• 대한의용생체공학회:의공학회지
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• 제34권1호
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• pp.24-33
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• 2013

To enhance the speech perception of hearing aid users in noisy environment, most hearing aid devices adopt various beamforming algorithms such as the first-order differential microphone (DM1) and the two-stage directional microphone (DM2) algorithms that maintain sounds from the direction of the interlocutor and reduce the ambient sounds from the other directions. However, these conventional algorithms represent poor directionality ability in low frequency area. Therefore, to enhance the speech perception of hearing aid uses in low frequency range, our group had suggested a fractional delay subtraction and integration (FDSI) algorithm and estimated its theoretical performance using computer simulation in previous article. In this study, we performed a KEMAR test in non-reverberant room that compares the performance of DM1, DM2, broadband beamforming (BBF), and proposed FDSI algorithms using several objective indices such as a signal-to-noise ratio (SNR) improvement, a segmental SNR (seg-SNR) improvement, a perceptual evaluation of speech quality (PESQ), and an Itakura-Saito measure (IS). Experimental results showed that the performance of the FDSI algorithm was -3.26-7.16 dB in SNR improvement, -1.94-5.41 dB in segSNR improvement, 1.49-2.79 in PESQ, and 0.79-3.59 in IS, which demonstrated that the FDSI algorithm showed the highest improvement of SNR and segSNR, and the lowest IS. We believe that the proposed FDSI algorithm has a potential as a beamformer for digital hearing aid devices.

• 대한전자공학회논문지SD
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• 제48권12호
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• pp.66-72
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• 2011

일본에서의 지상파 DMB 방송 시스템의 송신방식으로 지정된 ISDB-T 스펙은 주파수를 몇 개의 부분(Segment)으로 나누어 고정형 HD-TV 방송과 휴대형 이동 단말기를 동시에 지원할 수 있다. 본 논문은 이중에서 휴대형 이동 단말기의 지원 방식인 원세그(One-Seg) 시스템에 따라 3.5인치 모바일 TV를 개발하고 그 결과를 정리하여 보였다. 추가적으로, 원세그 시스템이 가지는 문제점으로 지적되는 이동 중의 끊김 현상을 보완하기 위하여 2가지 다이버시티 기법을 도입한다. 신뢰성 있는 수신을 위해 2개의 송신 안테나를 활용하는 시공간 다이버시티(Space Time Diversity)와 인접한 다른 단말기와의 정보교환을 통한 협력 수신 다이버시티 (Cooperative Reception Diversity)를 도입 하였고 기존대비 수신 성능의 향상이 있음을 컴퓨터 모의실험을 통해서 보인다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권1호
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• pp.8-22
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• 2014

In the past few decades, CMOS logic technologies and devices have been successfully developed with the steady miniaturization of the feature size. At the sub-30-nm CMOS technology nodes, one of the main hurdles for continuously and successfully scaling down CMOS devices is the parametric failure caused by random variations such as line edge roughness (LER), random dopant fluctuation (RDF), and work-function variation (WFV). The characteristics of each random variation source and its effect on advanced device structures such as multigate and ultra-thin-body devices (vs. conventional planar bulk MOSFET) are discussed in detail. Further, suggested are suppression methods for the LER-, RDF-, and WFV-induced threshold voltage (VTH) variations in advanced CMOS logic technologies including the double-patterning and double-etching (2P2E) technique and in advanced device structures including the fully depleted silicon-on-insulator (FD-SOI) MOSFET and FinFET/tri-gate MOSFET at the sub-30-nm nodes. The segmented-channel MOSFET (SegFET) and junctionless transistor (JLT) that can suppress the random variations and the SegFET-/JLT-based static random access memory (SRAM) cell that enhance the read and write margins at a time, though generally with a trade-off between the read and the write margins, are introduced.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.24.2-24.2
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• 2009

