• Title/Summary/Keyword: Apply and demand

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Transient Torsional Vibration Response due to Ice Impact Torque Excitation on Marine Diesel Engine Propulsion Shafting (선박용 디젤엔진 추진축에서 빙 충격 토크 기진에 의한 과도 비틀림 진동 응답)

  • Barro, Ronald D.;Eom, Ki Tak;Lee, Don Chool
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.5
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    • pp.321-328
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    • 2015
  • In recent years, there has been an increasing demand to apply the new IACS(International Association of Classification Societies) standards for ice and polar-classed ships. For ice-class vessel propulsion system, the ice impact torque design criterion is defined as a periodic harmonic function in relation to the number of the propeller blades. However, irregular or transient ice impact torque is assumed to occur likely in actual circumstances rather than these periodic loadings. In this paper, the reliability and torsional vibration characteristics of a comparatively large six-cylinder marine diesel engine for propulsion shafting system was examined and reviewed in accordance with current regulations. In this particular, the transient ice impact torque and excessive vibratory torque originating from diesel engine were interpreted and the resonant points identified through theoretical analysis. Several floating ice impacts were carried out to evaluate torque responses using the calculation method of classification rule requirement. The Newmark method was used for the transient response analysis of the whole system.

Novel User Offloading Scheme for Small Cell Enhancement in LTE-Advanced System (LTE-Advanced 시스템에서 소형셀 향상을 위한 새로운 사용자 오프로딩 기법)

  • Moon, Sangmi;Chu, Myeonghun;Lee, Jihye;Kwon, Soonho;Kim, Hanjong;Kim, Cheolsung;Hwang, Intae
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.19-24
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    • 2016
  • In Long Term Evolution-Advanced (LTE-A), small cell enhancement(SCE) has been developed as a cost-effective way of supporting exponentially increasing demand of wireless data services and satisfying the user quality of service(QoS). However, due to the dense and irregular distribution of a large number of small cells, the offloading scheme should be applied in the small cell network. In this paper, we propose an user offloading scheme for SCE in LTE-Advanced system. We divide the small cells into different clusters according to the reference signal received power(RSRP) from user equipment(UE). Within a cluster, We apply the user offloading scheme with the consideration of the number of users and interference conditions. Simulation results show that proposed scheme can improve the throughput, and spectral efficiency of small cell users. Eventually, proposed scheme can improve overall cell performance.

Clustering based Novel Interference Management Scheme in Dense Small Cell Network (밀집한 소형셀 네트워크에서 클러스터링 기반 새로운 간섭 관리 기법)

  • Moon, Sangmi;Chu, Myeonghun;Lee, Jihye;Kwon, Soonho;Kim, Hanjong;Kim, Daejin;Hwang, Intae
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.5
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    • pp.13-18
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    • 2016
  • In Long Term Evolution-Advanced (LTE-A), small cell enhancement(SCE) has been developed as a cost-effective way of supporting exponentially increasing demand of wireless data services and satisfying the user quality of service(QoS). However, there are many problems such as the transmission rate and transmission quality degradation due to the dense and irregular distribution of a large number of small cells. In this paper, we propose a clustering based interference management scheme in dense small cell network. We divide the small cells into different clusters according to the reference signal received power(RSRP) from user equipment(UE). Within a cluster, an almost blank subframe(ABS) is implemented to mitigate interference between the small cells. In addition, we apply the power control to reduce the interference between the clusters. Simulation results show that proposed scheme can improve Signal to Interference plus Noise Ratio(SINR), throughput, and spectral efficiency of small cell users. Eventually, proposed scheme can improve overall cell performance.

The Measures to Improve the Professionalism of Geography Teachers: Focusing on Teaching and Learning (지리교사 전문성 제고 방안: 교수.학습 측면을 중심으로)

  • Kim, Jin-Kuk;Nam, Sang-Joon
    • Journal of the Korean Geographical Society
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    • v.42 no.3 s.120
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    • pp.453-467
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    • 2007
  • This study has shown that geography teachers need the professionalism in a Teaching and learning aspect. Together with the transition of epistemology and the operation of the Subject Matter-based curriculum, etc the demand for professionalism of teachers is much higher than ever. But the less discussion about what the professionalism of geography teachers based on subject traits and its components are has been mentioned. Especially the previous studies related with geography teachers usually distinguished the contents from the methods in the geography teaching in a dichotomy and tried to apply to a class model in the theoretical aspects, so they $didn't^{\circ}{\varnothing}t$ present the enough measures to improve the professionalism of geography teachers in the synthetic aspects. In this study, after I found the components of professionalism required to geography teachers in a teaching and learning, I tried to present measures to improve the professionalism of geography leathers in the macroscopic aspects. The geography teacher should be a teacher to design a region as a process than a result, and a teacher as a reflective practitioner than a technical practitioner. The improvement of professionalism should be achieved through the process of cooperation with an educational reflection in the individual aspects.

