횡하중을 받는 SiC/Ti-15-3 MMC 복합재 계면영역에서의 탄소성 응력장분포거동(Ⅰ)

강지웅,김상태,권오헌 한국안전학회 2004 한국안전학회지 Vol.19 No.4

Unidirectional fiber-metal matrix composites have superior mechanical properties along the longitudinal direction. However, the applicability of continuous fiber reinforced MMCs is somewhat limited due to their relatively poor transverse properties. Therefore, the transverse properties of MMCs are significantly influenced by the properties of the fiber/matrix interface. In this study, the interfacial stress states of transversely loaded unidirectional fiber reinforced metal matrix composites investigated by using elastic-plastic finite element analysis. Different fiber volume fractions (5-60%) were studied numerically. The interface was treated as three thin layer (with different properties) with a finite thickness between the fiber and the matrix. The fiber is modeled as transversely isotropic linear-elastic, and the matrix as isotropic elastic-plastic material. The analyses were based on a two-dimensional generalized plane strain model of a cross-section of an unidirectional composite by the ANSYS finite element analysis code.

農業技術 弘報用 印刷媒體의 製作活用改善에 관한 硏究

金性洙,崔敏浩,鄭址雄,權一男 서울大學校 農科大學 1986 서울대농학연구지 Vol.11 No.1

The objectives of the study were to: 1) analyze the structure and styles of the printed media for agricultural information, 2) review the utilization of the magazine by farmers and extension workers, 3) survey the needs of subscribers for the printed media, 4) find ways for improvement in putting out the magazine, and 5) recommend effective methods for publication and utilization of the printed media. Data were collected by mail and group interview from 179 of the randomly sampled farmers and from 148 of the extension agents in selected areas in Korea. The data were analyzed by HP 3000 computer in the College of Agriculture, Seoul National University. Major statistical techniques used for the study were frequency distrbution, percentile. The results of the study were as follows: 1. Communication exposure of the farmers to the printed media was lower than that of the extension agents, however the level of exposure was considerably high considering limited number of copy for farmers. 2. Farmers' major channel for acquisition of new farming technology was personal communication with extension agents, and extension agents' major channel for advanced technology was printed media. 3. It was revealed that the farmers did not have any difficulty in understanding contents of the printed media. 4. The printed media had been providing long range information for the farmers and extension agents. The farmers and extension agents responded that the consistency in the table of contents and the articles was good, and they liked the idea of emphasis by adopting the box style editing. 5. The farmers responded that the topics of the magazine should reflect the current change in agriculture. 8. The farmers responded that they would like to see articles on horticulture and successful case stories in farming. 9. The farmer-subscriber fully utilized information on farming and rural life in the printed media. Extended distrubution of the printed media would be necessary to enlarge the benefit from the advanced farming technology and improved rural home life.

Treatment Results and Prognostic Factors of Brain Metastases From Ovarian Cancer: A Single Institutional Experience of 56 Patients

Kwon, Ji-Woong,Yoon, Joon Ho,Lim, Myong Cheol,Joo, Jungnam,Yoo, Heon,Shin, Sang-Hoon,Park, Sang Yoon,Lee, Sang Hyeon,Kim, Yeon-Joo,Kim, Joo-Young,Gwak, Ho-Shin Blackwell Scientific Publications 2018 International journal of gynecological cancer Vol.28 No.8

<B>Objectives</B><P>The most appropriate treatments for brain metastases from ovarian cancer have not been established mainly because of its rarity. The objective of this study was to describe clinical results of treatment and prognostic factors of patients with brain metastases from ovarian cancer treated at a single institution.</P><B>Materials and Methods</B><P>We retrieved information from the electronic medical records of 56 consecutive patients (2.8%) with brain metastases, from a total of 2008 patients with ovarian cancer. Endpoints were the pattern of treatment failure, progression-free survival, and overall survival (OS).</P><B>Results</B><P>Radiation was the most common initial treatment for brain metastases (59%), followed by surgery (23%). The median progression-free survival was 9.8 months. Radiological progression was confirmed in 20 patients: 7 had leptomeningeal carcinomatosis (37%), 8 had local recurrence, and 5 had distant recurrence. Median OS was 11.25 months, and the 1-year OS rate was 48.2%. Patients received surgery for single metastasis as initial treatment showed median OS of 24.1 months, which was significantly prolonged compared with the other patients (<I>P</I> = 0.0002). Of the 48 patients who died, 29 (60%) died of systemic disease and 7 (15%) died of central nervous system progression. Karnofsky Performance Status greater than or equal to 70, control of systemic cancer, serous histology, and surgery for brain metastases were associated with improved OS in multivariable analysis (<I>P</I> < 0.05).</P><B>Conclusions</B><P>Surgical resection for single or symptomatic brain metastases from ovarian cancer prolonged OS significantly. Multimodality treatment, including control of systemic cancer, appeared to be an important factor in prolonging OS.</P>

