• Title/Summary/Keyword: small time-delay process

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A Tombstone Filtered LSM-Tree for Stable Performance of KVS (키밸류 저장소 성능 제어를 위한 삭제 키 분리 LSM-Tree)

  • Lee, Eunji
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.22 no.4
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    • pp.17-22
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    • 2022
  • With the spread of web services, data types are becoming more diversified. In addition to the form of storing data such as images, videos, and texts, the number and form of properties and metadata expressing the data are different for each data. In order to efficiently process such unstructured data, a key-value store is widely used for state-of-the-art applications. LSM-Tree (Log Structured Merge Tree) is the core data structure of various commercial key-value stores. LSM-Tree is optimized to provide high performance for small writes by recording all write and delete operations in a log manner. However, there is a problem in that the delay time and processing speed of user requests are lowered as batches of deletion operations for expired data are inserted into the LSM-Tree as special key-value data. This paper presents a Filtered LSM-Tree (FLSM-Tree) that solves the above problem by separating the deleted key from the main tree structure while maintaining all the advantages of the existing LSM-Tree. The proposed method is implemented in LevelDB, a commercial key-value store and it shows that the read performance is improved by up to 47% in performance evaluation.

Integrated Circuit of a Peak Detector for Flyback Converter using a 0.35 um CMOS Process (0.35 um CMOS 공정을 이용한 플라이백 컨버터용 피크검출기의 집적회로 설계)

  • Han, Ye-Ji;Song, Han-Jung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.42-48
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    • 2016
  • In this paper, a high-precision peak detector circuit that detects the output voltage information of a fly-back converter is proposed. The proposed design consists of basic analog elements with only one operational amplifier and three transistors. Because of its simple structure, the proposed circuit can minimize the delay time of the detection process, which has a strong impact on the precision of the regulation aspect of the fly-back converter. Furthermore, by using an amplifier and several transistors, the proposed detector can be fully integrated on-chip, instead of using discrete circuit elements, such as capacitors and diodes, as in conventional designs, which reduces the production cost of the fly-back converter module. In order to verify the performance of the proposed scheme, the peak detector was simulated and implemented by using a 0.35 m MagnaChip process. The gained results from the simulation with a sinusoidal stimulus signal show a very small detection error in the range of 0.3~3.1%, which is much lower than other reported detecting circuits. The measured results from the fabricated chip confirm the simulation results. As a result, the proposed peak detector is recommended for designs of high-performance fly-back converters in order to improve the poor regulation aspect seen in conventional designs.

Implementation of RSA modular exponentiator using Division Chain (나눗셈 체인을 이용한 RSA 모듈로 멱승기의 구현)

  • 김성두;정용진
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.12 no.2
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    • pp.21-34
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    • 2002
  • In this paper we propos a new hardware architecture of modular exponentiation using a division chain method which has been proposed in (2). Modular exponentiation using the division chain is performed by receding an exponent E as a mixed form of multiplication and addition with divisors d=2 or $d=2^I +1$ and respective remainders r. This calculates the modular exponentiation in about $1.4log_2$E multiplications on average which is much less iterations than $2log_2$E of conventional Binary Method. We designed a linear systolic array multiplier with pipelining and used a horizontal projection on its data dependence graph. So, for k-bit key, two k-bit data frames can be inputted simultaneously and two modular multipliers, each consisting of k/2+3 PE(Processing Element)s, can operate in parallel to accomplish 100% throughput. We propose a new encoding scheme to represent divisors and remainders of the division chain to keep regularity of the data path. When it is synthesized to ASIC using Samsung 0.5 um CMOS standard cell library, the critical path delay is 4.24ns, and resulting performance is estimated to be abort 140 Kbps for a 1024-bit data frame at 200Mhz clock In decryption process, the speed can be enhanced to 560kbps by using CRT(Chinese Remainder Theorem). Futhermore, to satisfy real time requirements we can choose small public exponent E, such as 3,17 or $2^{16} +1$, in encryption and verification process. in which case the performance can reach 7.3Mbps.

