• 한국소음진동공학회논문집
• /
• 제16권6호
• /
• pp.665-673
• /
• 2006

이 연구는 유전 알고리듬, 타부탐색법 그리고 반응표면법등 최근 많이 사용하고 있는 프로그램들의 장점들을 결합한 새로운 조합 유전 알고리듬을 제안한다. 이 알고리듬은 반응표면법 및 심플렉스법을 사용하여 유전알고리듬의 약점으로 여겨지는 수렴속도를 항상 시키도록 하였다. 또한 유전 알고리듬에서 램덤 한 다양성을 제공하지만, 이 연구에서는 타부리스트를 이용하여 체계적인 다양성을 추구하도록 하였다. 그리고 전통적인 시함함수에 본 알고리듬을 적용함으로써 이 방법의 효율성을 입증하였고 그 결과를 유전 알고리듬의 결과와 비교하였다. 또한 새롭게 제안된 알고리듬을 선미부에 위치한 청수탱크의 중량최적화에 적용한 결과 전역 최적해를 효율적으로 찾는 것을 입증하였다. 또한 반응표면법을 사용한 새로운 유전알고리듬의 경우 실제 추가적인 목적함수를 평가하기 위한 계산이 필요 없으므로 수렴속도가 일반 유전 알고리듬보다 향상되었음을 알 수 있었다. 마지막으로 제안된 조합 유전 알고리듬은 전역탐색능력과 수렴속도 측면에서 매우 강력한 전역 최적화 알고리듬임을 알 수 있었다.

• Journal of Korean Neurosurgical Society
• /
• 제60권5호
• /
• pp.577-583
• /
• 2017

Objective : Laminoplasty is an effective surgical method for treating cervical degenerative disease. However, postoperative complications such as kyphosis, restriction of neck motion, and instability are often reported. Despite sufficient preoperative lordosis, this procedure often aggravates the lordotic curve of the cervical spine and straightens cervical alignment. Hence, it is important to examine preoperative risk factors associated with postoperative kyphotic alignment changes. Our study aimed to investigate preoperative radiologic parameters associated with kyphotic deformity post laminoplasty. Methods : We retrospectively reviewed the medical records of 49 patients who underwent open door laminoplasty for cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) at Pusan National University Yangsan Hospital between January 2011 and December 2015. Inclusion criteria were as follows : 1) preoperative diagnosis of OPLL or CSM, 2) no previous history of cervical spinal surgery, cervical trauma, tumor, or infection, 3) minimum of one-year follow-up post laminoplasty with proper radiologic examinations performed in outpatient clinics, and 4) cases showing C7 and T1 vertebral body in the preoperative cervical sagittal plane. The radiologic parameters examined included C2-C7 Cobb angles, T1 slope, C2-C7 sagittal vertical axis (SVA), range of motion (ROM) from C2-C7, segmental instability, and T2 signal change observed on magnetic resonance imaging (MRI). Clinical factors examined included preoperative modified Japanese Orthopedic Association scores, disease classification, duration of symptoms, and the range of operation levels. Results : Mean preoperative sagittal alignment was $13.01^{\circ}$ lordotic; $6.94^{\circ}$ lordotic postoperatively. Percentage of postoperative kyphosis was 80%. Patients were subdivided into two groups according to postoperative Cobb angle change; a control group (n=22) and kyphotic group (n=27). The kyphotic group consisted of patients with more than $5^{\circ}$ kyphotic angle change postoperatively. There were no differences in age, sex, C2-C7 Cobb angle, T1 slope, C2-C7 SVA, ROM from C2-C7, segmental instability, or T2 signal change. Multiple regression analysis revealed T1 slope had a strong relationship with postoperative cervical kyphosis. Likewise, correlation analysis revealed there was a statistical significance between T1 slope and postoperative Cobb angle change (p=0.035), and that there was a statistically significant relationship between T1 slope and C2-C7 SVA (p=0.001). Patients with higher preoperative T1 slope demonstrated loss of lordotic curvature postoperatively. Conclusion : Laminoplasty has a high probability of aggravating sagittal balance of the cervical spine. T1 slope is a good predictor of postoperative kyphotic changes of the cervical spine. Similarly, T1 slope is strongly correlated with C2-C7 SVA.