Foreign Entry Strategies for Korean Fishery Firms (한국수산업의 해외진출전략에 관한 연구)

  • 김회천
    • The Journal of Fisheries Business Administration
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    • v.15 no.1
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    • pp.131-153
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    • 1984
  • Fishery resources are still abundant compared with other resources and the possibility of exploitation is probably great. The Korean fishery industry has grown remarkably since 1957, and Korea is ranked as one of the major fishery countries. Its of fishery products reached the 9th in the world and the value of exports was 5th in 1982. But recently a growth rate has slowed down, due to the enlargement of territorial seas by the declaration of the 200 mile, Exclusive Economic Zone, the tendency to develop fishery resources strate-gically in international bargaining, the change in function of the international organizations, the expansion of regulated waters, the illegal arrest of our fishing boats, the rapid rise in oil prices, and the fall in fish prices, the development of fishery resources as a symbol of nationalism, the fishing boats decreptitude, the rise of crew wages, regulations on fishing methods, fish species, fishing season, size of fish, and mesh size, fishing quotas and the demand of excessive fishing royalties. Besides the the obligation of coastal countries, employing crews of their host countries is also an example of the change in the international environment which causes the aggravation of foreign profit of fishing firms. To ameliorate the situation, our Korean fishery firms must prepare efficient plans and study systematically to internationalize themselves because such existing methods as conventional fishing entry and licence fishing entry are likely to be unable to cope with international environmental change. Thus, after the systematic analysis of the problem, some new combined alternatives might be proposed. These are some of the new schemes to support this plan showing the orientation of our national policy: 1. Most of the coastal states, to cope with rapid international environmental change and to survive in the new era of ocean order, have rationalized their higher governmental structure concerning the fishery industries. And the coastal countries which are the objectives of our expecting entry, demand excessive economic and technical aid, limit the number of fishing boats’entry and the use of our foreign fishing bases, and regulate the membership of the international fishery commissions. Especially, most of the coastal or island countries are recently independent states, which are poorer in national budget, depend largely on fishing royalties and licence entry fees as their main resources of national finance. 2. Alternatives to our entry to deep sea fishing, as internationalization strategies, are by direct foreign investment method. About 30 firms have already invested approximately US $ 8 million in 9 coastal countries. Areas of investment comprise the southern part of the Atlantic Ocean, the Moroccan sea and five other sea areas. Trawling, tuna purse seining and five other fields are covered by the investment. Joint-venture is the most prominent method of this direct investment. If we consider the number of entry firms, the host countries, the number of seas available and the size of investment, this method of cooperation is perhaps insufficient so far. Our fishery firms suffer from a weakness in international competitive ability, an insufficiency of information, of short funds, incompetency in the market, the unfriendliness of host coastal countries, the incapability of partners in joint-ventures and the political instability of the host countries. To enlarge our foreign fishing grounds, we are to actively adopt the direct investment entry method and to diversity our collaboraboration with partner countries. Consequently, besides proper fishing, we might utilize forward integration strategies, including the processing fied. a. The enterprise emigration method is likely to be successful in Argentina. It includes the development of Argentinian fishing grounds which are still not exploited in spite of abundant resources. Besides, Arentina could also be developed as a base for the exploitation of the krill resources and for further entries into collaboration with other Latin American countries. b. The co-business contract fishing method works in American territorial seas where American fishermen sell their fishery products to our factory ships at sea. This method contributes greatly to obtaining more fishing quotas and in innovation bottom fishing operation. Therefore we may apply this method to other countres to diffuse our foreign fishing entry. c. The new fishing ground development method was begun in 1957 by tuna long-line experimental fishing in the Indian Ocean. It has five fields, trawling, skipjack pole fishing and shrimp trawling, and so on. Recently, Korean fisheries were successful in the development of the Antarctic Ocean krill and tuna purse seining. 3. The acceleration of the internationalization of deep sea fishing; a. Intense information exchange activities and commission participation are likely to be continues as our contributions to the international fishery organizations. We should try to enter international fishery commissions in which we are not so far participating. And we have to reform adequately to meet the changes of the function of the international commissions. With our partner countries, we ought to conclude bilateral fishery agreements, thus enlarging our collaboration. b. Our government should offer economic and technical aids to host countries to facilitate our firms’fishery entry and activities. c. To accelerate technical innovation, our fishery firms must invest greater amount in technical innovation, at the same time be more discriminatory in importing exogeneous fishery technologies. As for fishing methods; expanded use of multi-purpose fishing boats and introduction of automation should be encuraged to prevent seasonal fluctuations in fishery outputs. d. The government should increases financial and tax aid to Korean firms in order to elevate already weak financial structure of Korean fishery firms. e. Finally, the government ought to revise foreign exchange regulations being applied to deep sea fishery firms. Furthermore, dutes levied on foreign purchaed equipments and supplies used by our deep sea fishing boats thould be reduced or exempted. when the fish caught by Korean partner of joint-venture firms is sold at the home port, pusan, import duty should be exempted.