Data Synchronization Among Mobile Servers in Wireless Communication (무선통신 환경에서 이동 서버간의 데이터 동기화 기법)

  • Kim, Eun-Hee;Choi, Byung-Kab;Lee, Eung-Jae;Ryu, Keun-Ho
    • The KIPS Transactions:PartD
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    • v.13D no.7 s.110
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    • pp.901-908
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    • 2006
  • With the development of wireless communication techniques and mobile environment we are able to transmit data between mobile systems without restriction of time and space. Recently, researches on the data communication between mobile systems have focused on a small amount of sending out or receiving data and data synchronization at a fixed server and mobile clients in mobile environment. However, two more servers should be able to move mutual independently, information is shared with other systems, and data is synchronized in the special environment like a battlefield situation. Therefore, we propose a data synchronization method between systems moving mutual independently in mobile environment. The proposed method is an optimization solution to data propagation path between servers that considers limited bandwidth and process of data for disconnection communication. In addition, we propose a data reduction method that considers importance and sharing of information in order to reduce data transmission between huge servers. We verified the accuracy of data after accomplishing our data synchronization method by applying it in the real world environment. Additionally, we showed that our method could accomplish data synchronization normally within an allowance tolerance when we considered data propagating delay time by server extension.

Numerical Study of Evaporation and Ignition of in-line Array Liquid Droplets (액적 배열의 증발과 착화에 관한 수치해석적 연구)

  • 김충익;송기훈
    • Fire Science and Engineering
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    • v.13 no.1
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    • pp.37-47
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    • 1999
  • The spreading fire of very small floating particles after they are ignited is fast and t therefore dangerous. The research on this area has been limited to experiments and global simulations which treat them as dusts or gaseous fuel with certain concentration well m mixed with air. This research attempted micro-scale analysis of ignition of those particles modeling them as liquid droplets. For the beginning, the in-line array of fuel droplets is modeled by two-dimensional, unsteady conservation equations for mass, momentum, energy and species transport in the gas phase and an unsteady energy equation in the liquid phase. They are solved numerically in a generalized non-orthogonal coordinate. The single step chemical reaction with reaction rate controlled by Arrhenius’ law is assumed to a assess chemical reaction numerically. The calculated results show the variation of temperature and the concentration profile with time during evaporation and ignition process. Surrounding oxygen starts to mix with evaporating fuel vapor from the droplet. When the ignition condition is met, the exothermic reactions of the premixed gas initiate a and burn intensely. The maximum temperature position gradually approaches the droplet surface and maximum temperature increases rapidly following the ignition. The fuel and oxygen concentration distributions have minimum points near the peak temperature position. Therefore the moment of ignition seems to have a premixed-flame aspect. After this very short transient period minimum points are observed in the oxygen and fuel d distributions and the diffusion flame is established. The distance between droplets is an important parameter. Starting from far-away apart, when the distance between droplets decreases, the ignition-delay time decreases meaning faster ignition. When they are close and after the ignition, the maximum temperature moves away from the center line of the in-line array. It means that the oxygen at the center line is consumed rapidly and further supply is blocked by the flame. The study helped the understanding of the ignition of d droplet array and opened the possibility of further research.

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Implementation and Performance Evaluation of Transaction Protocol for Wireless Internet Services (무선 인터넷 서비스를 위한 트랜잭션 프로토콜의 구현과 성능평가)

  • Choi, Yoon-Suk;Lim, Kyung-Shik
    • Journal of KIISE:Information Networking
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    • v.29 no.4
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    • pp.447-458
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    • 2002
  • In this paper, we design and implement Wireless Transaction Protocol(WTP) and evaluate it for wireless transaction processing in mobile computing environments. The design and implementation of WTP are based on the coroutine model that might be suitable for light-weight portable devices. We test the compatibility between our product and the other products such as Nokia, Kannel and WinWAP For the evaluation of WTP, we use an Internet simulator that can arbitrary generate random wireless errors based on the Gilbert model. In our experiment, the performance of WTP is measured and compared to those of Transmission Control Protocol(TCP) and TCP for Transactions. The experiment shows that WTP outperforms the other two protocols for wireless transaction processing in terms of throughput and delay. Especially, WTP shows much higher performance In ease of high error rate and high probability of burst errors. This comes from the fact that WTP uses a small number of packets to process a transaction compared to the other two protocols and introduces a fixed time interval for retransmission instead of the exponential backoff algorithm. The experiment also shows that the WTP performance is optimized when the retransmission counter is set to 5 or 6 in case of high burst error rate.