• 대한의용생체공학회:의공학회지
• /
• 제40권3호
• /
• pp.105-115
• /
• 2019

Brain tumor surgery may be difficult, but it is also incredibly important. The technological improvements for traditional brain tumor surgeries have always been a focus to improve the precision of surgery and release the potential of the technology in this important area of the body. The need for precision during brain tumor surgery has led to an increase in Robotic-assisted surgeries (RAS). One of the challenges to the widespread acceptance of RAS in the neurosurgery is to recognize invisible tumor accurately. Therefore, it is important to detect brain tumor size and location because surgeon tries to remove as much tumor as possible. In this paper, we proposed brain tumor detection procedures for MRI (Magnetic Resonance Imaging) system. A method of automatic brain tumor detection is needed to accurately target the location of the lesion during brain tumor surgery and to report the location and size of the lesion. In the qualitative assessment, the proposed method showed better results than those obtained with other brain tumor detection methods. Comparisons among all assessment criteria indicated that the proposed method was significantly superior to the threshold method with respect to all assessment criteria. The proposed method was effective for detecting brain tumor.

• Fisheries and Aquatic Sciences
• /
• 제24권1호
• /
• pp.19-31
• /
• 2021

Seaweeds are a potential source of minerals, essential amino acids, fatty acids, proteins, and various bioactive compounds such as antioxidants. The higher water content of seaweeds reduces the shelf life and this requires the appropriate drying method. The drying conditions play a major role in the conservation of nutrient composition in dried seaweeds. In recent years, the seaweed industry has used many different drying methods with advantages and limitations. Hybrid hot-water Goodle dryer (HHGD) which is a special dryer mixed with hot-water and a Korean traditional heating system (Goodlejang) might be a solution to avoid these limitations. The present study evaluated the effect of drying conditions in HHGD on nutrient composition and bioactivities of brown seaweeds. Moreover, freeze-dryer (FD) and HHGD were employed in this study to compare the dried outputs obtained from four brown seaweed species. The present study aims to evaluate the effect of the hybrid hot-water Goodle drying method (HHGDM) on the nutritional composition and antioxidant activity of dried seaweeds. AOAC standard methods were used to analyze the proximate composition of dried samples and their 70% ethanol extract. The intracellular and extracellular antioxidant activities were evaluated using Vero cells and electron spin resonance (ESR) spectrometer respectively. High performance liquid chromatography, apoptotic body formation, and in-vivo experiments were used for further confirmation of the quality of dried output. The proximate composition results obtained from drying in HHGD and FD did not exhibit any significant difference. Moreover, the seaweed extracts from the dried seaweeds by HHGD and FD dryings were also not different and both significantly down-regulated in-vivo and in-vitro oxidative stress. Furthermore, the high performance liquid chromatography results revealed that the two dryers did not make the major peaks different in the chromatograms. Freeze-drying method (FDM) provides elevated quality for dried output, but there are limitations such as high cost and low capacity. The results from a novel HHGD did not provide any significant difference with the results in FD and expressed a potential to avoid the limitations in FD. Overall, these findings solidified the applicability of HHGD over FD.

• Journal of Korean Neurosurgical Society
• /
• 제64권1호
• /
• pp.78-87
• /
• 2021

Objective : Intraoperative neurophysiological monitoring (IONM) has been widely used during spine surgery to reduce or prevent neurologic deficits, however, its application to the surgical management for cervical myelopathy remains controversial. This study aimed to assess the success rate of IONM in patients with cervical myelopathy and to investigate the factors associated with successful baseline monitoring and the effect of increasing the stimulation intensity by focusing on motor evoked potentials (MEPs). Methods : The data of 88 patients who underwent surgery for cervical myelopathy with IONM between January 2016 and June 2018 were retrospectively reviewed. The success rate of baseline MEP monitoring at the initial stimulation of 400 V was investigated. In unmonitorable cases, the stimulation intensity was increased to 999 V, and the success rate final MEP monitoring was reinvestigated. In addition, factors related to the success rate of baseline MEP monitoring were investigated using independent t-test, Wilcoxon rank-sum test, chi-squared test, and Fisher's exact probability test for statistical analysis. The factors included age, sex, body mass index, diabetes mellitus, smoking history, symptom duration, Torg-Pavlov ratio, space available for the cord (SAC), cord compression ratio (CCR), intramedullary increased signal intensity (SI) on magnetic resonance imaging, SI length, SI ratio, the Medical Research Council (MRC) grade, the preoperative modified Nurick grade and Japanese Orthopedic Association (JOA) score. Results : The overall success rate for reliable MEP response was 52.3% after increasing the stimulation intensity. No complications were observed to be associated with increased intensity. The factors related to the success rate of final MEP monitoring were found to be SAC (p<0.001), CCR (p<0.001), MRC grade (p<0.001), preoperative modified Nurick grade (p<0.001), and JOA score (p<0.001). The cut-off score for successful MEP monitoring was 5.67 mm for SAC, 47.33% for the CCR, 3 points for MRC grade, 2 points for the modified Nurick grade, and 12 points for the JOA score. Conclusion : Increasing the stimulation intensity could significantly improve the success rate of baseline MEP monitoring for unmonitorable cases at the initial stimulation in cervical myelopathy. In particular, the SAC, CCR, MRC grade, preoperative Nurick grade and JOA score may be considered as the more important related factors associated with the success rate of MEP monitoring. Therefore, the degree of preoperative neurological functional deficits and the presence of spinal cord compression on imaging could be used as new detailed criteria for the application of IONM in patients with cervical myelopathy.

