• Title/Summary/Keyword: 유진동수

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Stability Analysis of Axially Moving Beam with Attached Mass (축방향으로 이송되는 부가질량을 가진 보의 안정성 해석)

  • Hur, Kwan-Do;Son, In-Soo;Ahn, Sung-Jin
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.1
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    • pp.56-61
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    • 2012
  • The dynamic instability and natural frequency of axially moving beam with an attached mass are investigated. Thus, the effects of an attached mass on the stability of the moving beam are studied. The governing equation of motion of the moving beam with an attached mass is derived from the extended Hamilton's principle. The natural frequencies are investigated for the moving beams via the Galerkin method under the simple support boundary. Numerical examples show the effects of the attached mass and moving speed on the stability of moving beam. Moreover, the lowest critical moving speeds for the simple supported conditions have been presented. The results can be used in the analysis of axially moving beams with an attached mass for checking the stability.

The Natural Frequency Sensitivities of the Lower Modes of Ship Hull Vibrations (선체 저차고유진동수의 감도)

  • Y.C. Huh;T.Y. Chung;K.C. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.28 no.1
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    • pp.99-107
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    • 1991
  • In the course of ship basic design, the redesign works to avoid resonance can be carried out efficiently provided that the frequency sensitivities of the baseline system is available. In this paper, for lower modes of ship's hull vibrations, a practical method to predict the natural frequency sensitivities to major design variables subject to considerations at the preliminary design stage is presented. The method is of derivation based on frequency sensitivities of uniform Timoshenko beams eguivalent to actual ships.

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Stability of beck's column with a rotatory spring restraining its free end (자유단이 회전스프링으로 구속된 Beck 기둥의 안정성)

  • Yun, Han-Ik;Im, Sun-Hong;Yu, Jin-Seok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.9
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    • pp.1385-1391
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    • 1997
  • An analysis is presented on the stability of an elastic cantilever column subjected to a concentrated follower force as to the influence of the elastic restraint and a tip mass at the free end. The elastic restraint is formed by the rotatory springs. For this purpose, the governing equations and boundary conditions are derived by using Hamilton's principle, and the critical flutter loads and frequencies are obtained from the numerical evaluation of the eigenvalue functions of the considered system.

Serum Testosterone Levels in Patients with Post-Traumatic Stress Disorder (외상 후 스트레스 장애 환자의 혈청 테스토스테론치)

  • Kim, Dong Su;Kim, Hae Jung;Bang, Yu Jin;Go, Chang Min;Chung, Moon Yong;Kang, Suk Hoon
    • Anxiety and mood
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    • v.9 no.2
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    • pp.106-112
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    • 2013
  • Objective : Several reports have found abnormal levels of androgen in post-traumatic stress disorder (PTSD) patients. This abnormality in androgen is hypothesized to due to chronic psychological stress effects on the hypothalamic-pituitary-gonadal (HPG) system. The present study was conducted to estimate serum testosterone levels in PTSD patients in comparison with normal subjects. Methods : Seventy-five male Korean veterans of the Vietnam War volunteered for the study, of which eleven were excluded because of incomplete psychological assessment. To measure basal serum testosterone, blood samples were collected between 8.00 and 9.30 a.m. The clinician administered PTSD scale (CAPS), the structured clinical interview for DSM-IV (SCID), Hamilton Anxiety Rating Scale (HAM-A), Hamilton Rating Scale for Depression (HAM-D), Mini International Neuropsychiatric Interview Plus (Korean version of MINI-Plus), CES-K (Korean version of combat exposure scale). Results : The serum testosterone level of PTSD patients ($5.4{\pm}2.5ng/mL$) was higher than that of a control group ($3.1{\pm}1.7ng/mL$, p<0.001). Testosterone levels were significantly correlated with CAPS (r=.38, p<.01), HAM-A (r=.35, p<.01) and HAM-D (r=.28, p<.01) in all subjects. Conclusion : The results of the present study suggest that chronic psychological stress affects the HPG system.

Design of e-Learning System in N-Screen Environment (N-Screen 환경 기반의 이러닝 시스템 설계 방안)

  • Shin, Yu-Jin;Seo, Dongsu;Hong, Seng-Phil
    • Journal of Internet Computing and Services
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    • v.13 no.5
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    • pp.45-53
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    • 2012
  • The appearance of Intelligent mobile and home appliance increased the using of not only various multimedia contents but also educational contents. Especially the growth of smart device such as smart phone, smart pad and smart TV, provided the environment which everyone can use educational content anytime, anywhere, any device. However many smart devices are hard to reuse the various educational contents because the devices and mobile os policies are not unify. In this paper, we suggest the design of NeS(N-Screen e-learning system) in order to solve this problem. NeS is consisted of User Management, Educational Content Management, Content Convert System and Interactive Management System. In this system, we use the HTML5 language to assure interoperability in various Smart Device Environment. Through NeS, we can achieve Content OSMU(One Source Multi Use) in various device environment and assure the continuity of the contents for using the educational contents more easily.

