• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.105-110
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• 2009

The On Line Electric Vehicles(OLEV) that can pick up inductive power from underground coils on driving with high efficiency have been developed this year, and is now proposed in this paper. The IPS(Inductive Power Supply) system consists of power supply inverters, power supply rails, pick up modules, and a regulator. There are 3 generations of IPS have been developed so far, and the $4^{th}$ generation IPS is being developed. The $1^{st}$ generation has been demonstrated this Feb. 27, which is equipped with mechanically auto tracking pick-up module with 1cm air gap, and showed 80% power efficiency. The $2^{nd}$ generation IPS applied to an 120kW (average)/240kW(peak) motor powered electric bus has 17cm air gap with 72% power efficiency. For the $2^{nd}$ generation IPS, the Power supply inverter has 440V, 3phase input and 200A @ 20kHz output. The test power supply rail of 240m long is segmented by 60m each, where newly developed core structure and power cable are constructed under the road covered with asphalt of 5cm thickness. The pick-up modules which consist of core, winding wire, and rectifiers are fixed to the bottom of the bus which can carry more than 40 passengers and can pick up max. 60kW. To remove parasitic component and to transfer maximum power between them resonant circuit topology is applied to the primary and secondary sides. The EMF level is below 62.5mG at 1.75m from the center of the road to meet the regulation. Several effective ways of reducing EMF levels have been developed. In addition, effective ways to solve problems related high frequency power cables buried in ground and it's proof from soil have been studied also. This development shows that the IPS system is capable of supplying enough power to the pick-up of OLEV and can reduce battery size, weight and cost, which means the IPS with OLEV is one of the best candidate for EV.

• Journal of Korean Society for Quality Management
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• v.50 no.2
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• pp.287-304
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• 2022

Purpose: The size of the salad consumption market has expanded since Covid-19, and continuous growth is predicted. Therefore, by extracting influential core purchasers in the salad consumption market and analyzing their purchasing behaviors and consumer types, this study intended to provide basic data for establishing a marketing strategy. Methods: The analysis data is the purchasing data of 576 people who have purchased salads between 2016 and 2020 (panel data of the Rural Development Administration), and in the social network analysis, the centrality structure was analyzed. Results: First, in the results of analyzing the causes of the rapid increase in salad consumption in 2020, it was found that the increase in consumption of new purchasers (n=102) had little effect. The existing consumer type (n = 474), which has been the majority of the salad consumption market so far, were consumers with stable income. However, the results of study indicated that the type of consumers has expanded since low-income class as well as high-income class increased consumption of purchasing salad. Second, in the results of analyzing the types of key purchasers with great influence in the salad consumption market, there was a difference from the results of frequency analysis in age, number of family members, existence/absence of children, and income decile. This suggests that there should be a difference between the type of customers according to the apparent quantitative figure and the actual influential purchasers. Third, in the results of analyzing the salad purchasing behaviors of core purchasers, the purchasing site for existing purchasers was large-scale marts and for new purchasers it was corporate-type supermarkets. Purchases were concentrated on Saturdays for both existing and new purchasers. As for the purchased products, existing purchasers had a high preference for products made of chicken, and new purchasers had a high preference for vegetable/fruit salad. In particular, in the results of purchased products by age group, in the case of 50s and 60s, it was an interesting result that there was a difference between the products purchased by the existing and new purchasers even though they were the same age. Conclusion: When establishing a marketing strategy in the salad consumption market, it is necessary to pay attention to the purchasing behavior of key buyers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1027-1033
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• 2013

In this work, a D-band imaging detector has been developed in a 65-nm CMOS technology for high frequency imaging application. The circuit was designed based on the resistive self-mixing of MOSFET devices. The fabricated detector exhibits a maximum responsivity of 400 V/W and minimum NEP of 100 $pW/Hz^{1/2}$ at 145 GHz. The chip size is $400{\mu}m{\times}450{\mu}m$ including the probing pads and a balun, while the core of the circuit occupies only $150{\mu}m{\times}100{\mu}m$.

