• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.191-198
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• 2019

In this paper, we implemented the prevention of oil mixing accidents caused by stereotypes or novice drivers at gas stations. After the CO gas concentration of the fuel tank is measured using the MQ-9 gas sensor, the gasoline and diesel are distinguished from each other. This is decided by using a servomotor to lock of the fueling nozzle to prevent the mixing of oil. In addition, car washes time display is implemented by using infrared sensor to save the time and to provide convenience for customers who want to wash car after fueling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7C
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• pp.706-714
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• 2009

In this paper, we proposed a burst mode AGC loop and preamble detector applicable for VDL(VHF Digital Link) mode-2 using D8PSK modulation scheme and the performance analysis of proposed schemes is described. Generally the AGC scheme can be divided into two types, continuos and burst mode AGC. The continuos mode is performed well only with an analog feedback AGC loop. But the analog feedback AGC loop is not suitable for burst mode since its gain lock time is more than preamble duration, which causes the preamble detector misses preamble. Hence a fast digital AGC loop is required for burst mode. Also the AGC loop has to be designed with full gain during idle time to detect bursts although the signal level is very low. If the time to acquire gain lock is slow, the preamble detector fail to detect burst due to saturation of a lot of preamble samples. The receiver performance might be down even if the burst was detected because the preamble is used to estimate several parameters need to demodulation at receiver. In this paper we analysed relationships between the AGC loop and preamble detector. we present an AGC loop and preamble detector in burst mode.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.11-18
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• 2000

In this paper we present a new extensible model based upon the concept of subtransactions in real-time transaction systems. The nested transaction model originally proposed by J. Moss is extended for real-time uniprocessor transaction systems by adding explicit timing constraints. Based upon the model, an integrated concurrency control and scheduling algorithm is developed, that not only guarantees timing constraints of a set of real-time transactions but also maintains consistency of the database. The algorithm is based on the priority ceiling protocol of Sha et al. We prove that the Real-Time Nested Priority Ceiling Protocol prevents unbounded blocking and deadlock, and maintains the serializability of a set of real-time transactions. We use the upper bound on the duration that a transaction can be blocked to show that it is possible to analyze the schedulability of a transaction set using rate-monotonic priority assignment. This work is viewed as a step toward multiprocessor and distributed real-time nested transaction systems. Also, it is possible to be extended to include the real-time multimedia transactions in the emerging web-based database application areas.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.548-552
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• 2003

In the braking system, the friction force is the most important factor of the design. For long time, many researchers have been strived for getting the exact friction coefficients. But the friction coefficients are affected by the road condition and changed by lots of parameters, such as normal force and characteristics between two contacted materials, temperature, etc. For the development of ABS of the aircraft, HILS(Hardware-In-the-Loop-Simulation) test and dynamometer test was carried out. For the calculation of the friction coefficients, the wheel moments were measured using the load cell mounted on the housing of the wheel. The test conditions were dry and greasy, as the 0.7 and 0.4 in friction coefficient, respectively. In this paper, the test results of the friction coefficients were represented and the improvement method was suggested.

• Journal of Information Technology Applications and Management
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• v.12 no.4
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• pp.59-70
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• 2005

Flash memories are one of best media to support portable computer's storages in mobile computing environment. The features of non-volatility, low power consumption, and fast access time for read operations are sufficient grounds to support flash memory as major database storage components of portable computers. However, we need to improve traditional transaction management scheme due to the relatively slow characteristics of flash operation as compared to RAM memory. in order to achieve this goal, we devise a new scheme called Flash Two Phase Locking (F2PL) scheme for efficient transaction processing. F2Pl improves transaction performance by allowing multi version reads and efficiently handling slow flash write/erase operation in lock management process. We also propose a simulation model to show the performance of F2PL. Based on the results of the performance evaluation, we conclude that F2PL scheme outperforms the traditional scheme.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.108-117
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• 1995

The primary purpose of this extensive test effort was to observe real-time operational performance characteristics associated with automotive grade fuel utilized by piston engine powered light aviation aircraft. In fulfillment of this effort, baseline engine operations were established with 100LL aviation grade fuel followed by four blends of automotive grade fuel. A comprehensive sea-level-static test cell/flight test data collection and evaluation effort were conducted to review operational characteristics of a carbureted light aircraft piston engine as related to fuel volatility, fuel temperature, and fuel system pressure. Presented herein are results, data, and conclusions drawn from test cell engine operation as well as flight test operation on 100LL aviation grade and four blends of automotive grade fuel.