Maximization of the Output Voltage of a Cantilevered Energy Harvester Comprising Piezoelectric Fiber Composites (압전섬유복합재 외팔보 에너지 회수장치의 출력전압 최대화)

  • Kim, Seon-Myeong;Kim, Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.7
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    • pp.805-812
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    • 2011
  • In this study, a cantilevered energy harvester comprising piezoelectric fiber and epoxy composites was designed and analyzed electro-mechanically. In order to maximize the power of the cantilevered energy harvester, its exciting frequency was tuned to the first natural frequency of the beam. An efficient analysis method for predicting the output voltage of the beam was developed by using the finite element method coupled with piezoelectric behavior. By using this method, the effects of geometric parameters and various piezoelectric materials on power generation were investigated and the electric characteristics were evaluated. Design optimization of the beam geometries was performed for a base model. The optimum MFC design generated a maximum electric output of 40.1 V at a first natural frequency of 24.5 Hz.

The Application of the Clinician Administered Posttraumatic Stress Disorder Scale to Identify Combat Related Posttraumatic Stress Disorder (전투 관련 외상 후 스트레스 장애 진단에 있어서 임상가를 위한 외상 후 스트레스 장애 척도의 적용)

  • Kim, Hae Jung;Kim, Tae Yong;Choi, Jin Hee;So, Hyung Seok;Chung, Moon Yong;Kim, Dong Su;Bang, Yu Jin;Chung, Hae Gyung
    • Anxiety and mood
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    • v.8 no.2
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    • pp.113-119
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    • 2012
  • Objective : The purpose of this study is to assess the utility of clinician administered posttraumatic stress disorder scale (CAPS) to diagnose combat related posttraumatic stress disorder (PTSD) in Korean veterans of the Vietnam War. Methods : Sixty-one Korean male veterans of the Vietnam war participated in this study. We compared the diagnostic values of CAPS, Korean version of mini international neuropsychiatric interview (MINI) against the Structured Clinical Interview for DSM-IV (SCID) in diagnosing PTSD. Results : The overall internal consistency of CAPS was 0.93. Compared to the SCID, total severity 45 (TSEV45) showed the best results among 5 CAPS scoring rules. In detail, sensitivity was 71.4%, specificity was 85.1, positive predictive value was 58.8%, negative predictive value was 90.9%, and accuracy was 82.0. Conclusion : CAPS was demonstrated as a reliable tool to diagnose combat related PTSD in the elderly. The optimum CAPS scoring was TSEV45.

Survey on the Needs of Korean Medicine Doctor for Community Care Education Programs (한의약 건강돌봄 교육 프로그램에 대한 한의사 요구도 조사)

  • Jihye Kang;Eunji Ahn;Jihyeon Lee;Dongmin Sung;Yujin Han;Dongsu Kim
    • Journal of Society of Preventive Korean Medicine
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    • v.28 no.1
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    • pp.1-11
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    • 2024
  • Objectives : This study conducted a survey on the needs of Korean medicine doctors for health care education programs specializing in traditional Korean medicine. Methods : The study selected Korean medicine doctors who had experience participating in outpatient consultations. Data collected through surveys underwent frequency analysis on performance, importance, difficulty, and educational needs using SPSS 24.0. Additionally, an Importance-Performance Analysis (IPA) was conducted using importance and performance data. Results : According to the results of the IPA analysis, in the area of "keep up the good work" there were activities such as fee Claims (A3), comprehensive assessment (B4), care plan development (B5), client and caregiver interviews (C8), chronic disease monitoring (C9), musculoskeletal and other pain management, musculoskeletal rehabilitation (C10), mental health management (C11), and fall prevention (C15). In the "concentrate here" priority action area, skin care including pressure sore management (C13) was identified. Conclusions : The traditional Korean medicine community care service is expected to expand further, so it is anticipated that the developed educational programs will contribute to the activation of traditional Korean medicine health care business.

The Spread of Black Pine Bast Scale, Matsucoccus thunbergianae (Hemiptera: Margarodidae) in Korea (우리나라에서 솔껍질깍지벌레의 분포확산)

  • Lim, Eu-Gene;Lee, Sang-Myeong;Kim, Dong-Soo;Kim, Joon-Bum;Lee, Shin-Hye;Choi, Kwang-Sik;Park, Chung-Gyoo;Lee, Dong-Woon
    • Korean journal of applied entomology
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    • v.51 no.1
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    • pp.59-65
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    • 2012
  • The black pine bast scale, $Masucoccus$ $thunbergianae$ (Hemiptera: Margarodidae), is a serious pest of the Japanese black pine, $Pinus$ $thunbergii$, in Korea. The distribution of the black pine bast scale was examined, looking overall at 686 towns (eup), townships (myeon) or neighborhoods (dong). There were Japanese black pine ($Pinus$ $thunbergii$) forests in 91 cities, counties (gun) and borough (gu), in seven provinces and three metropolitan cities during 2010. Black pine bast scale were found in 64.8% of cities or counties or borough (59) in 7 provinces and 3 metropolitan cities, and were distributed in all South Costal regions, Pohang in East Costal region and Boryeong in West Costal region. Chungcheongbukdo, Daejeon and Jeju did not have black pine bast scale. All the gu regions in Busan had black pine bast scale, of which the area with the highest prevalence was Haenam in Jeollanamdo (1.713 crawlers/0.785 $cm^2$). Songji-myeon had the highest occurrence rate (6.36 crawlers/0.785 $cm^2$) from the towns, township and dong. The density of black pine bast scale in twigs was highly correlated with percentage of the sample with scale (Correlation coefficacy=0.89).