Nanostuctures such as nanodot and nanowire have been extensively studied as building blocks for nanoscale devices. However, the direct growth of the nanostuctures at the desired position is one of the most important requirements for realization of the practical devices with high integrity. Self-assembled nanotemplate is one of viable methods to produce highly-ordered nanostructures because it exhibits the highly ordered nanometer-sized pattern without resorting to lithography techniques. And selective epitaxial growth (SEG) can be a proper method for nanostructure fabrication because selective growth on the patterned openings obtained from nanotemplate can be a proper direction to achieve high level of control and reproducibility of nanostructucture fabrication. Especially, SiGe has led to the development of semiconductor devices in which the band structure is varied by the composition and strain distribution, and nanostructures of SiGe has represented new class of devices such nanowire metal-oxide-semiconductor field-effect transistors and photovoltaics. So, in this study, various shaped SiGe nanostructures were selectively grown on Si substrate through ultrahigh vacuum chemical vapor deposition (UHV-CVD) of SiGe on the hexagonally arranged Si openings obtained using nanotemplates. We adopted two types of nanotemplates in this study; anodic aluminum oxide (AAO) and diblock copolymer of PS-b-PMMA. Well ordered and various shaped nanostructure of SiGe, nanodots and nanowire, were fabricated on Si openings by combining SEG of SiGe to self-assembled nanotemplates. Nanostructure fabrication method adopted in this study will open up the easy way to produce the integrated nanoelectronic device arrays using the well ordered nano-building blocks obtained from the combination of SEG and self-assembled nanotemplates.

• Journal of Radiation Protection and Research
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• 제46권2호
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• pp.48-57
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• 2021

Background: In this study, the complexities of step-and-shoot intensity-modulated radiation therapy (IMRT) plans in magnetic resonance-guided radiation therapy systems were evaluated. Materials and Methods: Overall, 194 verification plans from the abdomen, prostate, and breast sites were collected using a ⁶⁰Co-based ViewRay radiotherapy system (ViewRay Inc., Cleveland, OH, USA). Various plan complexity metrics (PCMs) were calculated for each verification plan, including the modulation complexity score (MCS), plan-averaged beam area (PA), plan-averaged beam irregularity, plan-averaged edge (PE), plan-averaged beam modulation, number of segments, average area among all segments (AA/Seg), and total beam-on time (TBT). The plan deliverability was quantified in terms of gamma passing rates (GPRs) with a 1 mm/2% criterion, and the Pearson correlation coefficients between GPRs and various PCMs were analyzed. Results and Discussion: For the abdomen, prostate, and breast groups, the average GPRs with the 1 mm/2% criterion were 77.8 ± 6.0%, 79.8 ± 4.9%, and 84.7 ± 7.3%; PCMs were 0.263, 0.271, and 0.386; PAs were 15.001, 18.779, and 35.683; PEs were 1.575, 1.444, and 1.028; AA/Segs were 15.37, 19.89, and 36.64; and TBTs were 18.86, 19.33, and 5.91 minutes, respectively. The various PCMs, i.e., MCS, PA, PE, AA/Seg, and TBT, showed statistically significant Pearson correlation coefficients of 0.416, 0.627, -0.541, 0.635, and -0.397, respectively, with GPRs. Conclusion: The area-related metrics exhibited strong correlations with GPRs. Moreover, the AA/Seg metric can be used to estimate the IMRT plan accuracy without beam delivery in the ⁶⁰Co-based ViewRay radiotherapy system.

• 대한토목학회논문집
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• 제41권3호
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• pp.317-325
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• 2021

1988년 부산에서 처음 발병된 소나무재선충병(Pine Wilt Disease, PWD)은 우리나라 소나무에 막대한 피해를 주고 있는 심각한 질병이다. 정부에서는 2005년 소나무재선충병 방제특별법을 제정하고 피해지역의 소나무 이동 금지와 방제를 시행하고 있다. 하지만, 기존의 예찰 및 방제방법은 산악지형에서 동시다발적이고 급진적으로 발생하는 소나무재선충병을 줄이기에는 물리적, 경제적 어려움이 있다. 따라서 본 연구에서는 소나무재선충병 감염의심목을 효율적으로 탐지하기 위해 무인항공기를 이용한 영상자료를 바탕으로 딥러닝 객체인식 예찰 방법의 활용가능성을 제시하고자 한다. 소나무재선충병 피해목을 관측하기 위해서 항공촬영을 통해 영상 데이터를 획득하고 정사영상을 제작하였다. 그 결과 198개의 피해목이 확인되었으며, 이를 검증하기 위해서 접근이 불가한 급경사지나 절벽과 같은 곳을 제외하고 현장 조사를 진행하여 84개의 피해목을 확인할 수 있었다. 검증된 데이터를 가지고 분할방법인 SegNet과 검출방법인 YOLOv2를 이용하여 분석한 결과 성능은 각각 0.57, 0.77로 나타났다.

