Median Filter와 Dyadic sorting method를 이용한 DT-MRI Regularization

권순동(Kwon, Soon Dong),우종형,이훈,김태환,권기운,김동윤 한국산업응용수학회 2010 한국산업응용수학회 학술대회 논문집 Vol.5 No.2

자기공명확산텐서영상(Diffusion Tensor Magnetic Resonance Image, DT-MRI)으로부터 얻어진 확산텐서는 확산 타원체로 정의 될 수 있으며, 확산의 비등방성정도와 방향성을 보여주게 된다. 확산이 가장 빠르게 일어나는 방향은 해당 voxel내의 가장 큰 고유값(eigenvalue)에 연결된 고유벡터(eigenvector)의 방향이다. 이러한 PEV(Principle Eigen Vector)는 잡음에 민감하여 정확하지 않은 값을 가질 수 있다. 신경다발추적결과는 이처럼 잡음에 매우 민감한 PEV로부터 얻어지기 때문에 실제 신경다발의 방향에서 벗어날 수 있다. 따라서 잡음을 제거하기 위한 정규화(regularization) 과정이 필요하다. 본 연구에서는 고유값과 고유벡터를 정규화 하기 위한 방법으로 Median Filter과 Dyadic sorting 방법을 사용하였고 이를 구현하기 위한 알고리듬을 제시하였다.

신경회로망 제어기를 이용한 PID 파라미터 추정에 관한 연구

권중동(Jung-Dong Kwon),전기영(Kee-Young Jeon),김은기(Eun-Gi Kim),이승환(Seung-Hwan Lee),오봉환(Bong-Hwan Oh),이훈구(Hoon-Goo Lee),서영수(Young-Soo Seo),한경희(Kyung-Hee Han) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

In this paper, supposed to solve these problem to PID parameters controller algorithm using ANN. In the proposed algorithm, the parameters of the controller were adjusted to reduce by on-line system the error of the speed of IM. In this process, EBPA NN was constituted to an output error value of an IM and conspired an input and output. The performance of the self-tuning controller is compared with that of the PID controller tuned by conventional method (Ziehler-Nichols). The effectiveness of the proposed control method is verified thought the Matlab Simulink and experimental results.

국소성 뇌경색에 미치는 고혈당의 영향에 대한 실험적 연구

권택현,박윤관,정용구,정흥섭,서중근,이훈갑,주정화,이기찬 대한신경외과학회 1992 Journal of Korean neurosurgical society Vol.21 No.1

The present study was undertaken to investigate the influence of hyperglycemia on focal cerebral ischemia in view of morphometric assay and neuropathological examination. Forty Sprague-Dawley rats were divided into two groups of 20 each Rat MCA occlusion model was used for induction of focal ischemia. Hyperglycemia(20 rats, mean±SEM plasma glucose concentration 378±97.6㎎/㎗) was established 30 minutes before MCA occlusion by intraperitoneal injection of 50% dextrose in water ; the control group(20 rats, mean±SEM plasma glucose concentration 121±24.9㎎/㎗) received normal saline only. Twenty-four hours after MCA occlusion neutral red staining and perfusion fixation was performed and ischemic area were measured using computerized image analysis on cortical surface and coronal cut surface. There was no signifcant difference on coronal cut surface, but on cortical surface showed increase of non-stained area(infarct core) and decrease of lightly stained area(transitional zone) in hyperglycemic rats(p<0.05) and the sum of two area was not different between two groups. Pathological findings were evaluated under light microscopy, in which the field scanning was carried out from the midline by 0.5㎜ interval at cortical and basal ganglia level. There showed no significant difference at basal ganglia level, but at cortical level ischemic transitional zone was decreased in hyperglycemic rats(p<0.05). We conclude that hyperglycemia may worsen the brain from severe, focal ischemic neuronal damage.

