• Proceedings of the ESK Conference
• /
• 1997.10a
• /
• pp.414-425
• /
• 1997

Standark polysomnograms, and questionnaires were measured using 4 subjects during simulated 150m heliox saturation dives. These measurements were performed on 4 pre-dive nights, 8 bottom nights, 6 decompression nights and post decompression nights. Sleep disturbances caused by frequent awakening were found throughout the dive period, but the disturbances were more intense on the second and fourth nights at the bottom and on the third and fourth nights of decompression. Stage 4 of sleep decreased every night at the bottom and from the first through third nights of decompression. The subjective self-evaluation of sleep was in agreement with the physiological variables. Complaints of subjective feeling of fatigue slightly increased throughout the dive period. It could be surmised that sleep disturbance or fatigue was not as significant under the 150m deep hyperbalic environment of He-O/ sub 2/ mixture, and therefore should be able to be coped with partially, through there moght be individual differences in adaptation.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2011.09a
• /
• pp.43-46
• /
• 2011

The noise characteristics of multi-purpose dive support vessel show the different patterns such as types of noise sources, accommodation arrangement and etc due to its operation. Especially, the tunnel and retractable thruster for the dynamic positioning should be considered at the noise analysis. The floating floor is selected as the main measure of noise reduction and is constructed at the deck near the noise sources. In this paper, the noise analysis of dive support vessel is based on the estimation of noise sources and floating floor and SEA (Statistical Energy Analysis) is used for analysis of the air-born noise and structure-borne noise. The noise analysis of air conditioning system is also carried out and the noise results of cabin room are reviewed.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.9
• /
• pp.781-788
• /
• 2013

Grunt(stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1 kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.10a
• /
• pp.743-749
• /
• 2012

Grunt (Stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

• Journal of the Korean Society of Safety
• /
• v.34 no.4
• /
• pp.103-110
• /
• 2019

Underwater works are indispensable in the coastal and ocean engineering fields, and the reliance on manpower is higher than land works. Divers who work for a long time in a high-pressure underwater environment are always exposed to the risks of diving-related diseases. To prevent them, proper planning, operation, and management of diving by a supervisor with professional diving knowledge are required. This study provides the basic data for supervisors to plan, operate, and manage air diving for safe and efficient work in underwater construction sites. It is well-known that air diving simulations using the varying permeability model (VPM) require a longer decompression time as the water depth and the residence time in water increase. Therefore, it is crucial to have a proper surface interval through repetitive diving rather than single diving to improve the safety of the divers and the efficiency of underwater work. Furthermore, coastal and ocean engineers who manage and supervise underwater construction work must acquire expert knowledge on diving before they can plan, operate, and manage diving.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2007.12a
• /
• pp.133-135
• /
• 2007

본 연구는 동남아 각국에서 시행되고 있는 레저 스쿠버 잠수 인증 제도에 대한 자료를 수집하고, 잠수 현황 및 인중 현황을 비교하였다. 자료 수집을 위해 인터넷에 게시된 내용을 많이 활용하였고, 관련 문헌을 조사하였으며, 자료 보완을 위해 잠수 협회 관계자, 2007년 동남아 각국의 DIVE EXPO 에 참가한 동남아 각국의 관공홍보 정부 관계자, 잠수 리조트 운영자 및 강사들과 폭 넓은 인터뷰를 하였다. 논문에는 인증 제도에 대한 이해를 돕기 위해 스쿠버 잠수 인증 단체의 설립 역사를 간략히 소개하였고, 스쿠버 인증과 국채 표준의 관계에 대해서도 언급하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.845-849
• /
• 1992

The disturbance and time delay can often cause a significant error in the estimation of trajectory of a underwater vehicle. The time delay considered in this study is due to the delayed rudder response to the rudder input from the guidance control part. The simulation tests are performed on maneuver with constant rudder angle, zigzag maneuver, dive-climb maneuver, and corridor pattern maneuver. The results are compared with those of without delay cases.

• Proceedings of KOSOMES biannual meeting
• /
• 2017.04a
• /
• pp.111-111
• /
• 2017

• Korean Journal of Applied Biomechanics
• /
• v.18 no.1
• /
• pp.53-62
• /
• 2008

The purpose of this research was to analyze the kinematics of the 205B movement in platform diving. For the experiment, 2 athlete from the national diving team were chosen as the subject and two S -VHS video cameras were used. For this diving players preparing for the olympics participated. It was shown that the mean total took $1.112{\pm}0.12s$. In order to perform better, the divers time must be increased, at take off and rotation must be done high up and the horizontal distance must be shorted to main entrance of the water. To enter the water safely, the jump has to be high, the horizontal speed slow and the vertical speed as fast as possible. At E1 the lower limbs change in speed should decrease and after the rotation begins at E2. At take off, the jump is more important than the rotation for the performance of the dive. At take off, the trunk angular velocity was high, and this was needed to jump high for moment of inertia for rotation because for efficient jumping the upper body has to spread out and increase the height of the center of mass.

• The Korean Journal of Malacology
• /
• v.26 no.4
• /
• pp.311-316
• /
• 2010

Spermatid differentiations during spermiogenesis and mature sperm ultrastructure in male Crassostrea nipponica were investigated by transmission electron microscope observations. The morphology of the spermatozoon of this species has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle and an axial rod in subacrosomal materials on an oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres, which appear near the distal centriole. The acrosomal vesicle of spermatozoa of C. nipponica resemble to those of other investigated ostreids. Especially, two transverse bands (stripes) appear at the anterior region of the acrosomal vesicle, unlikely 2-3 transverse bands (stripes) in C. gigas. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The sperm is approximately $48-50{\mu}m$ in length including an oval sperm nucleus (about $1.0{\mu}m$ in length and $1.41{\mu}m$ in width), an acrosome (about $0.48{\mu}m$ in length and 0.30 in width) and tail flagellum ($46-48{\mu}m$). The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9 + 2 structure. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.