• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.27-33
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• 2002

This paper proposes a method to drive an AC plasma display panel(PDP) with a significantly improved contrast ratio. In the proposed method, during the first sub-field of one frame, all PDP cells are reset by the ramp waveform, and during the other sub-fields, only the cells turned on in the previous sub-field are reset. No light is emitted during the reset period of every sub-field except the first sub-field. For a 10-bit picture, the luminance of the dark level for the proposed method is 10 times lower than that for the conventional method, in which the ramp waveform for the reset is used in every sub-field. Accordingly, the contrast ratio for the proposed method is 10 times higher than that for the conventional method. For the 10-bit picture, the measured contrast ratio was about 3080:1 for the proposed method and about 285:1 for the conventional method, resulting in 10.8 times increase in the contrast ratio. This result shows that the proposed method can realize an image with high contrast ratio.

• Journal of Broadcast Engineering
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• v.5 no.2
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• pp.140-158
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• 2000

Testing of terrestrial Digital TV(DTV) broadcasting in Seoul and Kyung-gi region was started in May 1999. Tasks of the committee for DTV technical evaluation were to implement test procedures for DTV transmitting systems, to analyze various technical aspects of DTV and to complete a field test. This paper summarizes the field test results. The field test vehicle was designed and constructed to measure field data. We chose over 200 test points to verify the receiving status of DTV signals and compared them with the analog TV signals at the same site. The results showed stable and satisfactory reception of DTV signals over 70%. The system performance index was over 80%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.373-378
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• 2002

This paper presents the results of an electromagnetic field uniformity of a triangular reverberation chamber that can be used alternatively for analysis and measurement of electromagnetic interference and immunity test. Equilateral triangular reverberation chamber and Schroeder diffusers were designed and fabricated for this purpose. FDTD simulation method was applied to analyze the field distribution inside of two different types of reverberation chambers. As a result, the electromagnetic field uniformity was improved inside of triangular reverberation chambers, and the measured field uniformity was improved by 1 ∼4 ㏈ compared to the ones without diffusers.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.558-574
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• 2014

The number of fatty liver patients is sharply growing due to the rapid increase in the incidence of metabolic syndrome, which can lead to diseases such as abdominal obesity, hypertension, diabetes, and hyperlipidemia. Early diagnosis requires examinations using magnetic resonance imaging (MRI), wherein quantitative analyses are implemented through a professional water-fat separation method in many cases, as the intensity values of the areas of interest and non-interest are considerably similar or the same. However, such separation method generates inaccurate results in high magnetic fields, where the inhomogeneity of the fields increases. To overcome the limits of such conventional fat quantification methods, this paper proposes a field map estimation method that is effective in high magnetic fields. This method generates field maps through echo images that are obtained using the existing IDEAL sequences, and considers the wrapping degree of the field maps. Then clustering is performed to separate calibration areas, the least square fits based on the region growing method schema of the separated calibration areas, and the histograms are adjusted to separate the water from the fats. In experiment results, our proposed method had a superior fat detection rate of an average of 86.4%, compared to the ideal method with an average of 61.5% and Yu's method with an average of 62.6%. In addition, it was confirmed that the proposed method had a more accurate water detection rate of 98.4% on the average than the 88.6% average of the fat saturation method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.96-104
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• 2007

In this paper, the field solver based deembedding technique for the on-chip inductors to deembed the pad and surrounding ground effect was described, and the results from field solver based deembedding techniques and measurement based matrix calculation method were compared. In addition, LNA circuit is designed by using deembedded inductors and fabricated by using standard $0.25{\mu}m$ CMOS process, in the range over the 2.5GHz it shows the good agreements between measurement and simulation results when the proper deembedding was adapted. Supposed deembedding techniques can be used to get the pure on-chip devices's values and adapted to design accurate RFIC circuit design.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.82-83
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• 2000

초고속 광통신 시스템 구현에 있어서 핵심기술의 하나인 광섬유의 색분산 제어와 함께 그 정확한 측정을 위한 여러 방법들이 연구되어 왔으나, 기존의 방법들은 실험 장치가 복잡하고 광대역의 광원을 필요하므로 저가의 시스템 구현 및 실제적 응용이 어렵다.$^{(1)}$ 실제 시스템에 장착되어 있는 필드에서 응용 될 수 있기 위해서는 소형이며 온도와 같은 외부 환경에 민감하지 않은 시스템을 필요로 한다. 본 연구에서는 실제필드에서의 광섬유에 대한 정확한 색분산 측정을 위한 시스템 개발을 목적으로 이득스위칭된 다모드레이저 및 고분산광섬유(Highly Dispersive Fiber)를 이용한 색분산 측정시스템을 제안한다. (중략)

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.31-37
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• 2002