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A Pre-Feasibility Test of Introducing Renewable Energy Hybrid Systems -Case Studies for 3 Off-Grid Islands- (도서지역 신·재생복합 전력시스템 보급 타당성 분석 -3개 도서지역 분석결과-)

  • Jang, HaNa;Kim, Suduk
    • Environmental and Resource Economics Review
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    • v.15 no.4
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    • pp.693-712
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    • 2006
  • A pre-feasibility test is done for renewable energy hybrid power systems at off~grid islands in which the current power supply is provided only by diesel generation. We apply Homer (Hybrid Optimization Model for Electric Renewables) which was developed by the National Renewable Energy Laboratory (NREL) for the analysis to identify the cost-minimizing combination of power generating facilities for the given load profiles. Chuja-Do, Geomun-Do and Youngsan-Do have been selected for our analysis considering the wind resources data of the Korea Institute of Energy Research (KIER). Information on wind speed, solar radiation and temperature is also used for the analysis. System component cost information from overseas market has been used due to the lack of domestic information. Site specific Load profile for electricity demand for those islands are reconstructed based on the partial survey results obtained form other sources. The LCOE of the least cost hybrid power systems for Chuja-Do, Geomun-Do and Youngsan-Do are $0.278/kWh, $0.234/kWh and $0.353/kWh, respectively Considering the fact that diesel generation is being subsidized at the price of $0.300/kWh by the government, first 2 cases are economically feasible for the introduction of renewable energy hybrid systems to those islands. But the third case of Youngsan-Do does not meet the criteria. The basic differences of these pre-feasibility test results are from the differences of the site specific renewable energy conditions, especially wind resources. In summary, promoting hybrid systems in the off-grid remote island should be based on the economic feasibility test results. Not all the off-grid islands are feasible for introducing this renewable energy hybrid system.

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Application of the SCE-UA to Derive Zone Boundaries of a Zone Based Operation Rule for a Dam (저수지 수위 구간별 운영률의 구간 경계 도출을 위한 집합체 혼합진화 알고리즘의 적용)

  • Kang, Shinuk;Kang, Taeuk;Lee, Sangho
    • Journal of Korea Water Resources Association
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    • v.47 no.10
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    • pp.921-934
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    • 2014
  • The purpose of the study is to derive a long term reservoir operation method that is easy to understand and apply to practical use for dam operators. The zone based operation rule is a simple method to make operation decisions by criteria corresponding to storage zones. The reservoir storage levels dividing a reservoir, however, must be determined by some methods. We developed a reservoir operation model based on the zone based operation rule and the shuffled complex evolution algorithm (SCE-UA) was used to determine storage levels for zone division. The model was applied to Angat Dam in the Philippines that has trouble in water supply due to imbalance between supply and demand. We derived a zone based operation rule for Angat Dam and applied it to the reservoir simulation of Angat Dam using the historical inflow. The simulation results showed water supply deficit and power generation were improved by 34.5% and 21.2%, respectively, when compared with the historical records. The current study results may be used to derive a long term reservoir operation rule.