• 한국전문물리치료학회지
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• 제29권1호
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• pp.54-63
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• 2022

Background: Low back and neck pain are two of the most common medical problems in the adult population. It is estimated that between 70% and 80% adults experience an episode of low back pain at least once during their lifetime. Objects: This study aimed to compare the effects of various stretching exercises and muscle energy techniques used for treatment of iliopsoas, quadratus lumborum, and hamstrings of patients with low back pain. Methods: A total of 52 subjects were randomly assigned to the control group (n = 17), the muscle energy technology group (METG, n = 19), and the stretching exercise group (SEG, n = 16). Interventions were performed twice a week for 4 weeks. Outcomes were measured before and after 4 weeks of treatment in the three groups, using the Korean version of the Oswestry Disability Index, the Visual Analogue Scale (VAS), the Fear Avoidance Belief Questionnaire (FABQ), the Finger to Floor test (FTF), the Modified-Modified Schober Test (MMS), and the Trunk Flexion Range of Motion test. Results: This study showed significant reduction in the pre-test and post-test KODI, VAS, and FABQ scores in all the three groups (p < 0.05). The KODI, VAS, FABQ and FTF assessed in this study showed interactions between the groups and the measurement time point (p < 0.01). After intervention, the KODI, VAS, FABQ and FTF in the SEG and METG were significantly higher (p < 0.05), and there was no difference between the METG and SEG. MMS and HFROM test showed no difference between the three groups (p > 0.05). Conclusion: KODI, VAS, FABQ and FTF showed significant improvement after basic physical therapy, muscle energy technique, and stretching exercise intervention. And there was no significant difference in the intervention effect between the muscle energy group and the stretching exercise group.

• 대한의용생체공학회:의공학회지
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• 제44권2호
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• pp.125-138
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• 2023

The development of AI systems for radiation therapy is important to improve the accuracy, effectiveness, and safety of cancer treatment. The current system has the disadvantage of monitoring patients using CCTV, which can cause errors and mistakes in the treatment process, which can lead to misalignment of radiation. Developed the PMRP system, an AI automation system that uses depth cameras to measure patient's fine movements, segment patient's body into parts, align Z values of depth cameras with Z values, and transmit measured feedback to positioning devices in real time, monitoring errors and treatments. The need for such a system began because the CCTV visual monitoring system could not detect fine movements, Z-direction movements, and body part movements, hindering improvement of radiation therapy performance and increasing the risk of side effects in normal tissues. This study could provide the development of a field of radiotherapy that lags in many parts of the world, along with the economic and social importance of developing an independent platform for radiotherapy devices. This study verified its effectiveness and efficiency with data through phantom experiments, and future studies aim to help improve treatment performance by improving the posture correction mechanism and correcting left and right up and down movements in real time.

• 대한방사선치료학회지
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• 제13권1호
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• pp.91-103
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• 2001

