• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.1201-1202
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• 2017

최근 IoT 관련 제품들과 IoT를 구현하기 위한 저전력 무선통신에 대한 관심이 높아지고 있다. 저전력 무선통신의 대표적인 예로는 BLE, Zigbee, Wifi, Z-Wave 등이 있다. 본 논문에서는 이러한 저전력 무선통신을 이용하는 디바이스들과 실시간으로 연동할 수 있는 저전력 무선통신 인터페이스 플랫폼을 설계하는 방법을 설명한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.313-315
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• 2004

본 논문은 IEEE 802.l1b 유무선 환경 에 서 TCP를 이용한 데이터 전송 시 에이젼트를 이용하여 패킷 손실의 원인을 분석, 무선 링크에서 발생한 패킷 손실에 대해서는 혼잡 윈도우 크기를 유지하고, 유선 링크에서 발생한 패킷 손실에 대해서는 지역 재전송을 수행하는 저전력 전송 기법을 제안하고 실제 구현한다. 제안하는 저전력 전송기법 은 전송 후 WNIC를 저 전력 모드로 전환 시킴으로써 WNIC 전력 소비를 최소화 한다. 실험 결과 높은 무선 링크 에러율(1~2%)에서 기존 TCP-Reno 보다 약 18% 에너지 감소 효과를 나타냈다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.224-225
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• 2019

본 논문은 에너지 절약을 위한 특정 상업용 에너지 저용량 에너지저장시스템 모델 개발 및 연구를 수행하였다. 저용량 에너지저장시스템은 피트니스센터의 스피닝 기계에의 적용을 목적으로 하고 있으며 제안하는 시스템은 BLDC모터, Rectifier, DC-DC Coverter, Controller, Battery 로 구성되어 있다. 본 논문에서는 각 구성요소간의 직병렬 연결을 통하여 저용량 에너지저장시스템의 효율적인 운영방안을 제시한다. 제안하는 저용량 에너지저장시스템은 시뮬레이션을 통하여 모델링 및 결과 분석을 진행하였다.

• Korea Petroleum Association Journal
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• s.306
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• pp.34-37
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• 2018

지난 수년간 저유가가 지속되면서 저유가 구도가 장기화내지 고착화되는 게 아니냐는 주장이 지배적이었다. 특히, 셰일혁명으로 불리는 미국의 셰일오일 증산이 무한정 계속되리라는 가정하에, 유가의 회복은 곧 미국 셰일오일의 증산으로 인한 과잉공급 상황을 가져오기 때문에 이제 저유가 구도는 장기적으로 고착화된다는 논리다. 더구나, 상대적으로 생산비가 낮은 사우디 등 산유국들은 미국 셰일 산업을 고사시키기 위하여 대응 증산을 할 것이기 때문에 유가회복은 요원하다는 인식이 지배적이었다. 그러나 사우디 및 미국 셰일오일의 증산 경쟁을 전제로 한 이러한 저유가 구도 장기화 주장은 더 이상 유효하지 않다는 것이 필자의 생각이다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.313-315
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• 2001

워크플로우 및 분산환경의 대두로 인하여 오늘날의 시스템은 다양하고 복잡한 정보의 관리에 대한 필요성이 요구되어지고 있다. 이에 기존의 데이터베이스를 이용한 일시적인 정보의 관리 및 데이터 공유뿐만 아니라 정보저장소에 의한 데이터의 관리 및 공유 또한 필요하게되었다. 이를 위하여 본 논문에서는 단일한 워크플로우뿐만 아니라 서로 다른 여러 워크플로우를 위하여 정보저장소를 관리 및 데이터를 공유할 수 있도록 정보저장소 관리 시스템을 설계한다.

