• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.53 no.2
• /
• pp.160-168
• /
• 2017

In this study, we propose a method of optimal placement technique of artificial reef considering characteristics of sea areas and provide basic data for efficient budget execution. In addition, we will contribute to increasing the economic efficiency by improving the fisheries productivity by suggesting the scientific basis for the policy data and the increase of the catch through the resource creation based on the ecological information about the biology. Especially, in order to establish the effective disposition (optimum separation distance) of artificial reef considering characteristics of biological and engineering factors, it is necessary to review the artificial reef installation management regulations and investigate the biological effects of artificial reef facilities, is needed. Through this, it is expected that the ground data of the direction of the policy promotion will be derived by suggesting the placement condition of the artificial reef complex which can maximize the resource composition effect according to the target fish species.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.2
• /
• pp.95-100
• /
• 2007

An experimental study was performed to evaluate the in-plate evaporation heat transfer and flow characteristics of a evaporator used in automobile. Two test-cores with different heat transfer area, bead-shape and bead-array were tested, A type and B type. For the heat transfer, Nusselt number for B type test-core reaches a value nearly equal to the one for A type test-core, in the whole range of equivalent Reynolds number. But, for the same mass flow rate of refrigerant, hA for B type test-core becomes higher with the increase of the mass quality of refrigerant than for A type test-core. In a flow visualization experiment, the wake zone of refrigerant circulating at u-turn position of plate is observed.

• Journal of Navigation and Port Research
• /
• v.27 no.5
• /
• pp.473-478
• /
• 2003

Numerical study was made on the flow characteristics around a circular pipeline between parallel walls. The incompressible Navier-Stokes equations were solved by using a third-order upwind differential scheme. When the distance near a wall is small enough, the vortex shedding is almost completely suppressed because of the interaction with the wall boundary layer separation. This study aims to clarify the characteristics of the vortex shedding regime as the body approaches a wall as Reynolds number varies. The feature of separated vorticity dynamics is analyzed at different conditions with particular attention to the interaction between the pipeline wake and the induced separation on the plane walls.

• Journal of the Society of Naval Architects of Korea
• /
• v.41 no.6
• /
• pp.24-32
• /
• 2004

The effects of guide vanes and tip clearances on the characteristics nf axial flow fans are investigated both computationally and experimentally. Performance test of fans carried out in full scale shows considerable effects of tip clearance between rotor tip and duct on the characteristics of fans. The tested results are compared with the computation based on the finite volume method to solve the Navier-Stoke equations with $textsc{k}$-$\varepsilon$ turbulence model. The comparison shows good agreements between experimental and computational results. In addition, the effects of shape of guide vanes are numerically studied. The results show that increased volume of separated region around the guide vane reduces the recovery of tangential component of kinetic energy in the wake, resulting in loss of efficiency

• Journal of computational fluids engineering
• /
• v.7 no.4
• /
• pp.35-41
• /
• 2002

The projectile afterbodies for zero-lift drag reduction has been analyzed using the Navier-Stokes equations with the κ-εturbidence model. The numerical method of a second order upwind scheme has been used on an unstructured adaptive grid system. Base drag reduction methods that have been found effective on axisymmetric bodies are boattailing, base bleed, base combustion, locked vortex afterbodies and multistep afterbodies. In this paper, turbulence flow and pressure charateristics have been studied for geometries of multistep afterbodies. The important geometrical and flow parameters relevant to the design of such afterbodies have been identified by step number, length and height. The flow over multistep aftoerbodies or base have many kinds of compressible flow characteristics including expansion waves at the trailing edge, recompression waves, separation and recirculating flow in the base region, shear flow and wake flow. The numerical results have been compared and analyzed with the experimental data. The flow characteristics have been clearly shown.

• Journal of The Korean Digital Architecture Interior Association
• /
• v.6 no.1
• /
• pp.25-32
• /
• 2006

This paper is a study on the anthroposophic characteristics shown in the first Goetheanum. Rudolf Steiner promoted anthroposophy base on the critique of modem times. His philosophy has developed in various areas such as medical science, agriculture, education, and art. In particular, his thinking was well expressed in the first Goetheanum which was built for Anthroposophical Society. The anthrososophic architectural theory is defined here as application of cosmology, metamorphology and geometry. Steiner defined geometry as a unconscious awareness inscribed in skeletal system of human body as humans have evolved in the process of cosmological development. As a result, Steiner's architecture was able to create metamorphological spaces with harmonizing geometric and organic factors. In respect of decoration, the shapes of plants applied to the decoration still kept individuality because of being made manually, thus perfect symmetrical architecture was impossible. Moreover, the first Goetheanum placed an emphasis on formative dynamics. This was to wake an individual's self-conscienceless up, by enabling him to experience with all the senses without reasoning from the precedent.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.17 no.2
• /
• pp.169-176
• /
• 2010