전자파 잔향실(Reverberating Shielded Enclosure)의 개념은 전자파 차폐실(Shielded Enclosure)에서 얻어진 측정결과를 개선하기 위하여 1968년도에 제안되었다. 이후 Reverberating 또는 Mode-Stirred Chamber는 EM Immunity 측정뿐만 아니라 EMI측정에서도 많이 적용되어 왔지만, 국제 표준 방식으로 적용되어 오지 못하다가 최근 EMI 복사 전력 측정 및 EM Immunity 측정시설로 유용하게 사용될 수 있다는 점이 부각되어 국제 표준 방식으로 적용하자는 분위기가 무르익어 이에 대한 활발한 논의가 계속되어 오고 있다. 이러한 전자파 잔향실을 이용하여 EMI 및 EMS 시험을 실시할 수 있는 방법을 규격화시키자는 제안이 '96년 프랑스 Mandelieu 국제 전자파 장해 특별위원회(CISPR:International Special Committee on Radio Interference)회의에서 검토된 후 '97년 일본 Yokosuka CISPR 회의에서 정식의제로 채택되었다. 이 안건에 대하여 대부분의 국가들이 제안 취지에 찬성하여 NWIP(New Work Item Proposal) 문서가 각국에서 회람되었다. 초기 전자파 잔향실은 전자파 장해 및 복사 내성 측정을 위한 대용시험 시설로서 1968년 미국 Mendes에 의해 전자파 차폐실 구조에 Stirrer를 이용하여 필드의 균일도를 확보할 수 있다는 전자파 잔향실 개념이 처음으로 제안되었다. 이후 이 분야의 연구는 미국 표준 기술 연구소(NIST: National Institute of Standard and Technology)등에서 연구가 활발히 진행되고 있으며, 국제 표준화 기구인 CISPR에서 전자파 장해 및 내성 시험을 위한 대용시험 시설로서 활용하기 위하여 규격 작업이 진행중에 있다. 또한 최근 전자파 장해 방지를 위한 규제 주파수가 1∼18㎓ 까지 확장됨에 따라 이 주파수 대역에서 시험장으로 활용할 수 있는 전자파 잔향실이 새롭게 부각되고 있다. 전자파 잔향실은 기본적으로 공진 모드를 활용하기 때문에 일정한 크기의 잔향실 내부에서 전자파 균일성을 확보할 수 있는 모드 수에 의해 하한 주파수가 결정되며 충분한 모드 분포상태에서 Stirrer를 사용하여 필드 경계를 이동시킴으로서 확률적으로 균일한 필드분포를 확보하게 된다. 주파수가 증가함에 따라 모드수는 증가하기 때문에 하한 주파수 이상의 대역에 대한 시험시설로 활용할 수 있으며, 특히 ㎓ 대역에서 사용하기에 적합한 대용시험시설이라고 볼 수 있다.

• Journal of the Korean Society for Library and Information Science
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• v.35 no.4
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• pp.97-122
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• 2001

This empirical study investigated the effect of choice of record field(s) upon which to search on retrieval performance for a large operational bibliographic database. The query terms used in the study were identified algorithmically from each target set in four different ways: (1) controlled terms derived from index term frequency weights, (2) uncontrolled terms derived from index term frequency weights. (3) controlled terms derived from inverse document frequency weights, and (4) uncontrolled terms based on universe document frequency weights. Su potable choices of record field were recognised. Using INSPEC terminology, these were the fields: (1) Abstract. (2) 'Anywhere'(i.e., ail fields). (3) Descriptors. (4) Identifiers, (5) 'Subject'(i.e., 'Descriptors' plus Identifiers'). and (6) Title. The study was undertaken in an operational web-based IR environment using the INSPEC bibliographic database. The retrieval performances were evaluated using D measure (bivariate in Recall and Precision). The main findings were that: (1) there exist significant differences in search performance arising from choice of field, using 'mean performance measure' as the criterion statistic; (2) the rankings of field-choices for each of these performance measures is sensitive to the choice of query : and (3) the optimal choice of field for the D-measure is Title.

• Journal of Broadcast Engineering
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• v.10 no.2
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• pp.221-237
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• 2005

This paper presents and analyzes field test results of Equalization Digital On-Channel Repeater (EDOCR) using ATSC(Advanced Television Systems Committee) terrestrial digital TV broadcasting system. In the field test, according to EDOCR On/Off, types of antennas and receivers we measured reception possibility, C/N(Carrier to Noise Ratio), reception power, noise and input margin at each test point. By the field test results, the reception rate of the receiver manufactured in 2004 was $33\%$ when EDOCR is off and directional antenna is used. However, the reception rate was $100\%$ when EDOCR is on. In addition, the noise margin, which determines reception quality was increased at least 6 dB, so that it is capable of constructing SFN(Single Frequency Network) using the EDOCR.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.9 no.1
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• pp.221-240
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• 1998

This study concerns information quality of the database which has been produced in the ASKERIC database. The measures used in this study were accuracy of the records. consistency, completeness and currency. Accuracy was measurred in terms of the keywords used in different ways in the US and Britain and the spelling errors in the records. Consistency was measured in terms of 'see also' and 'see reference' mechanism and character capitalization. Completeness was measured as follows： completeness of the search fields in the record and relevance of search fields. Currency was measured using the publication date. The experimental result showed that ERIC databases had some errors in terms of accuracy. consistency. completeness and currency. However, continuous striving for the automatic error checking functions and the policy of feedback from users have contributed to the improvement of the quality in ERIC databases.