• International Journal of Fluid Machinery and Systems
• /
• v.5 no.3
• /
• pp.100-108
• /
• 2012

Design parameters for suction channels of process centrifugal compressors were investigated, and an optimization method to enhance stage efficiency by using the new design parameters was proposed. From results of computational fluid dynamics, the passage sectional area ratios $A_c/A_e$, $A_e/A_s$ and $A_c/A_s$ were found to be the dominant parameters for the pressure loss and circumferential flow distortion, where $A_c$, $A_e$ and $A_s$ are passage sectional areas for the casing upstream side, casing entrance and impeller eye, respectively. The Base suction channel was optimized using the new design parameters, and the Base and Optimized types were tested. Test results showed that the Optimized suction channel achieved 3.8% higher stage efficiency than the Base suction channel while maintaining the same operating range.

• Advances in Computational Design
• /
• v.3 no.1
• /
• pp.35-47
• /
• 2018

Design of settlement space is a complicated process while reasonable spatial layout bears great significance on the development and resource allocation of a settlement. The study proposes a weighted L-system generation algorithm based on CA (Cellular Automation) model which tags the spatial attributes of cells through changes in their state during the evolution of CA and thus identifies the spatial growth mode of a settlement. The entrance area of the Caidian Botanical and Animal Garden is used a case study for the model. A design method is proposed which starts from the internal logics of spatial generation, explores possibility of spatial rules and realizes the quantitative analysis and dynamic control of the design process. Taking a top-down approach, the design method takes into account the site information, studies the spatial generation mechanism of settlements and further presents a engine for the generation of multiple layout proposals based on different rules. A optimal solution is acquired using GA (Genetic Algorithm) which generates a settlement spatial layout carrying site information and dynamically linked to the surround environment. The study aims to propose a design method to optimize the spatial layout of the complex settlement system based on parametric generation.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.847-852
• /
• 2009

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside feed-water heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of feedwater heaters may be affected by flow-accelerated corrosion. In this paper, to compare wall thinning range according to change entrance nozzle diameter and position with reference numerical analysis model's wall thinning range, various numerical analysis models applied. In case of changing diameter, four different diameter is applied. And a side of nozzle position, two different position-vertical type and parallel type-is applied. And then this paper describes operation of numerical analysis which is composed similar condition with real feed water heater. In conclusion, this study shows effective design for shall wall thinning by changing nozzle diameter and position.

• Journal of architectural history
• /
• v.16 no.4
• /
• pp.37-56
• /
• 2007

The '凸'-shaped, the '呂'-shaped and the hexagonal-shaped pit houses were excavated at the Youngdong area, some location along the upper the Imjin River and Han River between the Iron age and the kingdom of Hanseong Baekje. The aim of this study is to analyze various structural system and developement of the pit house with rectangular plan. It is considered a matter in all its aspects which are plan, scale, aspect, pillar holes, carbonized wood and several traces. These pit houses removes the pillar on the inside or it reduces to secure a wider space, it pursued the chamfered corner, the change of the front, the entrance fixed. Also these adopted diverse structural systems(the chuandou structure, the structural system of columns and beams and a bearing wall). But in the course of time, the Korean wooden architecture is developed gradually the structural system of columns and beams. It is presumed the result that overcome the limit with the close space and pursue the flowing space and compose a group of organizable buildings.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.489-492
• /
• 2006

In this study we collected and analyzed cases where typhoons damaged coastal structures in Korea in the past 6 years, and hydraulic model tests were conducted in 2D flume. 2 areas where damage was concentrated were selected from ports that had suffered damage. The selected area was Kyungsang-namdo, where there are a total of 26 national ports. Damage to these two areas was organized by wind direction of the typhoons and the direction of the entrance of the port, and destruction patterns were analyzed. 2D hydraulic model tests were conducted of Deabyeun port, one of the damaged areas. Results were as follows: 1. As a result of survey, ports that had entrances that were open to winddirection of typhoon (Anti-clockwise direction) tended to be damaged mare, whereas ports that blocked by island and ports that were not open to wind direction of typhoon were not damaged. 2. As a result of the tests, there was damage that occurred when using the section of designed section, whereas there was no damage when the TTP weight was increased.

