• Title/Summary/Keyword: 유영철

Search Result 192, Processing Time 0.035 seconds

특집 - 기계류부품 신뢰성평가 기술 - 한국적 신뢰성 인증기법의 개념 -

  • Kim, Hyeong-Ui;Yu, Yeong-Cheol
    • 기계와재료
    • /
    • v.21 no.3
    • /
    • pp.6-19
    • /
    • 2009
  • 소비자의 요구수준 향상으로 제품의 구조 및 성능이 점점 복잡해지고 부품수는 증가함에 따라, 시스템을 구성하는 부품의 고장발생으로 인한 경제적 손실예방, 안전성 확보 등을 위하여 신뢰성 중심의 종합적인 품질보증에 대한 요구가 점점 증대되고 있다. 본 글에서는 이러한 구성부품의 신뢰성 제고를 위하여 신뢰성평가센터가 2000년부터 현재까지 약 10년 동안 지속적으로 수행하고 있는, 기본 성능시험을 비롯한 내환경성시험, 안정성시험, 수명시험 등의 종합적이고 체계적인 신뢰성 시험평가와 신뢰성인증 시스템에 대하여 고찰하고, 그 과정에서 독창적으로 정립한 13단계의 한국적 신뢰성 인증기법에 대해 설명하고자 한다.

  • PDF

Comparative Early Developments in Winter Spawned Three Pre-larval Fishes(Gadus macrocephalus, Liparis tanakae, Hexagrammos agrammus) (겨울철 산란하는 대구, 꼼치, 노래미 전기 자어의 발달 비교)

  • Shin, Min Gyu;Lee, So-Gwang;Lee, Jeong-Tae;Gwak, Woo-Seok
    • Korean Journal of Ichthyology
    • /
    • v.30 no.1
    • /
    • pp.9-17
    • /
    • 2018
  • This study investigated how the larvae of three winter-spawning fishes are adapted in a cold water environment by examining the morphology, digestive system, and swimming ability of larvae from three winter-spawning species (Gadus macrocephalus, Liparis tanakae, Hexagrammos agrammus). Data were collected at hatching and first feeding. The results were compared with repored data on several non-winter-spawning species. Mean total lengths at hatching (${\pm}SD$) were $4.35{\pm}0.11mm$, $5.26{\pm}0.08mm$, and $7.48{\pm}0.35mm$ for G. macrocephalus, L. tanakae, and H. agrammus, respectively. Three winter-spawning fishes had well-developed digestive tracts after hatching than those of non-winter-spawning fish larvae. Yolks were intact until 5 days post-hatching in all three species, indicating that they had longer mixed-feeding periods compared with fishes spawned during other seasons. G. macrocephalus, L. tanakae, and H. agrammus larvae had superior cruise and burst speeds (measures of swimming ability) than non-winter-spawning larvae. We conclude that the unique characteristics of these three winter-spawning species are naturally selected adaptations under lower water temperature in winter.

Amplitude Characteristics Analysis of Crosswell Seismic Tomography Data in Underground Cavity (지하공동지역에서 시추공간 탄성파 토모그래피 탐사자료의 진폭특성 분석 : 사례연구)

  • 서기황;유영철;유영준;송무영
    • The Journal of Engineering Geology
    • /
    • v.13 no.1
    • /
    • pp.129-137
    • /
    • 2003
  • We interpreted the seismic signal characteristics from crosswell seismic tomography in the underground cavity like abandoned mines. The first arrival time delay and amplitude attenuation showed clearly at the low velocity zone of cavity and fracture. Also ray density decreased by detour of raypath. As a result of the amplitude spectrum analysis of fresh rock and low velocity zone, there were no noticeable differences of the amplitude up to about 1000Hz frequency, but indicated that the one passed around cavity decreased about 7dB at 2000Hz, and 20dB at 3000Hz. It was possible to compare the signal characteristics between two media by extracting the signal data from the fresh rock zone and the underground cavity through the seismic crosswell tomography.