• Journal of Ocean Engineering and Technology
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• v.30 no.2
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• pp.125-133
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• 2016

In this paper, we propose a vertical axis water turbine with dual blades. A parametric study was conducted using numerical analyses. First, a two-dimensional finite-volume analysis with a commercial code was used to find the pitch angle of the main blade under different tip speed ratio conditions. Second, we developed a potential-based panel method to find the best configuration of the inner blades. Experimental tests were conducted at the circulating water channel of Chungnam National University. Various configurations of the dual blades were considered, and their performances were comparatively investigated. The results showed that the turbine with movable dual blades produces a constant torque and tip speed ratio at various flow rates.

• Solar Energy
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• v.12 no.3
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• pp.84-93
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• 1992

Solar assisted heat pump with freon circulating system has been developed. Revising the cool chamber(flower storage) with the solar thermal hot water producing system, the more amount of hot water can be produced, which can be even used for room panel heating. The compressor was cooled by water jaket instead of air cooled so that the system energy efficiency was improved quite well.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.60-65
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• 2000

The virtual mass of net is an important parameter in the analysis and control of net movement in the water. This experiment was performed with the purpose of getting a relation on the quantity of netting and virtual mass of trawl nets using the circulating water channel that can control flow speed. Twelve types of conical nets were examined. Resistance of the conical net at the steady and acceleration state was recorded as text on the personal computer through the tension meter and current meter. The results were obtained as follows ;1. Resistance(R) of the conical net is proportional to the degree of attack angle in the sam e amount of twine material.2. Coefficient of the resistance(Cd)could be defined by the following regression model as a function of Reynolds Number(Re). Cd=0.039Re-0.14743. Resistance(R) is proportional to TSA(Twine surface area) and defined as follows; R=21.398TSA-0.12194. Coefficient of virtual mass(CM) could be calculated by the following first order regression model. CM=37.557U-8.96845. Virtual mass is directly proportional to Volume of net(V) or d/l.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.11
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• pp.739-745
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• 2008

This paper presents the measurement of ground thermal conductivity and the characteristics of ground thermal diffusion by a ground heat exchanger(GHE). A borehole is installed to a depth of 175 m with a diameter of 150 mm. To analyze the thermal diffusion property of the GHE, thermocouples are installed under the ground near the GHE. The outdoor temperature, the ground temperature, and the water temperature of the GHE are monitored for evaluating the characteristics of ground thermal diffusion. The ground thermal conductivity is evaluated by the in-situ thermal response tester and the line source model. It is found to be 3.08 W/$m^{\circ}C$ in this study. The ground temperature is greatly dependent on the outdoor temperature from the ground surface to 2.5 m in depth and is stable below 10 m in depth. The surface temperature of the GHE varies as a function of the temperature of circulating water. But the ground temperature at 1.5 m far from the GHE is not changed in accordance with the temperature of circulating water.

• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.4
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• pp.193-200
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• 2015

Background: During head and neck surgery including orthognathic surgery, mild intraoperative hypothermia occurs frequently. Hypothermia is associated with postanesthetic shivering, which may increase the risk of other postoperative complications. To improve intraoperative thermoregulation, devices such as forced-air warming blankets can be applied. This study aimed to evaluate the effect of supplemental forced-air warming blankets in preventing postanesthetic shivering. Methods: This retrospective study included 113 patients who underwent orthognathic surgery between March and September 2015. According to the active warming method utilized during surgery, patients were divided into two groups: Group W (n = 55), circulating-water mattress; and Group F (n = 58), circulating-water mattress and forced-air warming blanket. Surgical notes and anesthesia and recovery room records were evaluated. Results: Initial axillary temperatures did not significantly differ between groups (Group $W=35.9{\pm}0.7^{\circ}C$, Group $F=35.8{\pm}0.6^{\circ}C$). However, at the end of surgery, the temperatures in Group W were significantly lower than those in Group F ($35.2{\pm}0.5^{\circ}C$ and $36.2{\pm}0.5^{\circ}C$, respectively, P = 0.04). The average body temperatures in Groups W and F were, respectively, $35.9{\pm}0.5^{\circ}C$ and $36.2{\pm}0.5^{\circ}C$ (P = 0.0001). In Group W, 24 patients (43.6%) experienced postanesthetic shivering, while in Group F, only 12 (20.7%) patients required treatment for postanesthetic shivering (P = 0.009, odds ratio = 0.333, 95% confidence interval: 0.147-0.772). Conclusions: Additional use of forced-air warming blankets in orthognathic surgery was superior in maintaining normothermia and reduced the incidence of postanesthetic shivering.

