• 교육시설 논문지
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• 제25권6호
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• pp.3-10
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• 2018

This study analyzes the average acquisition ratio between the 1st and 4th grade and the distribution and characteristics of the acquisition between the assessment items based on the case of Green Building Certification System(GBCS) for the educational facilities on the university campus. By evaluating the difference between the best scored grade (Green 1st Grade) and the general grade (Green 4th Grade), we classified the cases where the difference between grades with little or big difference. By doing this, we were able to analyze the trend that were difficult to distinguish between difficult to score and an easy task. G-SEED should be used not only as a formal system for certifying certification, but also to provide environmentally-friendly technology for buildings as well as meeting market needs. To do this, it is necessary to further refine the evaluation criteria. In addition, it is necessary to establish a qualitative evaluation system by providing detailed criteria for items that are not distinguishable among grades. It is expected that this study will be used to improve the detailed evaluation items by analyzing trends in the average acquisition rate presented in this study.

• Current Optics and Photonics
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• 제7권6호
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• pp.683-691
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• 2023

A typical terahertz time-domain spectroscopy system requires large, expensive, and heavy hardware such as a lock-in amplifier and a function generator. In this study, we replaced the lock-in amplifier and the function generator with a single sound card built into a typical desktop computer to significantly reduce the system size, weight, and cost. The sound card serves two purposes: 1 kHz chopping signal generation and raw data acquisition. A unique software lock-in (Python coding program to eliminate noise from raw data) method was developed and successfully extracted THz time-domain signals with a signal-to-noise ratio of ~40,000 (the intensity ratio between the peak and average noise levels). The built-in sound card with the software lock-in method exhibited sufficiently good performance compared with the hardware-based method.

• 핵의학기술
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• 제19권1호
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• pp.67-71
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• 2015

Purpose At recently, we enter into the aging society and a age-related disease is increasing. Among that, prevalence of degenerative brain disease like Parkin's disease will be increased. So, many radiopharmaceuticals is developed to diagnosis early and to evaluate the performance of therapeutic drugs. Especially $^{18}F-DOPA$ which involved at dopamine synthesis and function of storage is widely used to the diagnosis of Parkinson's disease as well as brain tumors. in the study, we will evaluate the distribution pattern of $^{18}F-DOPA$ at the striatum by using dynamic study. Materials and Methods We used Biograph Truepoint(Siemens, Germany) as PET/CT scanner, injected a $^{18}F-DOPA$ ($600{\pm}30MBq$) to patient (4men, 6women. $67{\pm}11age$) who visited our hospital from June to September, started 95min dynamic study at same time. after finishing acquisition, we reconstructed PET data with 19 frame every 5 minutes, analysed a average counts at ROI's where set at both striatums, anterior putamen, posterior putamen Results Counts in the cerebellum as the background formed a plateau after 90 minutes from the highest out rapidly reduced to 15 minutes. Counts of anterior putamen and posterior gradually increased but formed a plateau after 60min. A count ratio of Striatum to cerebellum was continuously increased up to more than 95 minutes, A count ratios of an anterior putamen to posterior one formed a plateau after 85 minutes. Conclusion The dynamic acquisition can be possible to evaluate a distribution of the $^{18}F-DOPA$ in the striatum and the VOI analysis through a dynamic acquisition and a variety of patterns. Futhermore, to make a uniformed distribution and count ratio of striatum to cerebellum, a static acquisition will have to start 90minutes later after injection.

• 한국통신학회논문지
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• 제25권5B호
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• pp.871-878
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• 2000

이 논문은 저궤도 이동 위성 통신에서 나타나는 심각한 도플러 천이와 페이딩을 극복하면서 패킷 전송효율을 증가시킬 수 있는 DS/CDMA 시스템의 초기동기기법으로 분할 정합 여파기/참조 여파기 기법을 제안한다. 정합여파기의 정합구간을 분할하는 분할 정합여파기를 이용하여 극심한 도플러 천이를 극복하였으며, 참조여파기를 이용하여 시변하는 간섭과 페이딩에 강인한 초기동기를 이룰 수 있다. 성능분석의 척도로써 평균초기동기시간과 패킷 전송효율을 이용하며, 도플러 천이와 칩당 에너지대 잡음비, 사용자 이동속도, 음영 표준편차, 패킷 프리앰블내 심볼수 등과의 관계를 고찰한다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.222-228
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• 2023

This study aimed to analyze the applicability of the improved median filter in positron emission tomography (PET)/magnetic resonance (MR) fusion images based on parallel imaging using generalized autocalibrating partially parallel acquisition (GRAPPA). In this study, a PET/MR fusion imaging system based on a 3.0T magnetic field and ¹⁸F radioisotope were used. An improved median filter that can set a mask of the median value more efficiently than before was modeled and applied to the acquired image. As quantitative evaluation parameters of the noise level, the contrast to noise ratio (CNR) and coefficient of variation (COV) were calculated. Additionally, no-reference-based evaluation parameters were used to analyze the overall image quality. We confirmed that the CNR and COV values of the PET/MR fusion images to which the improved median filter was applied improved by approximately 3.32 and 2.19 times on average, respectively, compared to the noisy image. In addition, the no-reference-based evaluation results showed a similar trend for the noise-level results. In conclusion, we demonstrated that it can be supplemented by using an improved median filter, which suggests the problem of image quality degradation of PET/MR fusion images that shortens scan time using GRAPPA.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권10호
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• pp.733-740
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• 2004

