• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1999.11a
• /
• pp.175-180
• /
• 1999

This paper presents the effective design of the change of average illuminance and the arrangement of lamps by changing the form of working area and adjusting the distance between the wall and light. This study is intended to simplify the complex calculation of illuminance through the development of application program. It's plan to study application programs that can attain the value of advanced uniformly-distributed illuminance and average illuminance by changing the distance between the horizontal/vertical wall and lamp and between the horizontal/vertical lamp and lamp.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.11 no.2
• /
• pp.662-670
• /
• 2019

Tanker cargo tanks are equipped with the means of raising and maintaining the cargo discharge temperature to a suitable level. In this paper, a new heating coil design is proposed and analyzed. Contrary to conventional designs, wherein the heating coils are evenly distributed over the tank bottom, the proposed design arranges the heating coils in the central part of the tank bottom, in a vertical direction. Due to the intensive cargo circulation generated, a forced convection is superimposed on a buoyancy-driven natural convection, providing a more efficient mixed convection heat transfer mechanism. Numerical simulations performed by using a finite volume method show that in the case of 7-bar steam Bunker C heavy fuel oil heating, a five-hour circulation phase average heat transfer coefficient equals 199.2 W/m²K. This result might be taken as an impetus for the more thorough experimental examination.

• Tribology and Lubricants
• /
• v.37 no.6
• /
• pp.224-231
• /
• 2021

Recently, the waterproofing performance of high-voltage connectors in automotive vehicles has attracted increased interest. In this study, an optimal cross-sectional shape was derived to obtain uniform contact pressure and strain by considering stress relaxation problems caused by initial tension when mounting a seal. A high strain of 52.1 was distributed in the round region, owing to excessive initial tension. The finite element method (FEM) analysis indicated that the strain corresponding to the optimal initial tensile was 11. We adopted six design factors to optimize the seal cross-section and three factors as the main design factors. An orthogonal arrangement table was prepared using Minitab. FEM analyses of 16 study models were conducted to determine the optimized model. The contact pressure of the optimization model is the most evenly distributed while satisfying the waterproof performance of 0.47 MPa. Compared to the initial model, the difference in strain decreases from 35.5% to 19.6%. Finally, the derived cross-sectional shape can reduce the strain of the round region by 33.8% and the differences in the contact pressure at the upper and lower surfaces by 42% and 76%, respectively.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.21 no.1
• /
• pp.161-174
• /
• 2010

The purpose of this study is to identify the problems of the reciprocal borrowing service in Korea and to develop the reciprocal borrowing model. Using interview and survey method were used for collecting data. Results show that public librarian had positive thought about reciprocal borrowing service and there were many problems to solve before operating the service. Main problems were: leaking of private information, responsibility of lost materials, budget and staff, borrowing regulation, non-competitive libraries. Also three reciprocal borrowing system models were introduced: integrated system model, distributed system model, and reciprocal arrangement model.

• Steel and Composite Structures
• /
• v.52 no.3
• /
• pp.343-356
• /
• 2024

This paper presents an analytical solution for correctly predicting the Lateral-Torsional Buckling critical moment of simply supported castellated beams, the solution covers uniformly distributed loads combined with compressive loads. For this purpose, the castellated beam section with hexagonal-type perforation is treated as an arrangement of double "T" sections, composed of an upper T section and a lower T section. The castellated beam with regular openings is considered as a periodic repeating structure of unit cells. According to the kinematic model, the energy principle is applied in the context of geometric nonlinearity and the linear elastic behavior of materials. The differential equilibrium equations are established using Galerkin's method and the tangential stiffness matrix is calculated to determine the critical lateral torsional buckling loads. A Finite Element simulation using ABAQUS software is performed to verify the accuracy of the suggested analytical solution, each castellated beam is modelled with appropriate sizes meshes by thin shell elements S8R, the chosen element has 8 nodes and six degrees of freedom per node, including five integration points through the thickness, the Lanczos eigen-solver of ABAQUS was used to conduct elastic buckling analysis. It has been demonstrated that the proposed analytical solution results are in good agreement with those of the finite element method. A parametric study involving geometric and mechanical parameters is carried out, the intensity of the compressive load is also included. In comparison with the linear solution, it has been found that the linear stability underestimates the lateral buckling resistance. It has been confirmed that when high axial loads are applied, an impressive reduction in critical loads has been observed. It can be concluded that the obtained analytical solution is efficient and simple, and offers a rapid and direct method for estimating the lateral torsional buckling critical moment of simply supported castellated beams.

• The Korea Journal of Herbology
• /
• v.26 no.1
• /
• pp.1-6
• /
• 2011

Objectives : Due to morphological similarity, many substitutes and counterfeits have been used as Moktong for thousands of years. This study was designed to determine discriminative criteria for identifying medicinal herbs used as Moktong. Methods : Akebia quinata, A. trifoliata, Clematis armandii, and Aristolochia manshuriensis were collected in various regions. Samples were authenticated and examined by observation and microscopy with paraffin embedding and triple staining using the modified Ju staining method. Results : Three different types of features to establish discriminative criteria for four kinds of Moktong were identified. Botanical features include differences in phyllotaxy, leaf shape, and caulescent. External morphological features were arrangement and size of fine holes(xylem), and overall shape of the section. Internal morphological features include the number of medullary rays, shape of the pitch, type of tissues rounding pitch, appearance of annual rings, shape and amount of crystals(calcium-oxalate), and the appearance of cork cambium. Further details(e.g. identification keys) are in the article. Conclusions : These criteria could provide an effective method for identifying numerous kinds of Moktong distributed in markets throughout northeast Asian nations.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.35 no.5
• /
• pp.1039-1049
• /
• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.

