• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.514-517
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• 2017

In solar photovoltaic systems, power generation is greatly affected by the weather conditions, so it is essential to predict solar energy for stable load operation. Therefore, data on weather conditions are needed as inputs to machine learning algorithms for solar energy prediction. In this paper, we use 15 kinds of weather data such as the precipitation accumulated during the 3 hours of the surface, upward and downward longwave radiation average, upward and downward shortwave radiation average, the temperature during the past 3 hours at 2 m above from the ground and temperature from the ground surface as input data to the algorithm. We analyzed the statistical characteristics and correlations of weather data and extracted the downward and upward shortwave radiation averages as a major elements of a feature vector with high correlation of 70% or more with solar energy.

• Korea Petroleum Association Journal
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• no.7 s.185
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• pp.77-79
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• 1996

95년중 우리나라는 1인당 국민소득이 처음으로 1만달러를 넘어 섰으며, 경제규모 (경상GNP)는 4,517억달러로 세계 11위, 교역규모는 2,603억달러로 세계13위(94년기준) 국가로 부상하였음. 경제구조면에서도 농림어업의 비중이 낮아지고 광공업 및 서비스업의 비중이 높아지는 등 산업구조가 고도화되었으며, 최종 소비지출의 비중이 낮아진 반면 설비 및 건설투자의 비중이 높아졌음. 또한 엥겔계수가 낮아지고 노동소득분배율이 높아지는 등 경제구조가 전반적으로 선진국형에 근접해가고 있는 것으로 나타났음. 이와 같은 경제발전에 따라 제조업 근로자의 주당 평균 근로시간, 인구 1만명당 의사수, 주택 보급률, 고등교육기관 학생수 및 연구개발투자액의 대GNP 비중 등 주요사회지표가 크게 호전된 것으로 나타났음. 특히 이중에서도 고등교육기관 학생수 및 연구개발투자액의 대GNP비중등은 우리나라의 높은 교육열등을 반영하여 주요국의 1만달러시기 수준보다 높은 것으로 나타났음.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.206-214
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• 2018

This paper proposes an impact point estimation algorithm of the rifle using microphone sensors. The proposed algorithm resolves the time synchronization problem by expanding the existing ToA (Time of Arrival) method to TDoA (Time Difference of Arrival) method and verifies the performance of the algorithm through the actual shooting experiments. By comparing analysis of the actual and the estimated impact points by the algorithm, it is confirmed that the proposed algorithm has excellent performance by estimating the impact point accurately within the tolerance range.

• Journal of Chest Surgery
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• v.37 no.9
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• pp.762-767
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• 2004

With the developement of non-invasive surgical techeniques, coronary artery bypass graft without cardiopulmonary bypass has become popular. We compared the preoperative risk factors and in-hospital outcomes of patients having off-pump CABG with these having on-pump CABG. Material and Method： From January 2001 to June 2003, 87 patients underwent CABG. Thirty-sin patients underwent on-pump CABG, fifty-one patients under-went off-pump CABG. Preoperative risk factors, extent of coronary disease, operative time, postoperative endotracheal intubation time, duration of ICU stay & hospital stay, the amount of bleeding and postoperative levels of cardiac enzymes were compared in both groups, Result: The were no differences in their sex ratios, ages, preoperative risk factors, preoperative Ml, Canadian classes, extent of coronary artery diseases and, echocardio-graphic ejection fraction between Off-pump CABG and On-pump CABG groups. Off-pump CABG group had significantly lower mean operative time (270$\pm$79.3 min vs 372$\pm$142.2 min, p＜0.001), mean ventilation time (17.1$\pm$13.4 hr vs 24.3$\pm$17.8 hr) and CK-MB level (8,9$\pm$18.7 IU/L vs 25.7$\pm$8.4 IU/L) than on-pump CABG groups, On-pump CABG group had more distal grafts (2.2$\pm$0.5 vs 1.7$\pm$0.71 than Off-pump CABG groups did. There were no differences in their postoperative complications and outcomes including amount of postoperative bleeding for 24 hrs, reoperation for bleeding control, mean in-hospital days, postoperative infection, renal failure and neurologic complications between Off-pump CABG and On-pump CABG groups. Conclusion: This study showed that patients who underwent Off-pump CABG had less operation time & intubation time and lower CK-MB level; however, they also have less distal graft. Even though CABG without CPB provided satisfactory results, more clinical experience & longer follow-up is required.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.11-21
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• 2006

