• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.341-344
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• 2000

본 논문에서는 stepper motor 나 BLDC motor를 구동하기 위하여, 최신 microcontroller, PC, control IC board 등으로 구성된 새로운 시스템을 설명하는데 목적이 있다. 이 시스템에서는 인터넷으로 전송되는 microcontroller program를 이용하여 SPDS(smart power development system)을 구동시키고, 이로 인하여 dedicated drive IC를 제어하여 stepper 또는 BLDC motor를 구동시키게 되며, 원격지에 있는 사용자의 motor를 제어함을 목표로 하고 있다. 본 논문에서 사용된 drive IC 는 SGS-Thomson 제품으로써 stepper motor 용으로 L6205/6/7/8, 그리고 BLDC motor 용으로 L6235 이다. SPDS는 ST92F120 16-bit microcontroller를 사용하고 있다. 이 논문에서는 인터넷 Protocol Converter에 의한 프로그램 전송, Operating System Program 및 Driver Software Program의 생성 및 구성, Drive IC의 구성 및 특징, SPDS 의 hardware 및 software 의 구성 등에 대하여 설명한다.

• Journal of Korea Foundry Society
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• v.20 no.2
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• pp.129-140
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• 2000

This study aims at the phase-field modeling of the phase transformation in graphitization of the cast iron. As the first step, we constructed a phase-field model including the phases with negligible solubility. Under the dilute regular solution approximation, a simplified version of the phase-field model was obtained, which can be used for the phase transformation related with the stoichiometric phases. The results from the numerical calculation of the phase-field model was in good agreement with the exact analytic solution. The compositional shift due to Gibbs-Thomson effect can be reproduced within 0.5% error in the numerical calculation. The interface velocity, whereas, in numerical calculation of phase-field model appeared to be 15% larger than that from the analytic solution. This error is due to the shift of the interface position in phase-field model from the position with ${\phi}=0.5$.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.910-915
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• 2003

This paper describes the design of a 2-phase stepping motor driver using CPLD(Complex Programmable Logic Device). The driver IC such as L297 (SGS-Thomson Microelectronics), which is mostly used has some problems in PWM control because of the switching noise of power MOSFETs. It causes current ripple and acoustic noise. To improve theses characteristics, we proposed a new current control method that the output PWM frequency is almost constant using a digital filter. Also we proposed constant current method for 1-2 phase(half step) excitation. The proposed method is implemented with CPLD(Xilinx, XC9572-PC44). Experimental results show the effectiveness of the proposed method.

• Animal Systematics, Evolution and Diversity
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• v.31 no.2
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• pp.77-85
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• 2015

We reviewed South Korean species of the genus Apechthis and confirmed four species and two subspecies. In this genus, four species and one subspecies have been reported from the Eastern Palaearctic region, two species and one subspecies were from South Korea. Additionally, we report two species and one subspecies, Apechthis compunctor orientalis Kaspryan, 1973, Apechthis quadridentata (Thomson, 1877) and Apechthis rapae (Uchida, 1925), which were newly recorded for the first time from South Korea. A key to South Korean species of the genus Apechthis, redescriptions of newly recorded species and subspecies and digital images of South Korean Apechthis are provided.

• Animal Systematics, Evolution and Diversity
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• v.37 no.1
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• pp.39-51
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• 2021

The South Korean species of family Proctotrupidae Latreille, 1802 (Hymenoptera: Proctotrupoidea) are studied. Here, seven proctotrupid species are newly added in the South Korean fauna: Cryptoserphus aculeator (Haliday), Disogmus basalis (Thomson), Mischoserphus arcuator (Stelfox), M. samurai (Pschorn-Walcher), Nothoserphus scymni (Ashmead), Proctotrupes gravidator (Linnaeus), and Tretoserphus laricis (Haliday). Which of them, four genera belonging to the tribes Cryptoserphini and Proctotrupini (Cryptoserphus, Mischoserphus, Proctotrupes, and Tretoserphus) are also newly recorded from South Korea. A key to genera of South Korean Proctotrupidae, diagnosis, photographs, distribution, and recorded hosts for each species are presented. All proctotrupid specimens were kept in the collections of the Geolim Entomological Institute, Daegu, South Korea.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.60-63
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• 2009