• 한방재활의학과학회지
• /
• 제32권1호
• /
• pp.51-62
• /
• 2022

Objectives Objective of this study is to investigate the role of paraspinal muscles by examining the correlation between slip percentage (SP) of spondylolisthesis and fatty infiltration of lumbar paraspinal muscle. Methods Retrospective analysis was performed on 45 patients diagnosed with spondylolisthesis based on medical records. Using T2-weighted axial magnetic resonance imaging, cross-sectional areas (CSAs) of psoas major (PM), multifidus (MU) and erector spinae (ES) were calculated and divided by CSA of lower level vertebral body (VB). SP was measured using sagittal T2-weighted images. Correlation of SP with muscle relative cross-sectional area (RCSA) and muscle fatty infiltration by Goutallier classification was respectively analyzed using Spearman correlation. Statistic assessment conducted by Wilcoxon signed rank test and paired t-test using program GraphPad prism 5 (GraphPad Software, Inc., San Diego, CA, USA). Results Spondylolisthesis forward slip percentage by Taillard's method was negatively associated with both side MU RCSAs. No significant correlation was found between PM RCSA, ES RCSA and SP. Forward slippage was significantly correlated with fatty infiltration of lumbar paraspinal muscle measured by Goutallier classification. Conclusions This study is to understand the role of paraspinal muscle affecting spinal instability by investigating correlation between statistical deviation of lumbar muscle characters (RCSA, fatty infiltration of lumbar muscle) and SP. We found that spondylolisthesis SP is positively related to fatty infiltration of lumbar paraspinal muscle. and is negatively associated with both side MU RCSAs.

• 한국지반환경공학회 논문집
• /
• 제24권2호
• /
• pp.31-40
• /
• 2023

본 연구는 고밀도 지진 관측망 구축 시 지표 가속도 측정 및 조기경보 활용을 위한 효율적 관측소 설치 방법을 수립하기 위하여 테스트베드에 지표, 1m, 2m, 9m 깊이의 임시관측소를 설치하여 상시 잡음, 인공 가진 신호 및 지진 계측 자료의 깊이별 변화를 분석하였다. 연구대상지의 상시 잡음 분석 결과 1s 이하의 단주기 영역은 주변의 인위적 잡음이 우세하였으며, 1s 이상 장주기 영역은 풍속의 변동과 큰 상관성을 보였다. 2차원 지진계 배열을 통한 상시 잡음 진동수-파수(FK) 분석 결과 단주기 상시 잡음은 표면파 보다는 주로 체적파의 형태로 유입되는 것으로 추정된다. 잡음 수준 분석 결과 9m 이하에서는 낮은 수준의 상시 잡음이 관측되었으나, 지표, 1m, 2m 지진계에서는 토사층의 동적 거동에 의해 T < 0.1s에서 잡음의 증폭이 발생하는 것을 확인하였다. 인공 가진실험 및 괴산지진 계측 자료 분석 결과 전반적으로 깊이가 깊어질수록 신호의 크기가 감소함을 확인하였으며, 스펙트럼비 및 응답스펙트럼 분석 결과 지표와 1m에서 3m 깊이 토사층의 고유진동수에 해당하는 20Hz(T=0.05s) 대역의 지반운동이 크게 증폭되는 것으로 나타났다. 본 연구 결과 상시미동과 가진실험을 통해 대상구간의 관측환경을 조사하여 지진계 설치 방법 및 깊이 선정시 활용할 수 있는 것으로 나타났으며, 향후 다수의 지역에서 다양한 환경을 고려한 연구가 진행된다면 관측소 설치 깊이, 설치방법, 환경 조사방법에 대한 가이드라인을 제시하는데 큰 도움이 될 것으로 기대된다.