• Journal of the Korean Society for information Management
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• v.23 no.1 s.59
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• pp.279-299
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• 2006

This study utilizes various approaches of machine learning in the process of automatically assigning descriptors to journal articles. The effectiveness of feature selection and the size of training set were examined, after selecting core journals in the field of information science and organizing test collection from the articles of the past 11 years. Regarding feature selection, after reducing the feature set using $x^2$ statistics(CHI) and criteria that prefer high-frequency features(COS, GSS, JAC), the trained Support Vector Machines(SVM) performed the best. With respect to the size of the training set, it significantly influenced the performance of Support Vector Machines(SVM) and Voted Perceptron(VTP). However, it had little effect on Naive Bayes(NB).

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.62-65
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• 2003

We considered of the efficiency for the Buck+Half bridge converter This converter has advantages of applications for a low output voltage, a high output current and a wide input voltage. Developed the Buck converter ratings and the Half Bridge converter ratings are 36$\~$72V Input and 22V/5A output, 19$\~$24v input and 3.3V/30A output, respectively. Buck converter is operated with zero voltage switching process to reduce the switching losses. The 80.1 $\~$97.6$\%$ of the efficiency is measured at 18.4 $\mu$H output filter inductance of Buck convertor. In Half Bridge convertor, the 86$\~$96.4$\%$ of the efficiency is measured at 100kHz switching frequency with PQI core.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.693-696
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• 2005

KIGAM (Korea Institute of Geoscience and Mineral Resources) launched a new project to develop the low-temperature geothermal water in the area showing high geothermal anomaly, north of Pohang city, for large-scale space heating. Surface geologic and geophysical surveys including Landsat 1M image analysis, gravity, magnetic, Magnetotelluric (MT) and controlled-source audio-frequency MT (CSAMT), and self-potential (SP) methods have been conducted and the possible fracture zone was found that would serve as deeply connected geothermal water conduit. In 2004, two test wells of 1.1km and 1.5km depths have been drilled and various kinds of borehole survey including geophysical logging, pumping test, SP monitoring, core logging and sample analysis have followed. Temperature of geothermal water at the bottom of 1.5km borehole reached over $70^{\circ}C$ and the pumping test showed that the reservoir contained huge amount of geothermal water. Drilling for the production well of 2 km depth is on going. After test utilization and the feasibility study, geothermal water developed from the production well is going to be provided to nearby apartments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.35-45
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• 2008

This paper present the Three-Level converter using IM(Integrated Magnetics) method for high power application. In power conversion system, magnetic components are important devices used for energy storage, energy transfer, galvanic isolation and filtering. The proposed Three-Level converter is to reduce the number of magnetic components using transformer integrated with output inductor. This paper proposes reluctance model base on the magnetic analysis for the Three-Level converter. Also, the secondary rectification was discussed by a single core transformer winding. A protype featuring 540[V] input, 48[V] output, 40[kHz] switching frequency, and 3[kW] output power using IGBT.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.100-110
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• 2006

This paper presents the demagnetization and iron loss analysis of the single phase Flux Reversal Machine. It has a magnetic configuration similar to the switched reluctance machine but with multipole permanent magnets of alternate polarity on each stator salient pole embraced by concentrated coils. But it can be demagnetized by sudden over current and core losses increase because switching frequency is getting faster. This paper show demagnetization of permanent magnet and iron loss characteristic, and proposed a solution.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.160-166
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• 2015

Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is $5.4{\mu}m$ noted at the frequency of 40 kHz. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.43-49
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• 2020

The growth of the AR/VR market due to the advent of the 4th Industrial Revolution begins with the development of the display industry. The development of OLED and flexible displays is further accelerated by the development of R2R technology. Micro-processing technology using a fast tool servo (FTS), the core technology in R2R processes, is making technological progress in increasingly diverse ways. This paper proposes a method to develop an FTS for horizontal driving and presents this method through experiments and analyses. To develop a swing-type FTS based on a seesaw motion, a rotational moment hinge structure was designed for each type, and research was conducted to determine an effective design method. A cantilever-based swing-type FTS was developed in two variations: one with single-side hinges and another with dual-side hinges. The parameters in the design of the swing-type FTS are rotational moment, natural frequency, and material selection. In conclusion, an FTS with a single-side hinge demonstrates the high performance required for micro processing.