Most J-T (Joule-Thomson) refrigerators use a Giaque-Hampson type heat exchanger due to its excellent thermal performance and compactness. The cryoprobe (cryosurgical probe) treating prostate cancer usually has a dimension of 17 gauge (1.6 mm diameter), so it does not have enough space to bear a Giaque-Hampson type heat exchanger. In this paper, the triplet heat exchanger is adopted as the heat exchanger of cryoprobe, and the performance is investigated with an experimental test. The result shows that the triplet heat exchanger can be substituted for Giaque-Hampson type heat exchanger in the application of cryosurgery.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.43.3-43.3
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• 2019

A coronal mass ejection (CME) mass is generally estimated by the total brightness measured from white-light coronagraph observations. The total brightness are determined from the integration of the Thomson scattering by free electrons of solar corona along the line of sight. It is difficult to estimate the masses of halo CMEs due to the projection effect. To solve this issue, we construct a synthetic halo CME with a power-law density distribution (ρ = ρ₀r^-3) based on a full ice-cream cone model using SOHO/LASCO C3 observations. Then we compute a conversion factor from observed CME mass to CME mass for each CME. The final CME mass is determined as their average value of several CME masses above 10 solar radii. Our preliminary analysis for six CMEs show that their CME mass are well determined within the mean absolute relative error in the range of 4 to 15 %.

• Animal Systematics, Evolution and Diversity
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• v.39 no.3
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• pp.92-98
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• 2023

Larvae of shoot flies are known to live on decaying plants or to infest the stems of wild and crop plants. Among them, some species are economically very important pests that damage fruits or cereal crops in Old world tropics and subtropics. In Korea, three species, Atherigona orientalis, A. oryzae, and A. soccata, are managed as quarantine pests. To date, a total of five species, A. (Acritochaeta) orientalis Schiner, A. (Atherigona) bifurca Suh and Kwon, A. (A.) biseta Karl, A. (A.) falcata (Thomson) and A. (A.) oryzae Malloch, including two quarantine pests, have been recorded in Korean fauna. During the survey of Korean houseflies, the authors discovered two new unrecorded species, A. (A.) miliaceae Malloch and A. (A.) reversura Villeneuve. The diagnoses and illustrations of these species are provided in addition to the key to the Korean Atherigona species.

• Design & Manufacturing
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• v.17 no.3
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• pp.61-66
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• 2023

In this study, we developed a simulation methodology for a technology that rapidly cools molds by directly spraying them with CO₂ in its liquefied gaseous state. Initially, a simulation verification process was conducted using ANSYS Fluent's heat transfer analysis based on temperature values measured in prior research experiments, ensuring a comparable temperature could be calculated. Subsequently, the validated analysis method was employed to evaluate design factors that exert the most significant influence on cooling. An evaluation was conducted based on three factors: part thickness, mold thickness, and the melting temperature of material. Using a full factorial design approach, a total of 27 analyses were completed and subsequently calculated through analysis of means. The impact assessment was carried out based on the temperature values at the product's core. The results indicated that the thickness of the mold had the highest influence, while the melting temperature of material had the least.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.8
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• pp.695-700
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• 2014

In the present study, the melting temperature depression of Sn nanoparticles manufactured using the modified evaporation method was investigated. For this purpose, a modified evaporation method with mass productivity was developed. Using the manufacturing process, Sn nanoparticles of 10 nm size was manufactured in benzyl alcohol solution to prevent oxidation. To examine the morphology and size distribution of the nanonoparticles, a transmission electron microscope was used. The melting temperature of the Sn nanoparticles was measured using a Differential scanning calorimetry (DSC) which can calculate the endothermic energy during the phase changing process and an X-ray photoelectron spectroscopy (XPS) used for observing the manufactured Sn nanoparticle compound. The melting temperature of the Sn nanoparticles was observed to be $129^{\circ}C$, which is $44^{\circ}C$ lower than that of the bulk material. Finally, the melting temperature was compared with the Gibbs Thomson and Lai's equations, which can predict the melting temperature according to the particle size. Based on the experimental results, the melting temperature of the Sn nanoparticles was found to match well with those recommended by the Lai's equation.