• Journal of Forest and Environmental Science
• /
• v.29 no.4
• /
• pp.292-299
• /
• 2013

The study was undertaken to assess the tourist's carrying capacity and to explore ecotourism potential of Bangabandhu Sheikh Mujib Safari Park, the only safari park of Bangladesh. Carrying capacity was assessed both from physical and social aspect. On the other hand, 250 visitors were interviewed with semi structured questionnaire for ecotourism prospect evaluation along with some secondary data. The total daily-allowed visit was 17,300 with rotation coefficient of 3.46. Maximum daily average numbers of tourists were relatively below the physical carrying capacity of the Park (5,000). The social carrying capacity was 4.38 persons per day. As there are different categories of visitors, their choice of encounters and number of expected encounters also varied. Each year, the total tourist's number varied significantly ($p{\leq}0.05$). That proved the safari park had immense tourist prospect. 85 percent visitors were from lower and middle class family as entrance fees and other fees inside were very cheap in relation to other private amusement place. The ecological perspective of the park will remain unaltered if the carrying capacities of the area are followed with sustainability. Therefore, it is the proper time for taking appropriate decision.

• Journal of the Korean Home Economics Association
• /
• v.39 no.10
• /
• pp.169-186
• /
• 2001

The purpose of the study was to verify validity and reliability of performance assessment in home economics by applying performance assessment tools developed by Korean Curriculum Assessment Institute and by the researcher to a class of 17 high school female students in a rural area. For the purpose of this study, the research question was formulated and addressed:“How are the validity and reliability of performance assessment in home economics\ulcorner” The results of the study were as follows. 1. The results of testing validity a. Thirteen high school home economics teachers, whose average teaching years is ten years verified high validity in the contents of performance assessment. b. In the validity of the items that is verified being based on the scores of high school entrance examination of 2000 school year, the essay type showed its characteristics as performance assessment. c. The generalizability among assessment methods was not high. 2. The results of testing reliability Both Cronbach's $\alpha$, inter-item reliability of the assessment tools used in the research, and reliability among the raters were high. But reliability among the tasks was relatively low. This study proposed that the diverse performance methods, the increasing number of assessment, the explicit assessment criterion, and scoring criterion are needed to satisfying validity and reliability of performance assessment.

• Journal of Navigation and Port Research
• /
• v.38 no.6
• /
• pp.673-681
• /
• 2014

Due to the increased demand for safety and security requirements on the port infrastructure, the harbor tranquility is one of the important parameter in the mooring basin of harbor. It relates keenly to berthing/unberthing and cargo handling works but also it is an important indicator to get the minimum water area as the safe refuge. Hupo harbor is a national coastal harbor located in east coast of Korea and a development plan for a new marina near the entrance is being carried out including berth layouts, breakwater extensions, 300m marina berths, dredging and land reclamation works. The new plan will impact on calmness of the existing port. Therefore, it is necessary to analyze in complex the variation of wave height and direction caused by wave refraction, diffraction, shoaling and reflection from the incident waves from outside the harbor. In order to check the calmness inside a harbor, the numerical models are being used currently need fundamental reviews according to the difference of results which depend on their respective features. In this study, hence, it was introduced the validity of numerical models by comparing the computational results with the hydraulic model experiment. The current investigations contribute to the existing development recommendations and provide further solutions for port planning.

• Fire Science and Engineering
• /
• v.30 no.4
• /
• pp.14-19
• /
• 2016

When an interior fire occurs in an apartment building, pollution of the entrance area by fire smoke before an air fan operates makes the evacuation of people very difficult aswhen the fire doors are opened. Numerical simulations using Fire Dynamics Simulator were conducted to determine the impact of a sprinkler on the fire flow velocity. The fire flow velocity was compared depending on the presence of sprinklers and the sprayed droplet size. The configuration and actual dimensions of an apartment building were used in the numerical simulations. The simulation results showed that fire flow velocity becomes smaller when a sprinkler is installed. In addition, the smaller droplet size results in a smaller fire flow velocity because smaller droplets can be evaporated more easily.

• The Journal of the Korea Contents Association
• /
• v.10 no.12
• /
• pp.477-491
• /
• 2010

This paper aimed to understand current trends in online lectures for Korean SAT based on students' academic performances through a qualitative interview approach. In results, the highest academic performance group showed a good deal of interest and usage in online lectures. This group participants preferred private online lectures to public ones. However, the lowest academic group liked to use public online lectures. The middle academic groups who lived in an expensive area spent a lot of money for tutoring or attending private institutes rather than online lectures. Suggestions are: self-regulated learning is needed, public onilne lectures should have improved contents, and lastly, these online lectures are required to be connected with regular school curriculum.