Herpes simplex encephalitis after craniopharyngioma surgery

Kwon, Ji-Woong,Cho, Byung-Kyu,Kim, Eui Chong,Wang, Kyu-Chang,Kim, Seung-Ki Journal of Neurosurgery Publishing Group 2008 Journal of neurosurgery. Pediatrics Vol.2 No.5

<P>A 13-year-old girl exhibited rapid deterioration in mental status 15 days after surgery for craniopharyngioma. Serial CT scanning detected progression of a low-density lesion on the left frontotemporal lobe. The serum level of C-reactive protein was elevated and polymerase chain reaction identified herpes simplex virus DNA in the cerebrospinal fluid. Antiviral therapy with high-dose acyclovir (10 mg/kg 3 times daily) was begun. She recovered and could speak short sentences, but dysphasia and right hemiparesis remained. Early diagnosis and active treatment of herpes simplex encephalitis is essential for improving prognosis and saving lives.</P>

Prevalence and Progression of Stage 0 Macular Hole in Fellow Eyes of Patients with Idiopathic Full-thickness Macular Hole

Ji Woong Chun,Chang Hwan Kim,Ju Young Kim,Hyun Sub Oh,Soon Hyun Kim,Oh Woong Kwon,Yong Sung You 대한안과학회 2021 Korean Journal of Ophthalmology Vol.35 No.2

Purpose: To assess the prevalence and progression of a stage 0 macular hole in the fellow eye of patients with an idiopathicfull-thickness macular hole. Methods: The fellow eyes of 189 patients who underwent idiopathic full-thickness macular hole surgery were examinedby biomicroscopy and spectral domain-optical coherence tomography (SD-OCT). A subset of 21 fellow eyes with a stage 0macular hole was observed. Changes in the macular hole were evaluated by biomicroscopy and SD-OCT for an average of 29months. Results: Among the 21 eyes, 15 showed no change in perifoveal vitreous detachment (71.4%). Two eyes (9.5%) developedcomplete vitreofoveal separation, and one of the two developed a separation after progression to stage 1A. Among 21 eyes,5 (23.8%) developed above stage 1A, and one of the five progressed to stage 1B after five years, which was successfullytreated with vitrectomy and gas tamponade. Conclusions: Perifoveal vitreous detachment in the fellow eye on SD-OCT, defined as a stage 0 macular hole, occurred at anearlier phase than stage 1A macular holes and may progress to an advanced stage. Therefore, patients who undergo macularhole surgery and have a stage 0 macular hole or perifoveal vitreous detachment in the fellow eye should be followed closely.

Cerebrospinal Fluid Profiles and Their Changes after Intraventricular Chemotherapy as Prognostic or Predictive Markers for Patients with Leptomeningeal Carcinomatosis

Kwon, Ji-Woong,Shim, Youngbo,Gwak, Ho-Shin,Park, Eun Young,Joo, Jungnam,Yoo, Heon,Shin, Sang-Hoon The Korean Neurosurgical Society 2021 Journal of Korean neurosurgical society Vol.64 No.4

