• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1798-1799
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• 2011

In this paper, A new cost-effective and accurate input noise rejection method for High Speed Counter module of PLC (Programmable Logic Controller) is proposed. By using combination of simple additional logic circuit and the Timer Pulse function of general purpose MPU, Cost-effectiveness and improvement of accuracy of filtering function can be achieved. This proposed method is verified by simulation. This proposed method is much useful for simple industrial controller based on simple microprocessor because of simplicity, accuracy and low cost.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.270-273
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• 2000

A new phase shift PWM parallel-input/series-output modularized dual converter is proposed in this paper. This converter is operated with a fixed duty ratio and its output voltage is regulated by phase shift between each module. Since the operating duty ratio of each module is fixed it is sufficient to implement a simple open loop drive circuitry for each module and the cost of total system can be much reduced. The operation of the converter is analyzed in this paper and verified by computer simulation.

• Bulletin of the Korean Mathematical Society
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• v.56 no.6
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• pp.1617-1642
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• 2019

In this paper, we study a theory for the structure of ${\tau}_w$-Loewy series of modules over commutative rings, where ${\tau}_w$ is the hereditary torsion theory induced by the so-called w-operation, and explore the relationship between ${\tau}_w$-Loewy modules and w-Artinian modules.

• Honam Mathematical Journal
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• v.43 no.3
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• pp.403-416
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• 2021

It is known that the rank 2 stably free syzygy module P⁽²⁾ is not free. This algebraic fact was proved analytically, but this remarkable fact still lacks of a simple algebraic proof. The main purpose of this paper is to give a partially algebraic proof by making use of a theorem whose proof is quite topological, and the further properties of the module will be discussed.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.19-26
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• 2010

The most critical element in the real-time operation of RFID application programs that are suitable for the mobile environment is the RFID middleware, made exclusively for mobile handsets, which processes collected data on a real-time basis and sends only the useful information to the application client. In this paper, we intend to design and implement the Pet management system for optimized mobile RFID middleware that supports real-time data processing. The proposed Pet management system consists of registration module, retrieval module, communication module, and display module in order to display retrieval result from server. Also, the captured data in the PDA is transmitted to the server and another client system using the mobile application interface that supports the SOAP application access protocol.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.272-277
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• 2003

This paper reports the fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) cooling fan. A flexible PZT fan with distortion in a fluid transport system of comparatively simple structure which was mounted on a PCB in a parallel-plate channel($450{\times}80{\times}700mm^3$) accelerates surrounding fluid locally. Input voltages of 20-100V and a resonance frequency of 23Hz were used to vibrate the cooling fan. Input power to the module was 4W. The cooling effect using a PZT fan was larger than that of free convection. Fluid flow around the module were visualized by using PIV system. The temperature distribution around heated module were visualized by using liquid crystal film(LCF). We found that the flow type was y-shaped and the cooling effect was increased by the wake generated by a piezoelectric cooling fan.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.740-742
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• 2005

In the past, a mobile phone had only a function of communication. Recently, new functions such as an mp3 player and a camera are added in a mobile phone. For the application of a camera module to a mobile phone, the size of the camera module needs to become smaller than a general Digital Camera. Furthermore, it is also required that the performance of the camera module in a mobile phone be the same as that of a Digital Camera. In order to fulfill these requirements, the camera module should have functions such as Auto Focus, Zoom, the shutter and the aperture. Therefore, we introduce a simple and effective actuator and propose the shutter composed of solenoid.

• Communications of the Korean Mathematical Society
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• v.15 no.3
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• pp.453-467
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• 2000

For any S-flat module RM(which will be called endoflat) with a commutaitve ring R with identity, where S is the endomorphism ring RM, the fact that every epimorphism is an automorphism has been proved and the Jacobson Radical Rad(S) of S is described as follow; Rad(S) = { f$\in$S｜Imf=Mf is small in M} = {f$\in$S｜Imf $\leq$Rad(M)}. Additionally for any quasi-injective endo-flat module RM, the fact that every monomorphism is an automorphism has been proved and the Jacobson Radical Rad(S) for any quasi-injective endo-flat module has been studied too. Also some equivalent conditions for the semi-primitivity of any faithful endo-flat module RM with the open Jacobson Radical Rad(M) and those for the semi-simplicity of any faithful endo-flat quasi-injective module RM with the closed Socle Soc(M) have been studied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.2
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• pp.171-181
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• 1988

In this study, a packet voice/data terminal(PVDT) that services both voice and data in the packet-switched network is implemented. The software structure of the PVDT is designed according to the OSI 7 layer architecture. The discrimination of voice and data is made in the link layer. Voice packets have priority over data packets in order to minimize the transmission delay, and are serviced by a simple protocol so that the overhead arising form the retransmission of packets may be minimized. The hardware structure of the PVDT is divided into five modules; a master control module, a speech proessing module, a speech activity detection module, a telephone interface module, and an input/output interface module. In addition to the hardware implementation, the optimal reconstruction delay of voice packets to reduce the influence of delay variance is analyzed.

• Korean Journal of Mathematics
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• v.7 no.2
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• pp.215-218
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• 1999

We investigate characterizations of rings whose simple singular right R-modules are GP-injective. It is proved that if R is a semiprime ring whose simple singular right R-modules are GP-injective, then the center $Z(R)$ of R is a von Neumann regular ring. We consider the condition ($^*$): R satisfies $l(a){\subseteq}r(a)$ for any $a{\in}R$. Also it is shown that if R satisfies ($^*$) and every simple singular right R-module is GP-injective, then R is a reduced weakly regular ring.