• Journal of Nutrition and Health
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• v.49 no.2
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• pp.99-110
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• 2016

Purpose: The current study was conducted in order to identify health and nutritional status of Korean underweight women in their twenties by comparing with normal, overweight, and obese women. Methods: Data from the 2010~2012 Korea National Health and Nutrition Examination Survey were used in this study. Subjects were 897 women aged 20~29 years. Subjects were classified according to underweight, normal weight, overweight, and obese groups based on body mass index. Health status was assessed using data from the health questionnaire and examination. Nutritional status was assessed using data from 24-hour dietary recall and a food frequency questionnaire. Results: The underweight group had higher education and exercised less than the obese group. Means of blood chemistry and blood pressure of the underweight group did not differ from those of the normal weight group. Means of fasting glucose, insulin, lipid profiles, blood cell counts, and blood pressure in the underweight group were different from those of the overweight or obese group. Proportions of delivery, breast feeding, and irregular menstruation in the underweight group were lower compared with the other groups. Except retinol intake, means of nutrient intake did not differ among four groups. There were significant differences among four groups in the intakes of cereals and eggs and frequency of consumption of dairy products. Conclusion: The current findings showed that health and nutritional status of underweight women in their twenties did not differ from those of normal weight women. In particular, health status of underweight women in their twenties was better than that of obese women of the same ages. Further study on health and nutritional status of extremely underweight women is necessary.

• Polymer(Korea)
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• v.25 no.6
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• pp.833-839
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• 2001

The crystallization characteristics of metallocene linear low density polyethylene was investigated by small angle light scattering and comparison was made with Ziegler-Natta linear low density polyethylene. The special efforts were made to find out the effects of branching number, length of branching and co-monomer content of m-LLDPE on the crystallization behavior of m-LLDPE. It was found that m-LLDPE has longer induction time to start crystallization from the amorphous state than that of conventional LLDPE with similar branching number, but the rate of crystallization seems not change much in both LLDPEs. Lowering of branching number in m-LLDPE resulted in both increasing of rate of crystallization and reducing induction time to crystallize. In general, the maximum size of spherulites of m-LLDPE is bigger than that of conventional LLDPE.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1581-1587
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• 2014

Two-lalyered quiet asphalt pavements are well known for their noise reduction capabilities compared to the conventional ones. This study was conducted to analyze the economic effects on two-layered quiet asphalt pavement rather than on one-layered. Noise prediction was performed on the data surveyed from the two-layered quiet asphalt pavement. In addition, the economic analysis was executed considering cost benefits using the noise prediction result. The permeability test was also investigated to evaluate the clogging recovery of two-layered quiet asphalt pavement. Analysis results revealed that the construction cost of two-layered quiet asphalt pavements was cheaper than that of the conventional soundproof walls. The two-layered quiet asphalt pavement with simulated clogging conditions was satisfied the permeability requirements of the permeable asphalt pavements. The permeability test results showed that the permeable time was recorded as 6.77 seconds for one cycle of cleaning job with 400 mL of water.

• Polymer(Korea)
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• v.39 no.3
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• pp.388-393
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• 2015

Low molecular weight species were extracted from PC and SAN by a solvent extraction method in order to investigate the effect of low molecular weight species on interfacial tension and affinity between PC and SAN. From the analysis of molecular weight distribution by the GPC, it was confirmed that the low molecular weight species were effectively eliminated by the solvent extraction. Interfacial tension measurements and morphological observation were carried out with the PC and SAN of which the low molecular weight species were extracted. Interfacial tension was increased and the infinity was decreased for the extracted PC and SAN pair. This result implied that the low molecular weight species play a role as a compatibilizer between two polymers. Among two polymers, low molecular weight SAN contributes more in the compatibilization. Thus, it is favorable to use SAN containing a larger amount of low molecular weight species in fabrication of PC/ABS blend.

• The KIPS Transactions:PartD
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• v.15D no.1
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• pp.31-40
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• 2008

We generally use lower-dimensional transformations to convert high-dimensional sequences into low-dimensional points in similar sequence matching. These traditional transformations, however, show different characteristics in indexing performance by the type of time-series data. It means that the selection of lower-dimensional transformations makes a significant influence on the indexing performance in similar sequence matching. To solve this problem, in this paper we propose a hybrid approach that integrates multiple transformations and uses them in a single multidimensional index. We first propose a new notion of hybrid lower-dimensional transformation that exploits different lower-dimensional transformations for a sequence. We next define the hybrid distance to compute the distance between the transformed sequences. We then formally prove that the hybrid approach performs the similar sequence matching correctly. We also present the index building and the similar sequence matching algorithms that use the hybrid approach. Experimental results for various time-series data sets show that our hybrid approach outperforms the single transformation-based approach. These results indicate that the hybrid approach can be widely used for various time-series data with different characteristics.