Third Party's Legal Interest Protection from Commercialization of Drones -A focus on Decision of the German District Court- (카메라 장착 드론에 대한 지상 제3자의 법익 보호 - 독일의 하급심 판결을 중심으로 -)

  • Kim, Sung-Mi
    • The Korean Journal of Air & Space Law and Policy
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    • v.35 no.1
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    • pp.3-32
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    • 2020
  • With controlling Drones, although it was discussed in the previous study which showed a possibility. Which is personality and property rights of third parties could be violated while operating the drone with a video camera. But It's hard to find out precedents related to drones in Korea. In case of that someone try to control the drone which is equipped with a camera in a yard of neighborhood, the German District Court (Potsdam) considered an operator of drone has little bit of careless to do his duty and admit nonfeasance claim in the owner of the one's property for prevention to repetition of similar situation according to a nonfeasance claim for prevention to Section 1004 (1) sentence 2 of the German Civil Code(BGB). The drone which is equipped with a camera have possibilities to disrupt property and personal rights of the owner. Because a danger in repetition is getting larger regarding the violation of law. Moreover, there is a case that someone shot down the drone which is equipped with a camer. Because it has a risk to interrupt private life and cause some dangerous in our life. The German district court(Riesa) recently have considered that controlling the drone with a camera in private spaces is illegal as a violation of personal life. In addtion to, the action of property owner shot down drone is a legal according to § 228 of the German Civil Code(BGB) which is caleed "Necessity". Although it is difficult to apply to foreign cases directly to Korea, similar cases are likely to be occurred in Korea. The decision of the German District Court showed implications to Korea. As demand for the camera-equipped drone increases in Korea, it is time to discuss specific measures for drone violations.

Generalized kernel estimating equation for panel estimation of small area unemployment rates (소지역 실업률의 패널추정을 위한 일반화커널추정방정식)

  • Shim, Jooyong;Kim, Youngwon;Hwang, Changha
    • Journal of the Korean Data and Information Science Society
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    • v.24 no.6
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    • pp.1199-1210
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    • 2013
  • The high unemployment rate is one of the major problems in most countries nowadays. Hence, the demand for small area labor statistics has rapidly increased over the past few years. However, since sample surveys for producing official statistics are mainly designed for large areas, it is difficult to produce reliable statistics at the small area level due to small sample sizes. Most of existing studies about the small area estimation are related with the estimation of parameters based on cross-sectional data. By the way, since many official statistics are repeatedly collected at a regular interval of time, for instance, monthly, quarterly, or yearly, we need an alternative model which can handle this type of panel data. In this paper, we derive the generalized kernel estimating equation which can model time-dependency among response variables and handle repeated measurement or panel data. We compare the proposed estimating equation with the generalized linear model and the generalized estimating equation through simulation, and apply it to estimating the unemployment rates of 25 areas in Gyeongsangnam-do and Ulsan for 2005.

An Electric Load Forecasting Scheme with High Time Resolution Based on Artificial Neural Network (인공 신경망 기반의 고시간 해상도를 갖는 전력수요 예측기법)

  • Park, Jinwoong;Moon, Jihoon;Hwang, Eenjun
    • KIPS Transactions on Software and Data Engineering
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    • v.6 no.11
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    • pp.527-536
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    • 2017
  • With the recent development of smart grid industry, the necessity for efficient EMS(Energy Management System) has been increased. In particular, in order to reduce electric load and energy cost, sophisticated electric load forecasting and efficient smart grid operation strategy are required. In this paper, for more accurate electric load forecasting, we extend the data collected at demand time into high time resolution and construct an artificial neural network-based forecasting model appropriate for the high time resolution data. Furthermore, to improve the accuracy of electric load forecasting, time series data of sequence form are transformed into continuous data of two-dimensional space to solve that problem that machine learning methods cannot reflect the periodicity of time series data. In addition, to consider external factors such as temperature and humidity in accordance with the time resolution, we estimate their value at the time resolution using linear interpolation method. Finally, we apply the PCA(Principal Component Analysis) algorithm to the feature vector composed of external factors to remove data which have little correlation with the power data. Finally, we perform the evaluation of our model through 5-fold cross-validation. The results show that forecasting based on higher time resolution improve the accuracy and the best error rate of 3.71% was achieved at the 3-min resolution.