• Journal of Energy Engineering
• /
• v.24 no.4
• /
• pp.71-80
• /
• 2015

Steel stiffener is required for reinforcing the structure of the window frame made of versatile but weak PVC material. Steel stiffener however becomes a source of greater heat loss and frequently plays a role of thermal bridge due to its high thermal conductivity. To maintain thermal resistance similar to PVC frame, steel stiffener is perforated to reduce the effective heat transfer area. To compensate the structural strength of the steel stiffener which is weakened by the perforation, the thickness is increased. Increase in thickness will also increase the thermal heat resistance. Five samples which are PVC frame, PVC frame + original steel stiffener, PVC frame + 30% perforated steel stiffener, PVC frame + 50% perforated steel stiffener, PVC frame + 65% perforated steel stiffener are modeled and simulated for 2nd moment of area and thermal resistance. Therm/window version 6.3 is used for thermal analysis. The results show that among the five samples analyzed, PVC frame + 65% perforated steel stiffener best satisfies both structural strength and thermal resistance.

• Computational Structural Engineering
• /
• v.4 no.4
• /
• pp.135-144
• /
• 1991

The finite element technique incorporatating infinite elements is applied to analyzing the general three dimensional wave-structure interaction problems within the limits of linear wave theory. The hydrodynamic forces are assumed to be inertially dominated, and viscous effects are neglected. In order to analyze the corresponding boundary value problems efficiently, two types of elements are developed. One is the infinite element for modeling the radiation condition at infinity, and the other is the fictitious bottom boundary element for the case of deep water. To validate those elements, numerical analyses are performed for several floating structures. Comparisons with the results by using other available solution methods show that the present method incorporating the infinite and the fictitious bottom boundary elements gives good results.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.27 no.1
• /
• pp.3-10
• /
• 1990

Hull form can be described numerically by two approaches, one is to describe a hull form with a set of curves("curve approach"), and the other is to describe it with surfaces directly("surface approach"). This paper describes the numerical definition scheme of hull form using curve approach method which defines the hull form by a set of curves consisting of 2-dimensional transverse section curves and 3-dimensional longitudinal curves. A set of curves in the hull form definition scheme is described by the modified cubic spline which modified the general parametric cubic spline in order to ensure a very smooth curvature distribution within the curve segment even though a curve segment has large tangent angle at its end points. Illustrative examples are given showing the application of the method to represent the hull form of SWATH ship and oceanographic research vessel. Also, examples for hull form transformation are shown by using this method connected with transformation technique.

• Applied Chemistry for Engineering
• /
• v.18 no.2
• /
• pp.99-110
• /
• 2007

Efficient and inexpensive hydrogen storage is an essential prerequisite for the utilization of hydrogen, one of the new and clean energy sources for $21^{st}$ century. In this review, several storage techniques are briefly reviewed and compared. Especially, adsorption/storage via physisorption at low temperature, by using nanoporous adsorbents, is reviewed and evaluated for further developments. The adsorption over a porous material at low temperature is currently investigated deeply to fulfill the storage target. In this review, several characteristics needed for the high hydrogen adsorption capacity are introduced. It may be summarized that following characteristics are necessary for high storage capacity over porous materials: i) high surface area and micropore volume, ii) narrow pore size, iii) strong electrostatic field, and iv) coordinatively unsaturated sites, etc. Moreover, typical results demonstrating high storage capacity over nanoporous materials are summarized. Storage capacity up to 7.5 wt% at liquid nitrogen temperature and 80 atm is reported. Competitive adsorbents that are suitable for hydrogen storage may be developed via intensive and continuous studies on design, synthesis, manufacturing and modification of nanoporous materials.

• Korean Chemical Engineering Research
• /
• v.40 no.6
• /
• pp.659-663
• /
• 2002

The crystallization of NaF driven by adding ethanol was monitored using quartz crystal analyzer (QCA). Adding ethanol to NaF solution reduced the solubility of NaF and consequently led to nucleation and growth of NaF crystals. To investigate the crystallization behavior of NaF, a gold electrode of QCA was modified by anchoring with 2-mercaptoethylamine hydrochloride based on a self-assembly method. Frequency of QCA varied with the amount of NaF adsorbed on the self-assembled layer of 2-mercaptoethylamine hydrochloride, and thereby the process of NaF crystallization could be analyzed indirectly by monitoring the frequency change of QCA. To change the extent of supersaruration of NaF, the amount of ethanol added to the solution was varied from 1 to 5 ml. Then, the effect of the extent of the supersaturation on the crystallization was examined by analyzing the frequency changes of QCA coated with 2-mercaptoethylamine hydrochloride. It was shown that the QCA technique could be well applied for the characterization and analysis of the crystallization behavior of NaF.

• Journal of the Korean Chemical Society
• /
• v.52 no.1
• /
• pp.57-65
• /
• 2008

are nanometer or micrometer scale vesicles that can be used as drug delivery carriers. However, plain liposomes are plagued by rapid opsonization, making their circulation time in bloodstream be shortened. In this study, model protein, bovine serum albumin (BSA)-coated liposomes were prepared by coating cationic liposomes with BSA molecules at higher pH than isoelectric point of BSA. The BSA molecules coated on the liposomal surface were denatured by thermal treatment at above 60oC. While both plain and cationic liposomes had about mean particle diameter of 1041 nm, BSA-coated cationic liposomes (BCL) had mean particle diameter of 1091 nm. Encapsulation of model drug, doxorubicin (DOX), in liposomes were carried out by using remote loading method and the loading efficiency of DOX to liposomes was about 90%. The mean particle diameter of BCL did not increase in blood plasma and adsorption of plasma protein was much less than plain or cationic liposomes. These results suggest that BCL can be used as a long-circulating liposomes in bloodstream.