• Journal of information and communication convergence engineering
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• v.3 no.3
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• pp.142-145
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• 2005

In this paper, a new programmable DLL (delay locked loop) based clock synthesizer is proposed. DLL has several inherent advantages, such as no phase accumulation error, fast locking and easy integration of the loop filter. This paper proposes a new programmable DLL that includes a PFD(phase frequency detector), a LSI(lock status indicator), and a VCDL(voltage controlled delay line) to generate multiple clocks. It can generate clocks from 3 to 9 times of input clock with $2{\mu}s$ locking time. The proposed DLL operating in the frequency range of 300MHZ-900MHz is verified by the HSPICE simulation with a $0.35{\mu}m$ CMOS process.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.211-213
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• 1998

실시간 응용을 위한 데이터베이스 시스템은 시간 제약 조건을 만족시켜야 하며, 데이터 일관성을 유지해야 한다. 또한 다중레벨을 지원하는 보안 프로토콜은 cover channel의 생성을 방지하는 것이 중요하다. Son과 Mukkamala는 primary copy와 secondary copy를 사용한 SRT-2PL을 개발하였다. 이 프로토콜은 보안 레벨간의 불간섭(non-interference)을 지원하며, covert channel의 발생을 막을 수 있으며, 지연이 적고 취소가 적으므로 실시간 데이터베이스 시스템에서 보안을 유지하는데 사용될 수 있다. 그러나 secondary copy를 모든 데이터 오브젝트에 대해 항상 보존해야 하므로 작업공간의 낭비가 있고, 데이터의 갱신을 위해 update queue를 관리해야 하는 오버헤드와 그에 따른 예측성 결여가 문제점으로 나타난다. 따라서, 본 논문에서는 불간섭을 지원하여 covert channel의 발생을 방지하면서, 복사본의 유지 기간을 줄여 실시간 지원을 강화시키고, 예측성을 좀더 높인 개선된 SRT-2PL 실시간 데이터베이스 보안 프로토콜을 제안한다. 본 논문에서 제안하는 동적 복사 알고리즘은 트랜잭션의 동작에 따라 동적으로 복사본을 생성하여 레벨간의 불간섭을 제공함과 동시에, 복사본의 유지 기간을 줄여 작업공간의 낭비를 줄이고 예측성을 높일 수 있다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.684_685
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• 2009

A digital sampling algorithm that uses a two high resolution integrating Voltmeters which are synchronized by Phase Lock Loop (PLL) time clock for accurately measuring the parameters, active and reactive power, for sinusoidal power measurements is presented. The PLL technique provides high precision measurements, root mean square (rms), phase and complex voltage ratio, of the AC signal. The system has been designed to be used at the Korean Research Institute of Standards and Science (KRISS) as a reference power standard for electrical power calibrations. The test results have shown that the accuracy of the measurements is better than $10 {\mu}W/VA$ and the level of uncertainty is valid for the power factor range zero to 1 for both lead and lag conditions. The system is fully automated and allows power measurements and calibration of high precision wattmeters and power calibrators at the main power frequencies 50 and 60 Hz.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.63-70
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• 1989

This paper describes to design and to examine the mechanical characteristics of high frequency jet ventilator. The device consists of Phase lock loop(PLL) system, solenoid valve driving control part and Air regulating system. This study is carried out by changing several factors such as endotracheal tube(E.T. tube)diameter, injector cannula diameter, 1%, and frequency(breaths/mim.) having direct effects on the gas exchange as well as parameters of the entrained gas by venturi effects, so as to measure the tidal volume and minute volume. This system characteristics were as follows : 1) Frequency : 6-594bpm 2) Inspiration time : 1-99% 3) Variance of input air pressure : 1-30PSI.