• 전기의세계
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• v.34 no.9
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• pp.537-540
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• 1985

인체에 발생하는 여러 질환을 진단 및 치료하고 예후를 결정하는데 혈관의 분포 및 그 상태를 관찰하는 것은 극히 중요하다. 형관조영술의 진단적 기치 및 그 임상적 응용은 1950년대 부터 널리 인정되고 있다. 다만 조영제 주입에는 동맥의 천자 및 도관(Catheter)삽입이라는 비교적 침습적 방법에 의존하여 왔다. 최근 Computer의 도입으로 대표되는 전자기술의 발전 등으로 혈관 특히 동맥의 저농도 조영상을 전산처리로서 숫자화하여 증강, 가산 또는 감산시키는 기법이 개발되어 1970년대 후반에 이르러 임상적으로 응용되게 되었다. 이러한 전산화 감산 형과조영술(Digital Subtraction Angiography : DAS)은 종래의 혈관조영술의 기본 수기에 전산 시스템을 복합시킨 것으로 그 임상적 효과는 매우 큰 것이다.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.102-109
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• 2009

Purpose: Flash 3D (pixon(R) method; 3D OSEM) was developed as a software program to shorten exam time and improve image quality through reconstruction, it is an image processing method that usefully be applied to nuclear medicine tomography. If perfoming brain diamox perfusion scan by reconstructing subtracted images by Flash 3D with shortened image acquisition time, there was a problem that SNR of subtracted image is lower than basal image. To increase SNR of subtracted image, we use LEAP collimators, and we emphasized on sensitivity of vessel dilatation than resolution of brain vessel. In this study, our purpose is to confirm possibility of application of LEAP collimators at brain diamox perfusion tomography, identify proper reconstruction factors by using Flash 3D. Materials and methods: (1) The evaluation of phantom: We used Hoffman 3D Brain Phantom with $^{99m}Tc$. We obtained images by LEAP and LEHR collimators (diamox image) and after 6 hours (the half life of $^{99m}Tc$: 6 hours), we use obtained second image (basal image) by same method. Also, we acquired SNR and ratio of white matters/gray matters of each basal image and subtracted image. (2) The evaluation of patient's image: We quantitatively analyzed patients who were examined by LEAP collimators then was classified as a normal group and who were examined by LEHR collimators then was classified as a normal group from 2008. 05 to 2009. 01. We evaluate the results from phantom by substituting factors. We used one-day protocol and injected $^{99m}Tc$-ECD 925 MBq at both basal image acquisition and diamox image acquisition. Results: (1) The evaluation of phantom: After measuring counts from each detector, at basal image 41~46 kcount, stress image 79~90 kcount, subtraction image 40~47 kcount were detected. LEAP was about 102~113 kcount at basal image, 188~210 kcount at stress image and 94~103 at subtraction image kcount were detected. The SNR of LEHR subtraction image was decreased than LEHR basal image about 37%, the SNR of LEAP subtraction image was decreased than LEAP basal image about 17%. The ratio of gray matter versus white matter is 2.2:1 at LEHR basal image and 1.9:1 at subtraction, and at LEAP basal image was 2.4:1 and subtraction image was 2:1. (2) The evaluation of patient's image: the counts acquired by LEHR collimators are about 40~60 kcounts at basal image, and 80~100 kcount at stress image. It was proper to set FWHM as 7 mm at basal and stress image and 11mm at subtraction image. LEAP was about 80~100 kcount at basal image and 180~200 kcount at stress image. LEAP images could reduce blurring by setting FWHM as 5 mm at basal and stress images and 7 mm at subtraction image. At basal and stress image, LEHR image was superior than LEAP image. But in case of subtraction image like a phantom experiment, it showed rough image because SNR of LEHR image was decreased. On the other hand, in case of subtraction LEAP image was better than LEHR image in SNR and sensitivity. In all LEHR and LEAP collimator images, proper subset and iteration frequency was 8 times. Conclusions: We could archive more clear and high SNR subtraction image by using proper filter with LEAP collimator. In case of applying one day protocol and reconstructing by Flash 3D, we could consider application of LEAP collimator to acquire better subtraction image.

• Korea Petroleum Association Journal
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• no.6 s.4
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• pp.4-5
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• 1981

석유절약이나 대체에너지 도입이 진전될수록 석유산업은 과당경쟁에 휘말려 경영체질이 약화되는데 실제로 10%의 추가감산을 단행하느냐의 여부가 문제로서, 산유국의 「분식감산」에 놀아나지 않아야 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.2
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• pp.241-251
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• 2015

In public-key cryptographic system based on finite field arithmetic, it is very important to challenge for implementing high speed operation. In this paper, we focused on 8-bit ATmega128 processor and concentrated on enhancing efficiency of reduction operation which uses irreducible polynomial $f(x)=x^{271}+x^{207}+x^{175}+x^{111}+1$ and $f(x)=x^{193}+x^{145}+x^{129}+x^{113}+1$. We propose optimized reduction algorithms which are designed to reduce repeated memory accesses by calculating final reduced values of Fast reduction. There are 53%, 55% improvement when proposed algorithm is implemented using assembly language, compare to previous Fast reduction algorithm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.82-90
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• 2011