Study on economic effects of outsourcing of food materials on the hotel kitchen - Focus on cooking Western food in the first class hotel - (식재료 아웃소싱이 경제적 주방에 미치는 영향에 관한 연구 - 특1급호텔 양식조리를 중심으로 -)

  • 성태종
    • Journal of Applied Tourism Food and Beverage Management and Research
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    • v.13 no.2
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    • pp.45-69
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    • 2002
  • This study is designed to examine feasibility and limitation of outsourcing in cooking Western food in a hotel, to interpret importance of outsourcing(eg. outside order, outside procurement, outside supply) in a broad sense in order to reinforce the core capacity in the cooking department, and to know whether the cooking human power is efficiently used and how much the chefs recognize outsourcing of food materials. As many companies conduct restructuring to cut down its size, the reduction of human power led the Western food cooking in the hotel to lower core capacities, lower quality, and lower efficiency. In addition, the sagging morale of chefs undermined creativity. To change from the traditional kitchen to an economic kitchen needs to look into importance of outsourcing, cognitive attitude of chefs, relation with outside suppliers. Here suggests performance of positive changes in the structure The study examined feasibility and limitation of outsourcing in the hotel kitchen as well as chefs' cognitive attitude toward outsourcing of food materials to reinforce core capabilities of the hotel kitchen. 1. Companies of outsourcing are selected according to variability of price conditions, flexibility of contract conditions, popularity of the outsourcing company, and reputation of the outsourcing company. 2. The importance of outsourcing in the Western food cooking is divided into 4 factors such as standard of selecting outsourcing companies, policies of cooking manu, quality of cooking, and quantity of cooking. 3. The most feasible section in outsourcing of food materials is a process of kneading flour for bread, which shows that many Western-food chefs expect to put higher possibility of outsourcing on the kneading. In other words, when it comes to confectionery and bakery, there are many outside expert processing companies supplying high quality products. In the order of outsourcing feasibility, sauce is followed by processed vegetable, garnish of main dish, and soup. The least feasible section in outsourcing of food materials is appetize. Appetize includes a concept of a improvised dish and needs speed. Due to its color, freshness, and sensibility of taste, the appetize plays a key role in the Western food cooking. 4. When outsourcing is taken in place, the highest risk is to lower the inner cooking skills. Therefore chefs in charge of the Western food sequently recognize both internal problems including storage of cooking skills, unstability of layoffs, and loss of cooperation between departments, and external problems including inferior goods, difficulty of differentiating manu, delay of delivery, and expiration date. It shows that most of the Western food chefs consider risks of the internal problems at first. 5. A effective outsourcing needs appropriate selection of outsourcing companies, maintenance of credibility, active communication, check and management of hygiene. However regardless of their position or career, chefs in charge of the Western food have the same cognitive attitude toward selecting successful outsourcing companies after the outsourcing system is enforced. The core of cooking, or a final stage in the full process of so-called artistic cooking, should be treated with insourcing. Reduction of several cooking processes resulted in shortened cooking time, increased efficiency, faster cooking, cutting the waiting-lines, and finally more room for customers. The outsourcing system can reduce or eliminate the following processes in cooking: buying various food materials, checking, storing, preparing, and processing. Especially in the Western food cooking department of a hotel, the outsourcing system should be enforced to make an economic kitchen and to efficiently manage it. Wow it's time to change from the traditional kitchen to an economic kitchen in the hotel cooking department. For that, the cooking department should become a small but strong organization by outsourcing except its core work.

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