• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.484-493
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• 2004

A new lightwave locking technique which can be used in tuning the wavelength of a local laser diode to the reference wavelength is presented in this paper. The optical frequency from the reference laser source and the optical frequency from the local slave VCO laser are heterodyned on a optical receiver, resulting in the 1.5GHz RF signal corresponding to the difference frequency between two input optical signals. The difference frequency is locked to the reference 1.5GHz oscillator source in off-set frequency locking loop. Using the commercialized microwave components, frequency difference detector can be easily established to lock the lightwave. The optical frequency of 1.55um laser diode which keeps the frequency off-set of 1.5GHz is locked to the input reference optical signal with the locking range of 320MHz.

• Journal of KIISE:Databases
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• v.32 no.6
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• pp.628-640
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• 2005

The XML is well accepted in several different Web application areas. As soon as many users and applications work concurrently on the same collection of XML documents, isolating accesses and modifications of different transactions becomes an important issue. When an XML document correctly corresponds to the rules laid out in a DTD or XML schema, it is also said to be valid. The valid XML document's validity should be guaranteed after the document is updated. The validation method mentioned above, however, results in lower degree of concurrency. For getting higher degree of concurrency and minimizing the range of the XML document validity, a new validation method based on a specific locking method is required. In this paper we propose the sequence group validation method for minimizing the range of the XML document validity. We also propose the boundary locking method for isolating accesses and modifications of different transactions while supporting the valid XML document's validity. Finally, the results of some experiments show the validation and locking methods increase the degree of transaction concurrency.

• Journal of KIISE:Software and Applications
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• v.26 no.2
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• pp.223-233
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• 1999

데이터베이스 공유 시스템(Database Sharing System : DSS) 은 고성능의 트랜잭션 처리를 위해 제안된 구조이다. DSS에서 고속의 통신망으로 연결된 노드들은 별도의 메모리와 운영체제, 그리고 DBMS를 가지며, 데이터베이스르 저장하고 있는 디스크는 모든 노드에 의해 공유된다. 빈번한 디스크 액세스를 피하기 위해 각 노드는 자신의 메모리 버퍼에 최근에 액세스한 페이지들을 캐싱한다. 본 논문에서는 레코드와 같은 미세 단위의 로킹을 지원하는 DSS에서 데이터베이스를 정확한 상태로 복구할 수 있는 회복 기법인 DRCP(Database Recovery using Cached Pages)를 제안한다. DRCP는 정상적으로 동작하고 있는 다른 노드에 캐싱된 페이지의 내용을 참조하여 회복 작업을 수행함으로써 디스크 액세스 수와 회복 과정에서 필요한 로그 스캔의 범위를 줄일 수 있고 , 그 결과 데이터베이스를 빨라 복구할 수 있다는 장점을 갖는다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.8
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• pp.488-490
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• 2014

This paper deals with distributed time and frequency synchronization algorithms using the flocking technique for OFDMA-based wireless mesh networks. We propose a time and frequency synchronization model taking into account channel propagation delays existing in wireless mesh networks, and analyze the convergence condition of the proposed synchronization algorithm. Convergence performance of the proposed synchronization algorithm is analyzed via computer simulation in terms of synchronization parameters in the time and frequency synchronization model.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.473-482
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• 2001

Integrated heterogeneous database systems provide the unified interface for users and applications today in order to access the underlying diverse data sources located in different sites. The multiple heterogeneous data sources have the different and specialized data structures and transaction processing capabilities. Because of local autonomy, the local system does not have the capability of cooperation to control the global transaction. Hence designing the global transaction manager with supporting the global serializability is difficult task. To resolve the well-known indirect conflict, we define the global transaction model by using the characteristics of global integrity constraints. And then we propose the site-locking operation and its protocol to manage the global transaction. The correctness and analysis of our site-locking protocol is proved and performance gain over the related other methods is also estimated in this paper.

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.510-516
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• 1997

반응성RF 마그네트론 스퍼터링 법으로 상온에서 c-축으로 우선 배향된 AIN 박막을 여러 기판 위에 증착하였다. SiO$_{2}$/Si, Si$_{3}$N $_{4}$Si, Si(100), Si(111)그리고 $\alpha$-AI$_{2}$O$_{3}$(0001) 기판에서 AIN(0002)로킹커브 피크의 표준편차는 각각 2.6˚, 3.1˚2.6˚, 2.5˚ 그리고 2.1˚ 의 값을 나타내었다. $\alpha$-AI$_{2}$O$_{3}$(0001) 기판에 증착된 AIN박막은 epitaxial 성장을 나타내었다. Si기판에 증착된 AIN박막에서 측정된 비저항과 1MHz 주파수에서 측정된 유전상수의 값은 각각 $10^{11}$Ωcm와 9.5였다. IDT/AIN/$\alpha$-AI$_{2}$O$_{3}$(0001)구저를 갖는 지연선 소자의 표면 탄성과 특성을 측정하였다. 상 속도, 전기기계 결합계수 그리고 전파손실은 H/λ가 0.17-0.5 범위에서 각각 5448-5640m/s, 0.13-0.17% 그리고 0.41-0.64dB/λ의 값을 나타내었다.다.

• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.302-311
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• 2018

Using cylindrical paper pot nursery method, three kinds of commercial tomatoes 'Dafnis', 'DOTAERANG DIA' and 'Maescala' were grafted onto a commercial rootstock 'B blocking'. From 10 to 40 days after graft-take, growth traits of seedlings were investigated by 0.5, 1.0 and 2.0S treatments of standard nutrient solution(S) for seedling growth, and top to root ratio(TRR), compactness(CP) and Dickson Quality Index(DQI) were calculated. Two weeks after transplanting of the seedlings under three different night temperature targeting to 10, 15, and $25^{\circ}C$, which were not precisely controlled, the relative growth rate (RGR) was investigated. The quantitative growth traits of grafted seedlings increased with increasing fertilizer concentration, and various range of seedling size could be produced. Compactness and DQI were significantly regressed (Adj $R^2=0.9480$). Short-term RGR after transplanting was higher at 1.0S treatment of standard nutrient solution at the seedling age of 30 days and 40 days after graft-take(DAGT). DQI and RGR were significantly regressed linearly at respective fertigation strength. Specially the diminishing slope of RGR was lower at 1.0S fertigation strength with the increase of DQI than others. The results indicate that DQI could be applied as a quality index of grafted tomato seedlings and the relation analysis between DQI and short-term RGR also could be used to determine the good quality seedlings of grafted tomato grown in cylindrical paper pot.