• Title/Summary/Keyword: Speed-Up

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Dietary factors affecting bone mineral density in Korean rural postmenopausal women (농촌지역 폐경후 여성의 골밀도 변화에 영향을 미치는 식이 요인 연구)

  • Choe, Jeong Sook;Ahn, Eun Mi;Kwon, Sung Ok;Park, Young Hee;Lee, Jinyoung
    • Journal of Nutrition and Health
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    • v.45 no.5
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    • pp.470-478
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    • 2012
  • This study was conducted to investigate dietary factors, bone status, and bone loss in postmenopausal women in rural areas. A total of 189 women participated in the follow-up study after two years. Radius, Tibia, and Phalanx SOS (Speed of Sound) was measured on two occasions 2 years apart by ultra-sonic-metry, and % body fat was measured by bioelectrical impedance analysis at the baseline and after 2years. Dietary intake data were collected 4 times at different season by 24-hour recall method, and then calculated as average. Bone density of radius decreased by 4.2% during the two year period. When the subjects were divided into three groups, by bone decline level during two years, the lowest bone loss group had higher potassium and vegetable intake than other groups. Age and calcium intakes showed significant correlation with bone decline rate at tibia. In multiple regressions, the baseline SOS, vitamin A, vegetables and eggs intakes were found to be significant factors for tibia bone decline. In conclusion, dietary factors, such as higher vegetable intake, seem to affect the changes in bone mineral density in more favorable way. Therefore, efforts are needed to enhance the access to nutritional care for rural elderly postmenopausal women.

Web Prefetching Scheme for Efficient Internet Bandwidth Usage (효율적인 인터넷 대역폭 사용을 위한 웹 프리페칭 기법)

  • Kim, Suk-Hyang;Hong, Won-Gi
    • Journal of KIISE:Information Networking
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    • v.27 no.3
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    • pp.301-314
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    • 2000
  • As the number of World Wide Web (Web) users grows, Web traffic continues to increase at an exponential rate. Currently, Web traffic is one of the major components of Internet traffic. Also, high bandwodth usage due to Web traffic is observed during peak periods while leaving bandwidth usage idle during off-peak periods. One of the solutions to reduce Web traffic and speed up Web access is through the use of Web caching. Unfortunately, Web caching has limitations for reducing network bandwidth usage during peak periods. In this paper, we focus our attention on the use of a prefetching algorithm for reducing bandwidth during peak periods by using off-peak period bandwidth. We propose a statistical, batch, proxy-side prefetching scheme that improves cache hit rate while only requiring a small amount of storage. Web objects that were accessed many times in previous 24 hours but would be expired in the next 24 hours, are selected and prefetched in our scheme. We present simulation results based on Web proxy and show that this prefetching algorithm can reduce peak time bandwidth using off-peak bandwidth.

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Development of an AIDA(Automatic Incident Detection Algorithm) for Uninterrupted Flow Based on the Concept of Short-term Displaced Flow (연속류도로 단기 적체 교통량 개념 기반 돌발상황 자동감지 알고리즘 개발)

  • Lee, Kyu-Soon;Shin, Chi-Hyun
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.15 no.2
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    • pp.13-23
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    • 2016
  • Many traffic centers are highly hesitant in employing existing Automatic Incident Detection Algorithms due to high false alarm rate, low detection rate, and enormous effort taken in maintaining algorithm parameters, together with complex algorithm structure and filtering/smoothing process. Concerns grow over the situation particularly in Freeway Incident Management Area This study proposes a new algorithm and introduces a novel concept, the Displaced Flow Index (DiFI) which is similar to a product of relative speed and relative occupancy for every execution period. The algorithm structure is very simple, also easy to understand with minimum parameters, and could use raw data without any additional pre-processing. To evaluate the performance of the DiFI algorithm, validation test on the algorithm has been conducted using detector data taken from Naebu Expressway in Seoul and following transferability tests with Gyeongbu Expressway detector data. Performance test has utilized many indices such as DR, FAR, MTTD (Mean Time To Detect), CR (Classification Rate), CI (Composite Index) and PI (Performance Index). It was found that the DR is up to 100%, the MTTD is a little over 1.0 minutes, and the FAR is as low as 2.99%. This newly designed algorithm seems promising and outperformed SAO and most popular AIDAs such as APID and DELOS, and showed the best performance in every category.