두개인두종에 대한 수술경험

권택현,정용구,조태형,정흥섭,이기찬,이훈갑 대한신경외과학회 1997 Journal of Korean neurosurgical society Vol.26 No.5

체강의 접근법으로 치험한 동맥류성 골낭 : 증례보고 Case Report

권택현,서중근,박정율,이훈갑 대한신경외과학회 1996 Journal of Korean neurosurgical society Vol.25 No.12

A neurysmal bone cyst is an uncommon spinal tumor of vascular origin and represents less than 1% of primary bone tumors. A case of 15-year-old girl who presented with low back pain and severe left leg pain. The lesion was expansile in nature involving anterior and posterior bony elements of the spine. It also showed expansion into the intraspinal canal and paraspinal soft tissue, Surgical treatment consisted of tumor excision and pedicte screw fixation via extracavitary approach. Postoperative course was uneventful and her symptoms and signs were improved Extracavitary approach as applied to our case seemed to be an ideal surgical method in such cases because of its nature and extent of involvement.

프로락틴선종에 대한 수술적 치료 효과

권택현,정용구,조태형,박정율,박윤관,정흥섭,이기찬,이훈갑 대한신경외과학회 1998 Journal of Korean neurosurgical society Vol.27 No.3

뇌경색후 Lipid Peroxidation에 미치는 Allopurinol 및 Deferoxamine의 효과에 대한 실험적 연구

권택현,박윤관,정용구,정흥섭,서중근,이훈갑,주정화,이기찬 대한신경외과학회 1992 Journal of Korean neurosurgical society Vol.21 No.1

It has been hypothesized that ischemia, followed by reperfusion, facilitates peroxidative free radical chain process in brain. This study was undertaken to investigate the effect of allopurinol and deferoxamine on cerebral lipid peroxidation, estimated by a thiobarbituric acid test, following transient bilateral forebrain ischemia in the rat model of four vessel occlusion. Sprague-Dawley rats fed ad libitum were subjected to transient but severe forebrain ischemia by permanently occluding the vertebral arteries and 48 hours later temporarily occluding the common carotid arteries for 20minutes. Carotid artery blood flow was restored and rats were decapitated after 48 hours. We assessed the lipid peroxidation capacity of cerebral homogenates obtained from hippocampus, basal ganglia, cortex and thalamus. The homogenates were subjected to 30 minutes of aerobic incubation. The production of lipid peroxides were decreased in all sampled area in the treated groups compared with the control group. Allopurinol and deferoxamine-treated groups showed decreased lipid peroxide levels in all the sampled area, but especially more in the hippocampus, (p=0.02), (p<0.01) repecxtively. Combined group (allopurinol and deferoxamine) showed decreased lipid peroxide levels in all the sampled area, but was not statistcally significant(p>0.05). The results suggest that allopurinol and deferoxamine play a role in protecting ischemic cellular damages by scavenging free radicals and subsequently lipid peroxides formed by oxygen supply through blood reperfusion.

포장술을 시행한 뇌동맥류의 치료 성적

권택현,정흥섭,박윤관,조태형,임동준,박정율,정용구,이훈갑,이기찬,서중근,Kwon, Taek Hyun,Chung, Hung Seob,Park, Youn Kwan,Cho, Tai Hyoung,Lim, Dong Jun,Park, Jung Yul,Chung, Yong Gu,Lee, Hoon Kap,Lee, Ki Chan,Suh, Jung Keun 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.7

Objective : Although surgical clipping of intracranial aneurysm is the definite method of treatment, there remains a small number of patients in whom surgical clipping is not technically possible. In such difficult cases, surgeon has to consider other therapeutic alternatives. In this report, we analyze our aneurysmal cases treated by wrapping and coating method and evaluate their surgical outcome and follow-up results. Method : Among the total of 877 patients operated from 1990 to 1999 for intracranial aneurysms at our hospital, 40 cases(4.6%) were treated by wrapping and coating method. They included 24 cases of single ruptured aneurysms and 16 with unruptured ones in multiple aneurysms. Wrapping with temporalis muscle and/or muslin gauze and coating with bioadhesive agent such as fibrin glue were performed. Result : Wrapping and coating method was performed mostly to the anterior communicating artery aneurysm (35%), and mostly because of the broad-based neck of an aneurysm(43%). At the time of discharge, 30 out of 40 patients(80%) showed favourable outcome and three cases died. The patients were monitored for average of 37 months(3-75 months). Among 24 cases with single ruptured aneurysm, 4 cases(17%) had early rebleeding within 6 months from the initial hemorrhage, and such rebleeding occurred within the first postoperative month in 3 cases. However, there was no rebleeding after the 6 months. Among 16 patients whose aneurysms were unruptured ones, none of them showed bleeding episode. Conclusion : It seems likely that the wrapping and coating method would be some help to prevent the rebleeding of an intracranial aneurysm. In order to obtain more accurate results regarding the efficacy of such method, it will be necessary to perform a multi-center study for longer follow-up periods and various wrapping and coating materials.