Importance of and need for grid resource management have accelerated in accordance with increasing development of grid computing. However, it is very complex to distribute and utilize resources efficiently in geographically dispersed environments. This is due to the different access policies and constraints of grid resource owners. Users request resources according to their needs. Operators of a grid computing system need to be able to monitor the system states for reflecting these demands. So, a grid computing system needs a resource management policy that monitors states of resources and then allocates resources. This paper proposes a user demand-based grid trade management model that provides an efficient resource management by the trade allocation based on a users' demand and providers' supply strategy. To evaluate performance, this paper measures increasing rate of resource trades, average response time of trades, and processing time utilization. Firstly, the average increasing rates of trade are 585.7% and 322.6% higher than an auction model and a double auction model. Secondly, the average response time of the user demand-based grid trade management model is maintained between 3 and 5 simulation time. Finally, it is found that the processing time utilization is an average of 145.4% and 118.0% higher than an auction model and a double auction model. These empirical results demonstrate the usefulness of the user demand-based grid trade management model.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.83-93
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• 2014

It is a widespread concern that electrical interconnection based network-on-chip (NoC) will ultimately face the limitation in communication bandwidth, transmission latency and power consumption in the near future. With the development of silicon photonics technology, a hybrid optical network-on-chip (HONoC) which embraces both electrical- and optical interconnect, is emerging as a promising solution to overcome these problems. Today's leading edge systems-on-chips (SoCs) comprise heterogeneous many-cores for higher energy efficiency, therefore, extended study beyond regular topology based NoC is required. This paper proposes an energy and latency optimization topology design technique for HONoC taking into account the traffic characteristics of target applications. The proposed technique is implemented with genetic algorithm and simulation results show the reduction by 13.84% in power loss and 28.14% in average latency, respectively.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.653-655
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• 2014

스마트 디바이스 산업의 발전으로 소셜미디어 데이터의 양은 기하급수적으로 증가하고 있다. 이렇게 증가한 데이터와 함께 분석을 통해 발견할 수 있는 정보의 양도 다양해지면서 여러 산업분야에서 소셜미디어 데이터 분석을 위한 연구가 진행되고 있다. 소셜미디어는 종류가 다양하고 하루 평균 발생량이 너무 많기 때문에 분석시간이 오래 걸릴 뿐 아니라, 불필요한 불용어 및 방해요소 때문에 적절한 정제작업이 필요하다. 본 논문에서는 소셜미디어의 한 종류인 트위터 분석을 위해 여러 가지 기법으로 데이터를 정제한다. 정제과정은 분석에 용이한 형태로 데이터를 변형시킨 후 의미없는 데이터와 분석에 방해가 되는 불용어를 제거한다. 이 정제를 통해 데이터 정보의 질을 높이고 분석 시간을 단축시켜 빠르고 신뢰성 높은 분석결과를 도출할 수 있다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.257-266
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• 2015

There is no polynomial-time algorithm that can be obtain the optimal solution for economic load dispatch problem with non-convex fuel cost functions. Therefore, electrical field uses quadratic fuel cost function unavoidably. This paper proposes a valve-point optimization (VPO) algorithm for economic load dispatch problem with non-convex fuel cost functions. This algorithm sets the initial values to maximum powers $P_i{\leftarrow}P_i^{max}$ for each generator. It then reduces the generation power of generator i with an average power cost of $_{max}\bar{c}_i$ to a valve point power $P_{ik}$. The proposed algorithm has been found to perform better than the extant heuristic methods when applied to 13 and 40-generator benchmark data. This paper consequently proves that the optimal solution to economic load dispatch problem with non-convex fuel cost functions converges to the valve-point power of each generator.

• Informatization Policy
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• v.30 no.3
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• pp.69-91
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• 2023

The impact of technological advancements on employment is a matter of ongoing debate, with discussions on the effects of AI technology development on employment being particularly scarce. This study employs the natural language processing technique (SBERT) and patents to calculate an occupation-based AI exposure score and to analyze employment trends by group. It proposes a method for calculating the AI exposure score based on the similarity between Korean patent information and US job descriptions and linking SOC(U.S.) and KSCO(Korea). The analysis of domestic AI patent applications and regional employment data in the KOSIS Database since 2013 reveals a K-shaped polarization pattern in Korean employment trends among groups with above and below average levels of AI exposure.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.179-185
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• 2020

DRAM is a major component of the main memory system. As the operating system evolves and application complexity and capacity increases, the capacity and speed of DRAM are also increasing. DRAM should perform a refresh action of periodically reading and then re-storing stored values, and the accompanying performance and power/energy overhead embodies characteristics that worsen as capacity increases. This study proposes an energy efficiency improvement technique that efficiently stores the rows that need to be refreshed within 64ms and 128ms using the bloom filter for cells with the lowest retention time of electrons. The results of the experiment showed that the proposed technique resulted in an average 5.5% performance improvement, 76.4% reduction in average refresh energy, and 10.3% reduction in average EDP.