Design and Implementation of CW Radar-based Human Activity Recognition System (CW 레이다 기반 사람 행동 인식 시스템 설계 및 구현)

  • Nam, Jeonghee;Kang, Chaeyoung;Kook, Jeongyeon;Jung, Yunho
    • Journal of Advanced Navigation Technology
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    • v.25 no.5
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    • pp.426-432
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    • 2021
  • Continuous wave (CW) Doppler radar has the advantage of being able to solve the privacy problem unlike camera and obtains signals in a non-contact manner. Therefore, this paper proposes a human activity recognition (HAR) system using CW Doppler radar, and presents the hardware design and implementation results for acceleration. CW Doppler radar measures signals for continuous operation of human. In order to obtain a single motion spectrogram from continuous signals, an algorithm for counting the number of movements is proposed. In addition, in order to minimize the computational complexity and memory usage, binarized neural network (BNN) was used to classify human motions, and the accuracy of 94% was shown. To accelerate the complex operations of BNN, the FPGA-based BNN accelerator was designed and implemented. The proposed HAR system was implemented using 7,673 logics, 12,105 registers, 10,211 combinational ALUTs, and 18.7 Kb of block memory. As a result of performance evaluation, the operation speed was improved by 99.97% compared to the software implementation.

Design and Evaluation of a High-performance Key-value Storage for Industrial IoT Environments (산업용 IoT 환경을 위한 고성능 키-값 저장소의 설계 및 평가)

  • Han, Hyuck
    • The Journal of the Korea Contents Association
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    • v.21 no.7
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    • pp.127-133
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    • 2021
  • In industrial IoT environments, sensors generate data for their detection targets and deliver the data to IoT gateways. Therefore, managing large amounts of real-time sensor data is an essential feature for IoT gateways, and key-value storage engines are widely used to manage these sensor data. However, key-value storage engines used in IoT gateways do not take into account the characteristics of sensor data generated in industrial IoT environments, and this limits the performance of key-value storage engines. In this paper, we optimize the key-value storage engine by utilizing the features of sensor data in industrial IoT environments. The proposed optimization technique is to analyze the key, which is the input of a key-value storage engine, for further indexing. This reduces excessive write amplification and improves performance. We implement our optimization scheme in LevelDB and use the workload of the TPCx-IoT benchmark to evaluate our proposed scheme. From experimental results we show that our proposed technique achieves up to 21 times better than the existing scheme, and this shows that the proposed technique can perform high-speed data ingestion in industrial IoT environments.

Development of Operation Control and AC/DC Conversion Integrated Device for DC Power Application of Small Wind Power Generation System (소형 풍력발전시스템의 직류전원 적용을 위한 운전제어 및 AC/DC변환 통합장치 개발)

  • Hong, Kyungjin
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.19 no.3
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    • pp.179-184
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    • 2019
  • In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.

Wall Cuckoo: A Method for Reducing Memory Access Using Hash Function Categorization (월 쿠쿠: 해시 함수 분류를 이용한 메모리 접근 감소 방법)

  • Moon, Seong-kwang;Min, Dae-hong;Jang, Rhong-ho;Jung, Chang-hun;NYang, Dae-hun;Lee, Kyung-hee
    • KIPS Transactions on Computer and Communication Systems
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    • v.8 no.6
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    • pp.127-138
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    • 2019
  • The data response speed is a critical issue of cloud services because it directly related to the user experience. As such, the in-memory database is widely adopted in many cloud-based applications for achieving fast data response. However, the current implementation of the in-memory database is mostly based on the linked list-based hash table which cannot guarantee the constant data response time. Thus, cuckoo hashing was introduced as an alternative solution, however, there is a disadvantage that only half of the allocated memory can be used for storing data. Subsequently, bucketized cuckoo hashing (BCH) improved the performance of cuckoo hashing in terms of memory efficiency but still cannot overcome the limitation that the insert overhead. In this paper, we propose a data management solution called Wall Cuckoo which aims to improve not only the insert performance but also lookup performance of BCH. The key idea of Wall Cuckoo is that separates the data among a bucket according to the different hash function be used. By doing so, the searching range among the bucket is narrowed down, thereby the amount of slot accesses required for the data lookup can be reduced. At the same time, the insert performance will be improved because the insert is following up the operation of the lookup. According to analysis, the expected value of slot access required for our Wall Cuckoo is less than that of BCH. We conducted experiments to show that Wall Cuckoo outperforms the BCH and Sorting Cuckoo in terms of the amount of slot access in lookup and insert operations and in different load factor (i.e., 10%-95%).