Objective : Here, we evaluated whether cerebrospinal fluid (CSF) profiles and their changes after intraventricular chemotherapy for leptomeningeal carcinomatosis (LMC) could predict the treatment response or be prognostic for patient overall survival (OS) along with clinical factors. Methods : Paired 1) pretreatment lumbar, 2) pretreatment ventricular, and 3) posttreatment ventricular samples and their CSF profiles were collected retrospectively from 148 LMC patients who received Ommaya reservoir installation and intraventricular chemotherapy. CSF profile changes were assessed by calculating the differences between posttreatment and pretreatment samples from the same ventricular compartment. CSF cell counts were further differentiated into total and other based on clinical laboratory reports. Results : For the treatment response, a decreased CSF 'total' cell count tended to be associated with a 'controlled' increase in intracranial pressure (ICP) (p=0.059), but other profile changes were not associated with either the control of increased ICP or the cytology response. Among the pretreatment CSF profiles, lumbar protein level and ventricular cell count were significantly correlated with OS in univariable analysis, but they were not significant in multi-variable analysis. Among CSF profile changes, a decrease in 'other' cell count showed worse OS than 'no change' or increased groups (p=0.001). The cytological response was significant for OS, but the hazard ratio of partial remission was paradoxically higher than that of 'no response'. Conclusion : A decrease in other cell count of CSF after intraventricular chemotherapy was associated with poor OS in LMC patients. We suggest that more specific CSF biomarkers of cancer cell origin are needed.

A New Face Detection Method by Hierarchical Color Histogram Analysis

Ji Woong Kwon,Myoung Soo Park,Mun Hyuk Kim,Jin Young Choi 제어로봇시스템학회 2001 제어로봇시스템학회 국제학술대회 논문집 Vol.2001 No.10

다층 구조방정식을 이용한 초등학생의 학급 공동체 의식 및 또래지위와 방어행동의 관계에서 친사회적 행동의 매개효과

권지웅(Kwon, Ji-Woong),박종효(Park, Jong-Hyo) 한국교육심리학회 2021 敎育心理硏究 Vol.35 No.1

본 연구는 초등학교 4, 5, 6학년 1,374명의 학생들(남 50.0%)을 대상으로 ‘학급 공동체 의식’ 및 ‘또래지위’와 ‘방어행동’의 관계에서 작용하는 ‘친사회적행동’의 매개효과를 학생 및 학급 수준에서 확인하고자 하였다. 연구 문제 검증을 위하여 클래스넷 데이터(4차년 1차)를 사용하였다. 학급 공동체 의식과 친사회적 행동은 자기보고 방식으로 측정하였고, 또래지위와 방어행동은 또래지명 방식으로 측정하였다. 다층 구조방정식을 이용하여 분석한 결과는 다음과 같다. 첫째, 학급과 학생 수준 모두 학급 공동체 의식은 친사회적 행동에 정적인 직접 효과를 보였고, 또래지위도 방어행동에 정적인 직접 효과를 보였다. 둘째, 학생 수준에서 또래지위는 친사회적 행동과 방어행동에 정적인 직접 효과를 보였다. 셋째, 학생 수준에서 학급 공동체 의식은 방어행동에 부적인 직접 효과를 보였고 친사회적 행동은 정적인 직접 효과를 보였다. 넷째, 학생 수준에서 친사회적 행동은 학급 공동체 의식과 방어행동 간의 관계에서 부분적으로 매개하는 간접 효과를 보였다. 마지막으로, 학생 수준에서 친사회적 행동은 또래지위와 방어행동 간의 관계에서 부분적으로 매개하는 간접 효과를 보였다. 이런 결과로 볼 때 학급 수준에서 평균적으로 방어행동 비율이 높은 학급은 평균적으로 또래지위가 높은 학생들로 구성되어 있음을 알 수 있으며, 학생 수준에서 학급 공동체 의식과 또래지위가 높은 학생들의 방어행동 역량을 키우기 위해서는 친사회적 행동을 거쳐야 한다는 시사점을 확인할 수 있었다. The purpose of this study is to identify the mediating effect of pro-social behavior in the relationships among sense of class community, peer status, and defending behavior in 1,374 elementary school children (including 50% boys) of the fourth, fifth and sixth grades. The Class-Net (4th wave) data were used to empirically test the research model. Sense of class community and pro-social behavior were measured using a self-report method, whereas defending behavior was assessed using a peer nomination method. The multi-level structural equation modeling (MSEM) analysis revealed the following. First, sense of class community, at both student and class levels, had a positive direct effect on pro-social behavior, and peer status had a positive direct effect on defending behavior. Second, peer status at the student level had a positive direct effect on pro-social and defending behaviors. Third, sense of class community at the student level had a negative direct effect on defending behavior, whereas pro-social behavior had a positive direct effect on defending behavior. Fourth, sense of class community had an indirect partial mediation effect on defending behavior via pro-social behavior at the student level. Finally, pro-social behavior at the student level had an indirect partial mediation effect in the relationship between peer status and defending behavior. Based on these results, it can be concluded that a class with a high ratio of defending behavior consists of students with high peer status at the class level. Moreover, the results of this study suggest that students who have high levels of both “sense of class community” and “peer status” are encouraged to display pro-social behaviors in the classroom in order to play an active role as defenders against peer victimization.