A novel class AB current subtracter(CS) and its application to Norton amplifier(NA) for low-power current-mode signal processing are designed. The CS is composed of a translinear cell, two current mirrors, and two common-emitter(CB) amplifiers. The principle of the current subtraction is that the difference of two input current applied translinear cell get from the current mirror, and then the current amplify through CB amplifier with ${\beta}$ times. The NA is consisted of the CS and wideband voltage buffer. The simulation results show that the CS has current input impedance of $20{\Omega}$, current gain of 50, and current input range of $i_{IN1}$ > $i_{IN2}{\geq}4I_B$. The NA has unit gain frequency of 312 MHz, transresistance of 130 dB, and power dissipation of 4mW at ${\pm}2.5V$ supply voltage.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.443-451
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• 2017

Mammography is commonly used for screening early breast cancer. However, mammographic images, which depend on the physical properties of breast components, are limited to provide information about whether a lesion is malignant or benign. Although a dual-energy subtraction technique decomposes a certain material from a mixture, it increases radiation dose and degrades the accuracy of material decomposition. In this study, we simulated a breast phantom using attenuation characteristics, and we proposed a technique to enable the accurate material decomposition by applying weighting factors for the dual-energy mammography based on a photon-counting detector using a Monte Carlo simulation tool. We also evaluated the contrast and noise of simulated breast images for validating the proposed technique. As a result, the contrast for a malignant tumor in the dual-energy weighted subtraction technique was 0.98 and 1.06 times similar than those in the general mammography and dual-energy subtraction techniques, respectively. However the contrast between malignant and benign tumors dramatically increased 13.54 times due to the low contrast of a benign tumor. Therefore, the proposed technique can increase the material decomposition accuracy for malignant tumor and improve the diagnostic accuracy of mammography.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.439-451
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• 2021

We propose a deep learning-based beamformer combined with spectral subtraction for continuous speech recognition operating in noisy environments. Conventional beamforming systems were mostly evaluated by using pre-segmented audio signals which were typically generated by mixing speech and noise continuously on a computer. However, since speech utterances are sparsely uttered along the time axis in real environments, conventional beamforming systems degrade in case when noise-only signals without speech are input. To alleviate this drawback, we combine online beamforming algorithm and spectral subtraction. We construct a Continuous Speech Enhancement (CSE) evaluation set to evaluate the online beamforming algorithm in noisy environments. The evaluation set is built by mixing sparsely-occurring speech utterances of the CHiME3 evaluation set and continuously-played CHiME3 background noise and background music of MUSDB. Using a Kaldi-based toolkit and Google web speech recognizer as a speech recognition back-end, we confirm that the proposed online beamforming algorithm with spectral subtraction shows better performance than the baseline online algorithm.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.6
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• pp.32-38
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• 2003

An excess-3 code adde $r_tracter circuit is proposed for human friendly decimal computation. Carry lookahead (CLA) circuitry can be used to enhance decimal computation speed. The proposed excess-3 adde $r_tracter employs improved CLA and compensation circuitry recoding computation delay. The circuitry used for addition is used for subtraction without further modification. Substantial speed improvement is obtained compared to conventional designs.signs.

• The Korean Journal of Nuclear Medicine
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• v.32 no.1
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• pp.20-31
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• 1998

A robust algorithm to disclose and display the difference of ictal and interictal perfusion may facilitate the detection of ictal hyperfusion foci. Diagnostic performance of localizing epileptogenic zones with subtracted SPECT images was compared with the visual diagnosis using ictal and interictal SPECT, MR, or PET. Ietal and interictal Tc-99m-HMPAO cerebral perfusion SPECT images of 48 patients(pts) were processed to get parametric subtracted images. Epileptogenic foci of all pts were diagnosed by seizure free state after resection of epileptogenic zones. In subtraction SPECT, we used normalized difference ratio of pixel counts(ictal-interictal)/interictal ${\times}100%$) after correcting coordinates of ictal and interictal SPECT in semi-automatized 3-dimensional fashion. We found epileptogenic zones in subtraction SPECT and compared the performance with visual diagnosis of ictal and interictal SPECT, MR and PET using post-surgical diagnosis as gold standard. The concordance of subtraction SPECT and ictal-interictal SPECT was moderately good(kappa=0.49). The sensitivity of ictal-interictal SPECT was 73% and that of subtraction SPECT 58%. Positive predictive value of ictal-interictal SPECT was 76% and that of subtraction SPECT was 64%. There was no statistical difference between sensitivity or positive predictive values of subtraction SPECT and ictal-interictal SPECT, MR or PET. Such was also the case when we divided patients into temporal lobe epilepsy and neocortical epilepsy. We conclude that subtraction SPECT we produced had equivalent diagnostic performance compared with ictal-interictal SPECT in localizing epileptogenic zones. Additional value of these subtraction SPECT in clinical interpretation of ictal and interictal SPECT should be further evaluated.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1978.04a
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• pp.96.1-96
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• 1978

미생물학적 감산현상에 의하여 과실주중의 산미를 조절하기 위한 방법으로 효모에 의하여 사과산을 알코올로 분해하는 Maloalcohol 발효를 유도하고자 하여 본 연구를 하였다. 이미 발표된 Schizosaccharomyces pombe 0-77보다 단 시간에 강력히 사과산을 소비하는 효모균을 딸기의 과피로부터 분리, 동정하였다. 본 분리균을 J. Lodder의 “The Yeasts”에 준하여 동정한 바 분열법에 의하여 증식하며 포자를 형성하고 galactose 를 발효못하므로 Schizosacoha-romyces 속으로 분류하였다. 위균사를 잘 형성하며 melibiose를 발효하므로 Schizosaccharomyces japonicus와 일치 하였다. 그러나 변종의 동정은 어려우나 위균사의 형태로 보아 Schizosaccharomyces japonicus var. japonicus로 동정하였다.