In this paper, an improved algorithm for the extraction of respiration signal from the electrocardiogram (ECG) is proposed. The whole system consists of two-lead electrocardiogram acquisition (lead Ⅰ and Ⅱ), baseline fluctuation elimination, R-wave detection, adjustment of sudden change in R-wave area using moving average, and optimal lead selection. In order to solve the problem of previous algorithms for the ECG-derived respiration (EDR) signal acquisition, we proposed a method for the optimal lead selection. An optimal EDR signal among the three EDR signals derived from each lead (and arctangent of their ratio) is selected by estimating the instantaneous frequency using the Hilbert transform, and then choosing the signal with minimum variation of the instantaneous frequency. The proposed algorithm was tested on 15 subjects, and we could obtain satisfactory respiration signals that shows high correlation (r>0.9) with the signal acquired from the chest-belt respiration sensor.

• 아태비즈니스연구
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• 제12권1호
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• pp.135-149
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• 2021

Purpose - I analyzes risk-to-performance evaluated in the market using data from sale and lease back. Specifically, I analyze from the perspective of financial institutions that purchase sale and lease back based on the cases of investment by ship investment companies and acquisition of ships. Design/methodology/approach - I use 49 sale and lease back data from 2017 to 2019 for empirical analysis. Findings - The main results of this paper are as follows. First, after sale and lease back of domestic ships, the average amount of sales by the leased shipping company is 25.1 billion won, the average amount of investment by the purchased financial institution is 14.6 billion won (60%) and the average length of the ship is nine years. In ship finance, sale and lease back is deemed to be appropriately used as a means of restructuring for a large amount of money. Second, the main risk factor for sale and lease back of domestic ships is credit risk and can be measured in VaR in practice. As a result of the empirical analysis, the average credit risk burden ratio is 9%. As a major risk factor, low creditworthiness of restructuring companies is the key. Third, as a result of measuring the profitability of financial institutions that purchase sale and lease back of domestic ships at a net current price, it has an average value of 300 million won, but the deviation by case is very large. Fourth, the risk adjusted performance of sale and lease back of domestic ships is 0.54 on average compared to the total risk capital, and 0.52 compared to the stock-risk capital, and as with profitability earlier, the deviation of each case is very large and misaligned. In order to boost the sale and lease back market for large and long-term assets, in order to overcome low profitability as a prerequisite for future participation of commercial purchased financial institutions, it is expected that purchase decisions based on expectations versus risk will be necessary. Research implications or Originality - The results of this paper are expected to broaden the understanding of sale and lease back and foster the ability to assess long-term risk and performance. Based on this, it is believed that rapid restructuring of companies through sale and lease back of large amounts of long-term assets will greatly increase the utility of the domestic financial market.

• 핵의학기술
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• 제16권2호
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• pp.18-24
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• 2012