Purpose: This study was done to investigate clinical characteristics and risk factors for sleep disturbance in patients with prostate cancer. Method: Participants were recruited from P hospital outpatient clinic from March 23 to April 20, 2006, and 101 participants completed a questionnaire assessing general and clinical characteristics, sleep quality, physical symptoms and psychological symptoms such as anxiety and depression. The data was analyzed using the SPSS 12.0 program. Results: In this study, 29.7% of the patients reported sleep disturbance. Cancer diagnosis related factors which affected sleep disturbance were onset (55.3%) and aggravation (83.3%). Habitual sleep efficiency of patients with sleep disturbance was as follows: bedtime was 10 PM, wake-up time was 6AM, sleep duration was six hours and twenty minutes. Risk factors for the presence of sleep disturbance included metastasis, the presence of intestinal symptoms, depression and anxiety. Conclusion: Sleep disturbance is a frequent problem associated with prostate cancer and seems to be influenced by aggravation of illness and the presence of physical and psychological symptoms.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.9
• /
• pp.1335-1348
• /
• 1998

Flow characteristics in transitional boundary layers on a flat plate were experimentally investigated under three different freestream conditions i. e. uniform flow with 0.1 % and 3.7% freestream turbulent intensity and cylinder-wake with 3.7% maximum turbulent intensity. Instantaneous streamwise velocities in laminar, transitional and turbulent boundary layers were measured by I-type hot-wire probe. For estimation of wall shear stresses on the flat plate, measured mean velocities near the wall were applied to the principle of Computational Preston Tube Method (CPM). Distributions of skin friction coefficients were reasonably predicted in all developed boundary layers. Intermittency profiles, which were estimated using Conditional Sampling Technique in transitional boundary layers, were also consistent with previously published data. It was predicted that the incoming turbulent intensity had more influence on transition onset point and transition process than freestream turbulent intensity existed just over the transition region. It was also confirmed that non-turbulent and turbulent profiles in transitional boundary layers could not be simply treated as Blasius and fully turbulent profiles.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.9
• /
• pp.1277-1289
• /
• 1998

The objective of the present study is to investigate experimentally the mean flow characteristics of the three-dimensional turbulent boundary layer over a rotating disk with an impinging jet at the center of the disk, which may be regarded as one of the simplest models for the flow in turbomachinery. A relatively strong radial outflow (crossflow) generated from the impinging jet is added to the radial outflow (crossflow) induced by the centrifugal force in order to create the three-dimensional boundary layer. A new calibration technique has been introduced to determine the velocity direction and magnitude using an I-wire probe, where the uncertainties are ${\pm}1.5^{\circ}$ and ${\pm}0.35\;m/s$, respectively, in the laminar boundary layer region, compared with the known exact solutions. The flow in the tangential direction is of similar type to that associated with a favorable pressure gradient, considering that no wake region appears in wall coordinate velocity profiles and the Clauser shape factor is between 4.0 and 5.3. The flow angle is significantly changed by the crossflow generated by the impinging jet.

• Journal of Ship and Ocean Technology
• /
• v.12 no.2
• /
• pp.41-52
• /
• 2008

The development of a high-lift rudder is needed because low speed full ships such as the VLCC(Very Large Crude oil Carrier) have difficulty for obtaining enough lifting force from a common rudder. The rudder of a ship is generally positioned behind the hull and propeller. Therefore, rudder design should consider the interactions between hull, propeller, and rudder. In the present study, the FLUENT code and body fitted mesh systems generated by the GRIDGEN program are adopted for the numerical simulations of flow characteristics around a rudder that is interacting with hull and propeller. Sliding mesh model(SMM) is adopted to analyze the interaction between propeller rotation and wake flow behind hull. Several numerical simulations are performed to compare the interactions such as hull-rudder, propeller-rudder, and hull-propeller-rudder. Also, we consider relationships between the interactions. The results of present numerical simulations show the variation of flow characteristics by the interaction between hull, propeller, and rudder, and these results are compared with an existing experimental result. The present study demonstrates that numerical simulations can be used effectively in the design of high-lift rudder behind low speed full ship.