• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.978-981
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• 1999

In this paper, an improved integer-N frequency synthesizer that can be synthesized into smaller channel space than input signal frequency is presented. The proposed frequency synthesizer also has an characteristics of fast phase locking time. The frequency synthesizer performed in the manner that it divides various outputs of different phases in VCO by means of dividers that have different control signals respectively and then add the divided signal. In order to confirm the characteristics of proposed frequency synthesizer, behavioral and SPICE simulations are performed using C-language and HSPICE respectively.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.86-89
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• 1987

This paper treats with the design and fabrication of a frequency synthesizer for the generation of intermediate frequency of a HF band transceiver. The synthesizer is designed to control frequencies using a phase-locked loop and it is shown that method improved the performance of frequency accuracy and locking time then that of the crystal-reference system.

• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.125-134
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• 1994

In real-time database systems, transactions's commitment done before the given deadlines is more important than just getting the maximum throughput. Transactions missing the given deadlines are no longer meaningful in real-time applications. Therefore, there is a need for new transaction processing models to meet the given deadlines in real-time database applications, because moat conventional transaction models are not designed to meet deadlines. In this paper we propose a new transaction models which uses multiple versions of a data item. The model uses read-from graphs and dynamic reorder of transactions to meet deadlines. A read-from graph contains the past read semantics of read operations and support the model to decide which database operation to be taken. Then, we show simulation results comparing the proposed model with other transaction models such as two phase locking model and the optimistic concurrency control model.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.89-99
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• 1997

The application for real-time database systems must satisfy timing constraints. Typically the timing constraints are expressed in the form of deadlines which are represented by priorities to e used by schedulers. In any real-time applications, since the system maintains sensitive information to be shared by multiple users with different levels of security clearance, security is another important requirement. As more advanced database systems are being used in applications that need to support timeliness while managing sensitive information, protocols that satisfy both requirements need to be developed. In this appear, we proposed a new priority-driven secure multiversion locking (PSMVL) protocol for real-time secure database systems. The schedules produced by PSMVL are proven to e one-copy serializable. We have also shown tat the protocol eliminates covert channels and priority inversions. The details of the protocol, including the compatibility matrix and the version selection algorithms are presented. the results of the performance comparisons of our protocol with other protocols are described.

• Clinics in Shoulder and Elbow
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• v.11 no.2
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• pp.137-142
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• 2008

Purpose: To evaluate the clinical and radiographic results of the treatment of a proximal humerus fracture with a locking compression plate(LCP). Materials and Methods: This study reviewed the results of 24 cases of a proximal humerus fracture treated with a LCP from January 2005 to April 2007, after a follow up of more than 12 months. There were 8 males and 16 females with a mean age of 68.9(33-90) years. The clinical results were evaluated using the Neer's evaluation criteria, and the radiographic results were evaluated using the bone union time and Paavoleinen method. Results: The mean time for bone union was 11.9 weeks. Using the Neer's functional evaluation, 21 cases of the 24 patients (87%) showed excellent or satisfactory results. Twenty two cases (91%) showed good results according to the Paavoleinen method. The complications encountered were metal failure (1 patient), AVN of the humeral head (1 patient) and joint stiffness (1 patient). Conclusion: The LCP demonstrated good results in the treatment of a proximal humerus fracture and has relatively fewer complications than other internal fixators.

• Journal of Korean Foot and Ankle Society
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• v.13 no.2
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• pp.162-168
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• 2009

Purpose: To evaluate the efficiency of the minimally invasive percutaneous plate osteosynthesis (MIPPO) with locking compression plate (LCP) for distal tibial metaphyseal intra-articular fracture compared with extra-articular fracture. Materials and Methods: From February 2006 to June 2008, 21 patients with distal tibia metaphyseal intra-articular fracture and 20 patients with extra-articular fracture were treated operatively by MIPPO technique with LCP and followed for at least one year. In the group with intra-articular fracture, mean age was 48.85 years old and a mean follow-up was 15 months. In the other group with extra-articular fracture, mean age was 52.35 years old and a mean follow-up was 14.5 months. The type of fracture was evaluated using the AO/OTA classification and open-fractures were according to the Gustilo-And gron classification. Radiologic evaluation with fracture healing and tibial alignment, clinical evaluation with Olerud and Molander ankle score and restriction of motion were done for treatment. Results: According to AO/OTA classification, There were 21 type A, 15 type B, 5 type C. Average union time of the intra-articular fracture (type B, C) was 18.7 weeks. Average union time of the extra-articular fracture (type A) was 17.1 weeks. All fractures were healed without malunion. There were no difference of mean restriction angle between intra-articular fracture (ankle dorsiflexion was 3.57 degree, plantar-flexion was 5.95 degree) and extra-articular fracture (ankle dorsiflexion was 3 degree, plantar-flexion was 3.75 degree). There were no difference of Olerud and Molander ankle score between them as a mean score of intra-articular and extra-articular was 89.25, 91.25 each other. As a complication, there were 3 case of skin necrosis, 8 case of discomfortable skin tenting by plate and 1 superficial infection, but could be healed by conservative care. Conclusion: MIPPO technique, combined articular reduction, with LCP of distal tibial metaphyseal fracture was a good method with high functional recovery.