Lung SPECT는 planar scan 보다 깊이 위치한 병변을 명확히 보여주며 보다 예민한 것으로 보고되고 있다. 그러나 ventilation SPECT는 정맥주사를 통해 방사성의약품을 주입하는 perfusion SPECT와 다르게 환자의 호흡을 통해 흡입시키므로, 원활한 호흡이 불가능한 환자의 경우 목적 장기에 방사성의약품의 섭취율이 저하되고 검사에 유효한 적정count/rate가 낮아지므로 필연적으로 검사시간이 길어지게 되어 이에 수반되는 여러 문제로 인하여 실제 임상에 적용하기 어려운 실정이다. 따라서 본 연구는 고감도(high sensitivity) 특성을 지닌 AP (All Purpose) 혹은 GP (General Purpose) collimator를 사용하여 low count/rate 환자의 검사시간을 단축시킴으로써 lung ventilation SPECT 임상적용 가능성과 유용성을 평가하였다. 정상 성인 남녀 4명($24.3{\pm}0.95$세)을 실험대상으로 Technegas 370 MBq을 흡입시키고, E.cam SPECT를 사용하여 count/rate를 측정한 후, LEUHR, LEHR, LEAP collimator를 장착하여 300counts acquisition 조건으로 ANT, POST, LPO, RPO, both-LAT 총 6 view의 lung ventilation planar scan 하였다. 동일 실험 대상자를 본원에서 사용하던 기존 프로토콜을 적용하여 70 kcounts/view acquisition 조건으로 high counting mode SPECT를 시행하고, 같은 방법으로 7kcounts/view acquisition하여 비교 실험인 low counting mode SPECT를 시행한 후 모든 실험의 결과를 lung segmentation ratio와 검사 소요시간을 통해 비교하여 분석하였다. 각 실험군 사이의 상관관계를 분석하기 위해 paired t-test를 시행하였고, p값이 0.05를 초과할 때 실험의 통계적 의미가 있는 것으로 판단하였다. 모든 자료의 통계처리는 SPSS ver. 20을 사용하였으며, 각 실험 결과는 산술 및 기하 평균(mean)을 구하고${\pm}$표준편차(SD)를 산출하였다. 실험 결과 lung planar scan은 300 kcounts/6 iew를 acquisition하여 총 1,800 kcounts를 획득하였다. 반면 7 kcounts/view로 acquisition한 low counting mode SPECT의 경우 collimator 종류에 따라서 최소 773 kcounts에서 최대 1,106 kcounts를 획득하였고, 70 kcounts/view로 acquisition한 high counting mode SPECT의 경우 collimator 종류에 따라서 최소 7,984 kcounts에서 최대 10,222kcounts를 획득하였다. 모든 실험 자료를 통해 실험대상 4명의 lung segmentation ratio를 산출하고, 평균값과 표준편차를 계산한 결과, LT:RT lung ratio는 순서대로 각각 45.5:54.5 (${\pm}0.26$), 45.4:54.6 (${\pm}0.40$), 50.1:49.9 (${\pm}0.28$), 49.4:50.6 (${\pm}0.57$)이었다. 따라서 정량분석한 결과 planar scan과 low, high counting mode SPECT사이 collimator 종류에 의한 lung segmentation ratio는 오차 범위내에 모두 존재하였다. 보다 자세한 분석을 위해 기존의 LEHR collimator를 장착한 planar scan과 비교 실험인 LEAP collimator를 장착한 low counts mode SPECT를 통계처리한 결과 p-value가 0.10이상으로 두 실험의 결과는 통계적으로 유의하였다. 실험에 소요된 시간을 분석한 결과 planar scan은 LEUHR, LEHR, LEAP collimator 순서로 각각 $1803{\pm}268$ sec, $915{\pm}162$ sec, $501{\pm}134$ sec이었고, 비교실험인 low counting mode SPECT는 $1125.5{\pm}103.6$ sec, $900{\pm}64$ sec, $740{\pm}0$ sec 이었으며, 본원에서 사용하던 기존 프로토콜인 high counting mode SPECT는 $5794.5{\pm}946.5$ sec, $3620{\pm}397.9$ sec, $2020{\pm}104.5$ sec이었다. 관심실험인 LEAP collimator를 장착한low counting mode SPECT의 검사 소요시간 740 sec에 비하여, 기존 본원의 프로토콜인 LEHR collimator를 장착한 high counting mode SPECT의 검사 소요시간 평균은 3620sec이므로, 약 5배 정도 시간 단축이 가능한 것으로 조사되었으며, 모든 실험의 정량분석 결과도 임상적으로 유의한 것으로 분석되었다. 결국 high sensitivity LEAP collimator를 장착하여 lung SPECT를 시행하면, 임상적으로 유의한 정량분석 결과를 얻을 수 있으며, 동시에 검사시간을 효과적으로 단축시킬 수 있음을 의미한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권2호
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• pp.60-64
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• 2001

The degradation process of silicone rubber was investigated by leakage current monitoring in Inclined-Plane method. DAS (Data Acquisition System) with 12-bit, 8-channel A/D converter was prepared. Average current, cumulative charge, current waveform and the number of peak pulses were measured on-line. And, FFT (Fast Fourier Transform) analysis was performed with stored current waveform. Besides, maximum erosion depth was measured in order to use as the indicator of the degradation process. So, the results of leakage current components and maximum erosion depth measurements were compared to find one or more components which have trends of changing similarly to that of erosion process. The result suggests that the ratio of peak current to r.m.s. current, harmonic contents and the number of peak pulses are well corresponding with the degradation process.

• Journal of Positioning, Navigation, and Timing
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• 제8권4호
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• pp.165-173
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• 2019

In this paper, we apply a discrete wavelet packet transform (DWPT) to reduce the influence of interference in global positioning system (GPS) signals and compare the interference mitigation performance of various wavelets. By applying DWPT to the received signal, we can gradually divide the received signal band into low-pass and high-pass bands. After calculating the average power for the separate bands, we can determine whether there is interference by comparing the value with the given threshold. For a band that includes interference, we can reconstruct the whole band signal using inverse DWPT (IDWPT) after applying a nulling method that sets all of the wavelet coefficients to 0. The reconstructed signals are correlated with the pseudorandom noise (PRN) codes to acquire GPS signals. The performance evaluation is based on the number of satellite signals whose peak ratio (defined as the ratio of the first and second correlation peak values in the acquisition stage) exceeds the threshold. In this paper, we compare and evaluate the performance of 6 wavelets including Haar, Daubechies, Symlets, Coiflets, Biorthogonal Splines, and Discrete Meyer.