Effects of Weather Factors on the Work Loss Days of the Elderly Workers (기상요소가 장년근로자의 근로손실일수에 미치는 영향)

  • Choi, Jaewook;Kim, Taewan;Lee, Chansik
    • Korean Journal of Construction Engineering and Management
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    • v.20 no.1
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    • pp.41-51
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    • 2019
  • With the aging of the population and the slowdown of the job market, elderly workers make up a large portion of the construction workforce. Also, due to the nature of the construction industry, where outdoor work is frequent, the weather has a more sensitive impact on elderly workers than on younger ones. The study aims to analyze the degree of weather risks exposed to elderly workers in the construction industry using the measure of work loss days. To that end, construction accidents that affected 28,514 elderly workers in seven cities from 2012 to 2016 (a total of 12,789 days) were analyzed to calculate work loss days per different weather factors. The results show that the elderly workers were seriously affected when the temperature was between $-12^{\circ}C$ and $-10^{\circ}C$, humidity between 55% and 60%, precipitation between 128mm and 181mm, and wind speed between 5.5m/s and 6.5m/s, with the highest work loss days. The combined effects between the weather factors were also analyzed to identify the conditiosn that leaded to high work loss days of elderly workers. This study contributes to effective safety management and pleasant working environment between weather factors and shedding light on the relationship between weather factors and work loss days of elderly workers.

The Impacts of Entrepreneurships on Learning Competence and Export Performance of INVs: the Moderating Effect of Environmental Factors (국제신벤처기업의 기업가정신, 학습역량, 수출성과의 관계에서 외부환경 요인의 조절 효과)

  • Cho, Yeon-Sung
    • International Area Studies Review
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    • v.16 no.3
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    • pp.3-25
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    • 2012
  • This study is to look at the relationship of entrepreneurship(innovativeness, risk-taking), the learning competence, environmental factors(the domestic market hostility, the speed of technological change) and export performance in international new ventures(INVs). In addition, the integrated model is constructed for the purpose of analysis of the moderating effects of environmental factors. Through the existing investigation, nine hypotheses are set up. PLS(Partial Least Square) analysis method is used to sample of 115 INVs. Analysis, the two elements of entrepreneurship influenced the positive(+) in the learning competence and export performance. And the relationship of learning competence and export performance is significant. In the moderating effects, only the domestic market hostility has a significant moderating effects between the learning competence and innovativeness. The results of this research shows that innovativeness influence the learning competence playing a positive role in the performance in the domestic market is higher. This point illustrates the practical implications of the importance of innovation in learning empowerment.

Analytic study on thermal management operating conditions of balance of 100kW fuel cell power plant for a fuel cell electric vehicle (100kW급 연료전지 열관리 시스템 실도로 운전조건 해석적 연구)

  • Lee, Ho-Seong;Lee, Moo-Yeon;Cho, Choong-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.2
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    • pp.1-6
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    • 2019
  • The objective of this study was to investigate performance characteristics of thermal management system(TMS) in a fuel cell electric vehicle with 100kW Fuel Cell(FC) system. In order to build up analytic modelling for TMS, each component was installed and tested under various operating conditions, such as water pump, radiator, 3-Way valve, COD heater, and FC stack etc. and as the results of them, correlations reflecting component's characteristics with flow rate, air velocity were developed. Developed analytic modelling was carried out under various operating conditions on the road. To verify modelling's accuracy, after prediction for optimum coolant flow rate was fulfilled under certain operating conditions, such as FC system, water pump speed, opening of 3-way valve, and pipe resistance, analytic and experimental values were compared and good agreement was shown. In order to predict cold-start operating performance for analytic modelling, coolant temperature variation was analyzed with $-20^{\circ}C$ ambient temperature and duration was predicted to rise in optimum temperature for FC. Because there is appropriate temperature difference between inlet and outlet of FC stack to operate FC system properly, related analysis was performed with respect to power consumption for TMS and heat rejection rate and performance map was depicted along with FC operating conditions.