• Korean Institute of Interior Design Journal
• /
• v.20 no.6
• /
• pp.262-271
• /
• 2011

The purpose of this study was to classify types of family visitors' behaviors more concretely, which could be useful in planning of exhibition spaces in a science museum, with given priority to their behaviors according to interaction between them, and to understand characteristics of the behaviors. With this view, the scope of this study was restricted to subjects, who were family visitors of Gwacheon National Science Museum, consisting of parents and their one elementary school child per family unit. For understanding their behaviors, itinerary tracking and observation method of behavior were conducted. Moreover, for understanding substantial types and characteristics of family visitors' behaviors, multivariate analysis was applied. Accordingly, the results of the study are as follows. First, as a result of factor analysis, two main factors were derived. In other words, they were 'Durability of viewing' as the first and 'Interactivity between family members' as the second, which were shown valid in classification of the types of their behaviors. Second, according to the factors derived, the types of their behaviors were classified into in-depth cooperative viewing, selective independent viewing, interest concentration child-led viewing and consideration parent-led viewing. They were shown valid in topological localization and classification, as a result of analysis of the main factors. Third, in view of common characteristics of the types, it is judged that active orientation prior to regular viewing could encourage visitors coming to the museum for the first time to feel more friendly to unfamiliar exhibition environments, during the initial seek time, and to reduce visual supersaturation. Fourth, it is judged that distributed arrangement of exhibits, which result in continuous standby, could avoid confused visitor circulation by the estimated time required for viewing.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.24 no.1
• /
• pp.41-57
• /
• 1997

The present study investigated the effects of hyperbaric oxygen therapy on periodontal wound healing of replanted rat tooth. 80 rats (Sprague-Dawley strain) weighting $130{\pm}5gm$ were selected and divided into experimental and control group, each group consisting of 40 rats. Rats were administered 0.4% ${\beta}$-aminoproprionitrile for 5 days to achieve gentle tooth extraction. The maxillary first molars were extracted under anesthesia with pentobarbital, washed in sterile distilled water, treated with bacterial collagenase to remove collagen fibers on the root surfaces. After washing in water overnight, the mesial root surface were demineralized by application of citric acid, washed, dried and stored at $4^{\circ}C$. Immediately after tooth extraction and bleeding control, the treated molars extracted previously from other rats were replanted. The experimental group was exposed to hyperbaric oxygen at 2.5 atm. for 2 hrs. a day during experimental period. Eight animals of each group were sacrificed 1, 3, 6, 8, 10 days after reimplantation of teeth by intracardiac perfusion with 4% paraformaldehyde. The replanted molars and surrounding tissues were cut, demineralized, dehydrated and embedded in paraffin. Sections were stained with azan, toluidine blue and hematoxylin. Some other sections were stained by means of immunostaining achieved by the avidinbiotin complex method. The results as follows; 1. Experimental group showed fast healing of gingival epithelium. 2. Macrophage and newly formed blood vessels appeared early in the gingival connective tissue of experimental group. 3. Experimental group showed fast, abundant fibroblast proliferation and regularity of collagen fiber. 4. In both group, collagen was distributed along the collagen fiber. The distribution was strong and regular in the experimental group. 5. In the regenerated periodontal ligament of experimental group, fibers showed regular arrangement and invaded root surface fast.

• Journal of Technologic Dentistry
• /
• v.40 no.3
• /
• pp.163-172
• /
• 2018

Purpose: The research comprehends learning attitude level of Dental Technology Department students, searches variable element to affect and is trying to provide basic material of method arrangement to induce change of positive learning attitude. Methods: It was conducted survey 410 students, who understand purpose of the research, consentient to involve research, in universities which is located in Daegu area, Daejeon City, Gangwon province from Aug., 1stto Nov.,10th2017, Questionnaires were distributed to 410 students totally. it was finally analyzed 374 questionnaires except 36 questionnaires that answer was not sufficient. Results: The positive answer over 'Average (3)' among study attitude factors was presented highly in order of 'Targeting & Execution' (3.351). 'Effective Content Summary' (3.307), 'Study Plan' (3.173), 'Priority and Self-Management' (3.116), and 'Study Habit & Enhancement' (2.925) showed negative trend under average. The five sub-factors of learning attitude were examined according to general characteristics and there were statistically significant differences according to gender, grade, high school of origin, academic aptitude(p<0.01, p<0.001). Conclusion : As male students show more positive learning attitude than female students, we need to develop more special programs to encourage them. Meanwhile we also need to find out a motive to bring positive effect to change the academic aptitude and learning attitude of female students, or methods to improve their learning attitude in a complementary way by their high school, gender and grade.