• Journal of Korean Foot and Ankle Society
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• v.17 no.2
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• pp.130-135
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• 2013

Purpose: Preshaped Locking compression plate(LCP) has holes with fixed angle between screw and plate and have advantage firm fixation because it has stability of angular and axial deformity. We evaluated usefulness of LCP after open reduction and internal fixation in distal fibular fracture. Materials and Methods: Between December 2011 and May 2012, 23 patients with fracture of distal fibula were followed up at least 12 months underwent open reduction and internal fixation with LCP. There were 15 males and 8 females with a mean age 39.8(20~69) years. According to Danis-Weber classification, there were 20 cases of type B and 3 cases of type C. There were 13 cases of isolated lateral malleolus fractures, 1 case of bimalleolar fracture, 6 cases of trimalleolar fractures and 3 cases of distal tibia fractures with proximal fibula fracture. Intraoperatively, we assessed whether preshaped LCP fit lateral margin of distal fibula or not and evaluated quality of reduction and postoperative complications. The cases were analyzed by radiological bone union time and clinical results according to the criteria of Meyer Results: Of all cases, complete bone union was achieved and average radiological bone union time was 7.3(6~12) weeks. The clinical results were excellent in 18 cases(78%), good in 5 cases(22%). There were 5 cases of plate with 3 holes, 13 cases of plate with 4 holes, 2 cases of plate with 5 holes, 1 case of plate with 6 holes and 2 cases of plate with 7 holes. The average number of screws at proximal fragement was 2.5 and at distal fragment was 3.5. In 14 cases (60.8 %), we needed re-bending of plate because the distance between plate and lateral cortical margin of distal fibula was more than 5 mm at anteroposterior X-ray after reduction. All cases have anatomical reduction and there were no complications of wound infections. There were no complaint about hardware irritation. Conclusion: At fractures of distal fibula,preshaped LCP had a excellent stability although far cortex was not fixed with screw and bending of plate. And there are less complications of hardware irritation and wound problems. But, Some complement would be needed because there were no complete fitting between precontour of LCP and lateral cortical margin of distal fibula.

• The KIPS Transactions:PartA
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• v.10A no.3
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• pp.247-254
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• 2003

This paper describes a Delay Locked Loop (DLL) with low supply voltage and wide lock range for Synchronous DRAM which employs Double Data Rate (DDR) technique for faster data transmission. To obtain high resolution and fast lock-on time, a new type of phase detector is designed. The new counter and lock indicator structure are suggested based on the Dual-clock dual-data Flip Flop (DCDD FF). The DCDD FF reduces the size of counter and lock indicator by about 70%. The delay line is composed of coarse and fine units. By the use of fast phase detector, the coarse delay line can detect minute phase difference of 0.2 nsec and below. Aided further by the new type of 3-step vernier fine delay line, this DLL circuit achieves unprecedented timing resolution of 25psec. This DLL spans wide locking range from 500MHz to 500MHz and generates high-speed clocks with fast lock-on time of less than 5 clocks. When designed using 0.25 um CMOS technology with 1.8V supply voltage, the circuit consumes 32mA at 500MHz locked condition. This circuit can be also used for other applications as well, such as synchronization of high frequency communication systems.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.2
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• pp.37-44
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• 2008

This paper presents a 5.8 GHz PLL using high-speed ring oscillator for WLAN. The proposed ring oscillator has been designed using the negative skewed delay scheme and for differential mode operation. Therefore, the oscillator is insensitive to power-supply-injected noise, and it has the merit of low 1/f noise because tail current sources are not used. The output frequency ranges from 5.13 to 7.04 GHz with the control voltage varing from 0 to 1.8 V. The proposed PLL circuits have been designed, simulated, and proved using 0.18 um 1.8 V TSMC CMOS library. At the operation frequency of 5.8 GHz, the locking time is 2.5 us and the simulated power consumption is 59.9 mW.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.10
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• pp.914-924
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• 1991

It has been generally used for PLL(Phase Locked Loop) to be synthesized randomly chosen frequency state, but the PLL locking time was inevitable element. A direct digital synthesizer. Which makes output frequency directly in sine wave by a phase accumulating method, could be leiminate the defect, although a phase distortion in frequency spectrum. In order to improve this disadvantage, the phase accumulating method is reconsidered in the side of he output wave formula expression. A new mechanism is proposed, and it is constructed by a most suitable logic elements. The spectrum of synthesized sine waveform is simulated and compared with a measured value, and it’s the coherence frequency hoppong state with the PN(Pseudo Noise) code sequence is confirmed. In this results, the power levels of phase distortion harmonics are decreased to 10~25dB and bandwidths are increased to 420kHz.