초등학교 고학년 학생들의 학급 공동체 의식 및 친사회적 행동이 학교폭력 가해경험 및 피해경험에 미치는 영향에서 방어행동 매개효과

권지웅(Kwon, ji woong),박종효(Park, jong hyo) 한국교육학회 2021 敎育學硏究 Vol.59 No.2

본 연구의 목적은 학생 수준에서 방어행동이 학급 공동체 의식 및 친사회적 행동이 가해경험 및 피해경험에 미치는 영향을 매개하는지, 그리고 학급수준에서 또래지위와 방어행동을 학급공동체의식이 매개하는지를 확인하는 것이다. 본 연구목적을 달성하기 위하여 클래스넷(ClassNet)의 초등학생 1,208명(남, 50.3%) 데이터를 사용하였다. 친사회적 행동과 학급공동체의식은 자기보고 방식으로 측정하였고, 또래지위와 방어행동 및 가해 피해 경험은 또래지명 방식으로 측정하였다. 다층 구조방정식으로 분석한 결과는 다음과 같다. 첫째, 학생 수준에서 학급 공동체 의식과 방어행동은 가해·피해경험에 부적 관련성을 보였다. 둘째, 학생 수준에서 친사회적 행동은 방어행동에 정적 효과를 보였다. 셋째, 학급 수준에서 또래지위는 학급 공동체 의식과 방어 행동에 정적 관련성을 보였다. 넷째, 학생 수준에서 방어행동은 친사회적 행동과 가해 경험 및 피해 경험 간의 관계를 부분적으로 매개하였다. 학생들의 또래지위가 높은 학급에서는 방어행동이 빈번하게 일어났으며, 특히 개별 학생의 친사회적 행동은 방어행동을 통해 학교폭력 가해행동과 피해행동을 줄이는 데 간접적으로 영향을 미쳤다. 본 연구는 학생과 학교 수준에서 학교폭력 피해행동과 가해행동을 줄이기 위한 교육적 시사점을 제공하였다. This study was designed to answer two questions: (a) whether or not defending behavior mediated the relationships among sense of class community, pro-social behavior, and experiences of bullying and victimization at the student level and (b) whether a sense of class community mediated the relationship between peer status and defending behavior at the class level. The ClassNet data from 1,208 elementary students (50.3% males) were utilized for research purposes. Pro-social behavior and sense of class community were assessed via self-reporting methods, and peer status and defending behavior were evaluated using peer nomination. Data were analyzed with a series of statistical methods, including multi-level structural equation modeling. The results were as follows: (a) sense of class community and defending behavior were negatively associated with experiences of bullying and victimization at the student level, (b) pro-social behavior was positively related to defending behavior at the student level, (c) peer status was associated with sense of class community and defending behavior at the class level, and (d) defending behavior mediated the relationships between pro-social behavior and experiences of bullying and victimization at the student level. While defending behavior frequently occurred in classes with high levels of peer status, pro-social behavior of individual students reduced experiences of being victimized and offended through an increase of defending behavior. These findings provide educational implications for reducing experiences of bullying and victimization at the student and class levels.

새로운 가족, 새로운 주거 그리고 공유주택에 대해서

권지웅(Kwon, Ji-Woong) 대한건축학회 2016 建築 Vol.60 No.6