낮추고, 셀 주변부의 사용자 전송량을 늘리도록 한다. 시스템 레벨 시뮬레이션(SLS: System Level Simulation)을 통하여 제안하는 알고리즘의 셀 주변부 및 하위 5% 사용자 전송률을 비교 분석한다.

• 한국멀티미디어학회논문지
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• 제10권12호
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• pp.1645-1654
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• 2007

In this paper, we study the problem of load balancing routing in clustered-based wireless mesh network in order to enhance the overall network throughput. We first address the problems of cluster allocation in wireless mesh network to achieve load-balancing state. Due to the complexity of the problem, we proposed a simplified algorithm using gradient load-balancing model. This method searches for a localized optimal solution of cluster allocation instead of solving the optimal solution for overall network. To support for load-balancing algorithm and reduce complexity of topology control, we also introduce limited broadcasting between two clusters. This mechanism maintain shortest path between two nodes in adjacent clusters while minimizing the topology broadcasting complexity. The simulation experiments demonstrate that our proposed model achieve performance improvement in terms of network throughput in comparison with other clustering methods.

• 한국과학교육학회지
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• 제17권4호
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• pp.511-524
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• 1997

The curriculum of science should be made of the education based on the acquirement instead of the knowledge. However, the present educational environment has many problems such as lack of laboratory and experimental facilities, and time limitations. One of the suggested methods to overcome the barriers in regular curriculum is the efficient operation of science club activities. Since the club activities are not restricted on time and space, teachers can apply various methods and programs. In this paper, we investigate the present operational status of science club activities in secondary school and some suggested improvement schemes of them It is shown that teacher training, reference development, time allocation, educational environment, facility completion and various program developments should be preceded, in order to activate science club activities.

• 한국통신학회논문지
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• 제28권9A호
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• pp.736-745
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• 2003

본 논문은 CDMA/TDD 시스템에서, 높은 전송률과 일정한 QoS를 갖는 실시간 클래스의 무선 자원 할당에 대한 방법론을 제시한다. 실시간 클래스와 비실시간 클래스를 제어하기 위하여, 예약 액세스 기법과 우선 순위 기법이 각각 제안된다. 또한 각 셀 링크간 간섭에 의한 성능 감소를 예방하기 위하여 슬롯 할당 기법을 제안한다. 제시된 방안들을 통하여 실시간 클래스의 연속성을 보장하고 비실시간 가입자를 최대로 수용할 수 있다. 다중 셀 환경과 멀티미디어 서비스 모델을 가정하여, 제안된 기법의 성능이 전송 지연, 채널 이용률 그리고 데이터 손실 등을 근거로 하여 평가된다. 시뮬레이션 결과는 상당한 성능 향상이 있음을 보인다.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.111-114
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• 2013

Underground construction requires long construction duration and a variety of equipment, and environmental management and improvement of its activities are considered necessary. For the purpose of the environmental improvement of underground construction activities, the appropriate development of technologies to reduce generated pollutants is mandatory. However, the analysis of the needs of technology development and the evaluation of development priorities should take precedence. In this research, the needs for the improvement of each construction activity are analyzed as a preliminary study for a proposed technology development plan to improve the environmental performance of underground construction. Firstly, environmental problem factors caused by underground construction activities are determined while underground construction types, methods, and activities are classified. A questionnaire survey to determine the needs for the improvement of each activity is then carried out. The survey indicated that the most urgent activity to be improved is that of cutting excavation, which causes environmental problems associated with flying dust. This study could be used as a basis for a technology development plan for the environmental improvement of underground construction activities. The result of this study, the priority of improvement needs, contributes to the effective allocation of a limited Research and Development (R&D) budget.