• 대한영상의학회지
• /
• 제82권6호
• /
• pp.1413-1440
• /
• 2021

MRI에서 추간판의 이상 신호와 위, 아래 척추체 종판의 파괴, 종판 주변의 골수부종 등은 감염성 척추염의 전형적인 소견으로 여겨지나 퇴행성 척추질환, acute Schmorl's node, 척추관절병증, synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO)/chronic recurrent multifocal osteomyelitis, 척추신경관절병증, calcium pyrophosphate dehydrate 결절침착질환 등 다양한 비감염성 척추질환에서도 나타날 수 있다. MRI에서 이러한 비감염성 척추질환과 감별되는 감염성 척추염의 영상 소견은 추간판의 고신호와 농양, 척추 연부조직의의 농양, 그리고 T1 강조영상에서 저신호로 보이는 종판의 경계가 불명확해지는 점 등이다. 그러나 이러한 감별점이 항상 적용되는 것은 아니며 감염성, 비감염성 질환의 영상 소견에 유사점이 많기 때문에 정확한 진단을 위해서는 감염성 척추염뿐만 아니라 감염과 감별해야 하는 다양한 질환의 병태생리와 연관된 영상학적 특징을 아는 것이 중요하다.

• 스마트미디어저널
• /
• 제13권4호
• /
• pp.114-123
• /
• 2024

본 논문은 착용형 증강현실(Augmented Reality, AR) 기반 체험형 콘텐츠인 AR 돌탑 콘텐츠를 제안한다. 착용할 수 있는 형태의 증강현실이 주목받고 있음에도 불구하고 기술 수용은 산업현장 등 특수한 목적으로의 응용이 집중적으로 개발되고 있는 현황이다. 반면 제안한 AR 돌탑 콘텐츠는 일반 사용자들이 공감하고 쉽게 참여할 수 있도록 '돌탑' 소재를 바탕으로 하고 있으며, 이동 환경에서 공간을 활용하고 자연스러운 손 제스처를 바탕으로 돌을 찾고 쌓을 수 있도록 구성하였다. 제안한 AR 돌탑 콘텐츠는 HoloLens 2 환경에서 구현되었으며 소규모 미술관에서 파일럿 전시를 통해 일반 사용자를 대상으로 평가를 수행하였다. 평가 결과 콘텐츠에 대한 전반적인 만족도는 평균 3.85로 나타났으며, 돌탑 소재에 대한 콘텐츠 적절성은 4.15로 매우 높게 나타났다. 특히, 그중에서도 콘텐츠 이해도와 사운드에 대한 만족도는 높게 나타났으나, 객체인지와 신체 적응도 및 객체 컨트롤에서 다소 낮은 만족도를 보였다. 위와 같은 사용자 평가를 통해 소재에 대한 공감대와 긍정적인 반응을 확인하고, 착용형 AR 환경에서의 체험과 상호작용에서의 일반 사용자의 어려움을 확인하였다.

• 한국의학물리학회지:의학물리
• /
• 제25권3호
• /
• pp.176-184
• /
• 2014

척추뼈전이암 환자를 대상으로 본원의 동시통합추가치료법(SIB)과 RTOG 0631 프로토콜에 따른 체부정위방사선치료계획을 세우고, 선량분포를 비교하였다. 간암 원발인 척추 뼈 전이암 환자 5명을 대상으로 전산화단층촬영 영상과 자기공명영상(T1, T2)를 바탕으로 영상융합을 시행하였다. 본원에서 시행하는 SIB방법은 영상에서 보이는 종양을 GTV로 설정하고, GTV를 포함한 전체 척추체부(entire vertebral body, VB)를 CTV1로 정의하였고 GTV에 18 Gy CTV1에 10 Gy를 1회 처방하였다. RTOG 0631 프로토콜 방법은 GTV의 침윤 정도에 따라 주변부의 추근, 좌우 횡돌기 및 극돌기 등을 선택적으로 포함하여 CTV2로 정의하였고 18 Gy 1회 처방하여 체부정위방사선치료계획을 시행하였다. 선량체적화 결과값을 선량-체적 히스토그램을 통해 분석한 결과, 두 방법 모두 표적에 대하여 처방 선량을 만족하였으며, 척수 및 정상 장기에 대하여는 SIB방법이 RTOG 0631프로토콜보다는 낮은 값을 보였다. 또한, 전체 VB의 조사선량분포를 정량화한 결과, RTOG 0631프로토콜에서도 SIB방법과 동일한 처방선량 허용치 85%이상을 포함하는 것으로 나타났다. 하지만 정상 장기에 대한 선량은 RTOG 0631 프로토콜에 따른 치료 방법이 높은 편이었다. 주변부 장기의 부작용이 우려되는 임상적 상황의 경우 조사 체적이 적은 SIB방법이 좋은 선택이 될 수 있을 것이다. 결론적으로 SIB방법이나 RTOG 0631 프로토콜에 따른 표적체적 설정을 통한 체부정위방사선치료계획 모두 유사한 결과를 보였으며, 향후 다양한 연구를 통해 종양제어확률 및 부작용 확률의 차이를 분석해야 할 것이다.