자기성찰적 여가 참여와 삶의 만족도 간의 관계 연구

권장욱(Kwon, Jang-Wook),이훈(Lee, Hoon) 한양대학교 관광연구소 2018 觀光硏究論叢 Vol.30 No.3

본 연구목적은 비교와 적응을 억제하는 자기성찰적 여가인 요가와 명상 참여가 삶의 만족도에 미치는 영향을 확인하고, 나아가 여가활동 참여와 삶의 만족도 사이에서 자기성찰이 매개역할을 하는지를 검증하고자 하였다. 연구 결과, 명상과 요가 활동 참여는 자기성찰을 구성하는 자기이해와 자기조절에 영향을 미쳤고, 동시에 삶의 만족도에도 영향을 미쳤다. 반면, 자기성찰 중 자기이해는 삶의 만족도에 영향을 미치지 않았고, 자기조절만이 삶의 만족도에 영향을 주었다. 한편, 수정된 구조모형을 통해 분석해 본 결과, 자기이해는 삶의 만족도에는 영향을 미치지 않았지만 자기조절에 영향을 주었고 여가활동 참여와 자기조절을 매개하고 있었다. 따라서 같은 자기성찰을 구성하는 자기이해와 자기조절임에도 불구하고 삶의 만족도에 미치는 역할에 차이가 있다는 것을 알 수 있었다. 이 같은 결과는, 명상과 요가 활동 참여의 경우 먼저 자신에 대한 이해도를 높여주지만 그것이 바로 행복감의 상승으로 연결되지 않으며, 자기이해를 자기조절로 발전시켰을 때에 비로소 행복감이 상승된다는 점을 시사하고 있다. The purpose of the study is to clarify the effect of leisure-activity participation such as mindfulness and yoga activities on life satisfaction, and to verify whether Introspection plays a mediating role between leisure-activity participation and life satisfaction. The results showed that participation in mindfulness and yoga activities had a significant effect on self-awareness and self-regulation of Introspection, and also had a significant effect on life satisfaction. On the other hand, self-awareness did not have a significant effect on life satisfaction, and only self-regulation had a significant effect on life satisfaction. On the other hand, as a result of analyzing through the revised structural model, self-awareness did not affect the life satisfaction but it affected self-regulation and mediated leisure activity participation and self-regulation. Therefore, it was found that there is a difference in the role of life satisfaction in self-awareness and self-regulation. However, in the influence on the satisfaction of life, self-awareness did not directly affect the satisfaction of life, but only played a role as a mediator to raise self-regulation. These results suggest that the participation of mindfulness and yoga activities increases the understanding of oneself first but it does not lead directly to the increase of happiness level and suggests that happiness level can be raised only when self-regulation is strong.

여행에서 나타나는 즉흥성의 양태에 관한 담론

권장욱,이훈 한양대학교 관광연구소 2024 觀光硏究論叢 Vol.36 No.1

This study aimed to identify improvisation in travel and understand its attributes and situations. Literature on improvisation was reviewed in various art fields such as avant-garde art, dance, and behavioral economics. Subsequently, characteristics similar to improvisation in travel, such as independent travel and coincidental experiences, were considered. From this, the features and significance of improvisation in travel were derived. Improvisation in travel is defined as the occurrence of unplanned events, such as insufficient information and unconfirmed schedules, leading to indeterminacy and uncertainty. The attributes associated with improvisation include risk-taking, attention, intuition, freedom, and impulsive decision-making. Consequently, improvisation in travel fosters creativity and serendipitous encounters. Creativity distinguishes one traveler from another, while serendipity adds meaning through admiration and reflection. Thus, ‘improvisation in travel’ is defined as ‘travel that involves making choices and engaging in activities freely, intuitively, and impulsively depending on the situation, without extensive planning.’ This study holds academic significance as it lays the groundwork for future research on spontaneity in travel, drawing from previous studies on spontaneity in tourism and other fields. It is hoped that ongoing research will continue to explore this area further.