• KIPS Transactions on Software and Data Engineering
• /
• v.4 no.10
• /
• pp.465-472
• /
• 2015

We propose a novel plane detection in disparity space and evaluate its performance. Our method simplifies and makes scenes in disparity space easily dealt with by approximating various surfaces as planes. Moreover, the approximated planes can be represented in the same size as in the real world, and can be employed for obstacle detection and camera pose estimation. Using a stereo matching technique, our method first creates a disparity image which consists of binocular disparity values at xy-coordinates in the image. Slants of disparity values are estimated by exploiting a line simplification algorithm which allows our method to reflect global changes against x or y axis. According to pairs of x and y slants, we label the disparity image. 4-connected disparities with the same label are grouped, on which least squared model estimates plane parameters. N plane models with the largest group of disparity values which satisfy their plane parameters are chosen. We quantitatively and qualitatively evaluate our plane detection. The result shows 97.9%와 86.6% of quality in our experiment respectively on cones and cylinders. Proposed method excellently extracts planes from Middlebury and KITTI dataset which are typically used for evaluation of stereo matching algorithms.

• Parasites, Hosts and Diseases
• /
• v.30 no.2
• /
• pp.65-74
• /
• 1992

The tegumental ultrastructure of juvenile and adult Echinostoma cinetorchis (Trematoda: Echinostomatidae) was observed by scanning electron microscopy. Three-day (juvenile) and 16-day (adult) worms were harvested from rats (Sprague-Dawley) experimentally fed the metacercariae from the laboratory-infected fresh water snail, Hippeutis cantori. The worms were fifed with 2.5% glutaraldehyde, processed routinely, and observed by an ISI Korea DS-130 scanning electron microscope. The 3-day old juvenile worms were elongated and ventrally curved, with their ventral sucker near the anterior two-fifths of the body. The head crown was bearing 37∼38 collar spines arranged in a zigzag pattern. The lips of the oral and ventral suckers had 8 and 5 type II sensory papillae respectively, and bewteen the spines, a few type III papillae were observed. Tongue or spade-shape spines were distributed anteriorly to the ventral sucker, whereas peg-like spines were distributed posteriorly and became sparse toward the posterior body. The spines of the dorsal surface were similar to those of the ventral surface. The 16-day old adults were leaf-like, and their oral and ventral suckers were located very closely. Aspinous head crown, oral and ventral suckers had type II and type III sensory papillae, and numerous type I papillae were distributed on the tegument anterior to the ventral sucker. Scale-like spines, with broad base and round tip, were distributed densely on the tegument anterior to the ventral sucker but they became sparse posteriorly. At the dorsal surface, spines were observed at times only at the anterior body. The results showed that the tegument of E. cinetorchis is similar to that of other echinostomes, but differs in the number and arrangement of collar spines, shape and distribution of tegumenal spines, and type and distribution of sensory papillae.

• The Journal of Korean Society for Radiation Therapy
• /
• v.22 no.1
• /
• pp.53-60
• /
• 2010

Purpose: We try to calculate EDW-factor easily with the formula applies essential data of EDW-factor and evaluate the validity through a measurement. Materials and Methods: We used the given value of GSTT (Golden Segmented Treatment Table) for the calculation of the EDW-factor. As to the experimental device, 0.6 cc farmer-type ion-chamber, an electrometer and water- phantom were used. A measurement was made at the maximum dose depth of the photon beam energy 6 MV and 15 MV under the condition that SSD (Source to Surface Distance) was 100 cm. The angle of the EDW (Enhanced Dynamic Wedge) which we use in an experiment was 60 degree, 30 degree, 20 degree in the Y1-OUT direction. We used Eclipse planning system (Varian, USA) as RTP system and the EDW-factor was calculated about all fields and EDW direction. In order to show the EDW-factor feature, a measurement was made at the selected field that verify the influence of the dependability about X, Y jaw and off-axis field. Results: When we change the Y1 field, it influence on the EDW-Factor and measured value. But the error between measured values and calculated values was less than 1%. The experimental result indicated the tendency that the error of the result of calculation and measured value becomes smaller as the EDW angle become smaller whether the calculation point (measurement point) and iso-center are same or not. The influence of the field size and energy did not show up. We simulated with the same condition using the RTP system. And we found that it makes no difference between the MU which is calculated manually by applying the EDW-Factor obtained from the commercial program and the value which is calculated by using RTP system. Conclusion: We excluded fitting value from well-known EDW-Factor formula and calculated EDW-factor with the formula applies essential data of EDW-factor only. As a result, there are no significant difference between the measured value and calculated value and it showed errors less than 1%. Also, we implemented the commercial program to calculate EDW-Factor conveniently without measure a factor on each field.

• Journal of the Korea Society for Simulation
• /
• v.29 no.1
• /
• pp.23-30
• /
• 2020

In this paper, we theoretically examine the characteristics of an Artificial Magnetic Conductor (AMC) constructed of a perfect electric conductor and a normal material having permittivity ε_r, permeability μ_r, and thickness L. First, we derived rigorous equations to describe the infinite AMC structure. Then, we studied how the AMC's characteristics are affected by changes in ε_r, μ_r and L. The operating center frequency exhibiting a 0° reflection coefficient phase occurs when L is one quarter of a guide wavelength. Therefore, the AMC thickness can be reduced by using a material having a high product of ε_r and μ_r. As the ratio μ_r/ε_r increases, the bandwidth of the AMC increases (maximum value: 200 %), and its operating frequency decreases. We also find out he bandwidth of the AMC is improved by introducing a loss in the material. To validate the AMC, we design a dipole antenna on the AMC and demonstrate a relationship between AMC phase and dipole antenna's operating frequency by investigating the dipole on the AMC with different pairs of ε_r and μ_r.