골수이식 수술을 위해 10MV X-ray로 전신 방사선 치료 환자 중 18명을 무작위 추출하여 조사한 후 25일간 말초혈액의(백혈구, Seg. neutrophil, 임파구, 적혈구, 헤모글로빈, 헤마토치, GOT, GPT 등) 수치변화를 대조군 32명과 본인의 방사선 조사전과 비교하여, 고선량의 방사선 피폭이 인체의 말초혈액에 미치는 영향을 평가하였다. 말초혈액 변화 중 백혈구는 방사선 치료 전 검사 $2.51{\times}103{\pm}1.29{\times}103/mm^3$에 비해 $0.22{\times}103{\pm}0.19{\times}103/mm^3$로 최저 $8.63\%$을 나타냈고, 대조군 $7.17{\times}103/mm^3{\pm}1.46{\times}103/mm^3$에 비해서는 $6.35\%$로 낮은 수준을 나타내어 통계적인 유의성이 있었다(P<0.01, r2=0.9151). 백혈구 형태학적 검사 중 Seg. neutrophil은 조사 전 $69.00{\pm}25.60\%$에 비해 $14.17{\pm}21.60\%$로 최저 $20.53\%$수준으로 낮았고, 대조군 $58.09{\pm}7.62\%$에 비해서는 $24.39\%$ 수준으로 감소하였다(P<0.05, r2=0.6316). 임파구 수는 조사 전 $20.29408{\pm}21.15\%$에서 $79.91{\pm}27.30\%$로 최고 3.94배로 높게 나타났고, 대조군 $33.46{\pm}6.79\%$에 비해 2.39배 높게 나타났다(P<0.05, r2=0.7337). 적혈구 수의 변화는 조사 전 $3.18{\times}106{\pm}0.41{\times}106/mm^3$과 대조군 $4.66{\times}106{\pm}0.43{\times}106/mm^3$에 대해 낮은 수준을 나타냈으나 통계적인 유의성은 없었다(P>0.05). 헤모글로빈과 헤마토치의 수치도 조사전과 대조군에 대한 비교에서도 낮게 나타났으나, 모두 통계적인 유의성은 없었다. 그러나 조직학적 검사인 GOT와 GPT값은 조사전과 대조군에 비해 모두 통계적인 유의성이 있었다(P<0.05). 이와 같이 고선량의 방사선 전신 조사 후 말초 혈액 중 백혈구의 수치가 일정 기간에 급격 히 감소하였고, 백혈구 형태학적 검사중 Seg. neutriphil과 임파구수치도 현저하게 감소하였다. 따라서 본 연구 결과로 인체에 고선량의 방사선에 피폭되었을 때, 일반적인 말초혈액 검사를 이용하여 방사선 급성장해 유발 가능자를 1차 적으로 선별 할 수 있는 지표 개발 가능성을 제시하였다고 사료된다.

• 한국미생물·생명공학회지
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• 제33권3호
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• pp.207-214
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• 2005

본 연구에서는 임상에서 분리한 MRSA 균주(n=49)를 대상으로 이 균의 병원성과 관계가 있는 것으로 알려진 유전자들을 선정하여 PCR 방법을 이용하여 이들 유전자들의 보유 유무를 결정하였다. 이들 MRSA 균주는 모두 coa 유전자를 보유하고 있었고, 또한 이들 유전자는 500bp($6{\%}$), 580bp($27{\%}$), 660bp($65{\%}$) 및 740bp($2{\%}$)로 4가지 종류의 polymorphism이 검출되었다. Hemolysin 유전자의 경우 4-5종 이상 다른 locus들을 보유하였고, 그 중 25개 균주($51{\%}$)가 hla / hlb / hld / hlg / hig-2 유전자를 모두 보유하였으며, 가장 많은 분포를 나타내었다. 한편, MRSA 균주는 다양한 enterotoxin 유전자의 조합을 보였으며, sea와 seb 유전자의 경우 모든 49개 균주에서 보유하고 있었다. 그러나 sei 유전자는 31균주($63{\%}$), tsst-1 유전자는 16균주($33{\%}$), seg 유전자는 14균주($29{\%}$), sec 유전자는 8균주($16{\%}$), seh 유전자는 5균주($10{\%}$), sed 유전자와 sej 유전자는 1균주($2{\%}$)에서 각각 검출되었다. 그러나 see 유전자 및 eta와 etb유전자는 어떤 분리균주에서도 검출되지 않았다. 또한 sea / seb 유전자 조합이 11개 균주($23{\%}$)로부터, sea / seb / sei 유전자 조합은 9개 균주($19{\%}$)로부터, sea / seb / seg / sei /tsst-1 유전자 조합은 5개 균주($10{\%}$)로부터 각각 검출되었다. 그리고 다른 유전자의 조합은 $10{\%}$이하로 검출되었다.