• Korean Journal of Veterinary Research
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• v.39 no.1
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• pp.177-188
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• 1999

The studies were carried out to investigate the effect of recovery in rewarming using the esophageal thermal tube in the deep hypothermia($25{\pm}1^{\circ}C$ ; rectal temp) in rabbits. Fifteen rabbits were divided into control group(n=6), peritoneal dialysis group(n=5) irrigated with dialysate at $42{\pm}1^{\circ}C$, and esophageal rewarming group(n=4) perfused with circulating water at $38{\pm}1^{\circ}C$. Rewarming of the rabbits was performed for 5 hours. MAP, HR, RR, esophageal temp, rectal temp, pH, $pCO_2$, $pO_2$, $Na^+$, and $K^+$ were observed. The results obtained in these experiments were summarized as follows : Esophageal rewarming group($38{\pm}1^{\circ}C$) had more effect on esophageal temperature than other groups. Peritoneal dialysis group($42{\pm}1^{\circ}C$) had more effect on rectal temperature and $pO_2$ than other groups. The both groups also had more effects on MAP, HR, RR, and $pCO_2$ than control group. Three groups had no significant effect on pH, $Na^+$, and $K^+$. In conclusion, we found that the simple, safe, and non-invasive esophageal rewarming method had an effect on the treatment of profound hypothermia as well as the peritoneal dialysis method in spite of the temperature difference between the dialysate and the circulating water, and the circulating water at $38{\pm}1^{\circ}C$ for esophageal rewarming also had an effect on the recovery of deep hypothermia.

• Solar Energy
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• v.8 no.2
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• pp.46-56
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• 1988

This investigation concerns thermal stratification of the water due to the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the water in the test tank (1m wide, 1m high, 2.1m long) and the temperature of the inflow water into the tank; flow rate of circulating water and height of the sink diffuser in the test tank. The additional objectives was to observe a stratification phenomena near an interface by measuring the velosities and the temperature difference and investigate an availabilities of the better effective hot water through establishing thermocline near an interface around the bottom of the tank. Following results were obtained through the experiments. 1. When the flow rate was constant and the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the flow in the test tank and the temperature of the inflow water increased by 5.6, 9.5, 13.5($^{\circ}C$), obtained the better effective advantage of hot water and the stress near an interface increased gradually. 2. When the ${\Delta}T=T_{\infty}-T_i$ was constant and flow rate increased by 4.0, 4.8, 6.4, 8.0 (LPM), obtained the better effective advent age of hot water and the mean stress near an interface increased gradually. 3. When the height of the sink diffuser was 25cm from tank bottom in comparison with 50cm, obtained the better effective advantage of hot water and the mean stress near an interface increased.

• Korean Institute of Interior Design Journal
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• v.21 no.5
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• pp.355-362
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• 2012

Water Culture Pavilion was constructed as a part of dam construction and Four-major rivers restoration projects, which have the purpose to prevent damage of natural disaster, localized heavy rain and drought, and has several functions; promotion, education and region culture community. Exhibition space in this culture pavilion should have the excellent connection of various media, contents, and exhibition space because of limited space. The purpose of this study is to analyze flows, continuation and connection of exhibit space with the perspectives of the attribute of water and to suggest various content things, technical, spatial types. This study targets Four-major rivers Water Culture Pavilion in Korea and suggests exhibition presentation methods as analyzing contents, media and constituent of exhibition space for each pavilion exhibition. The result of this study is as follows : First, the circulation is common expressed attribute of water in these four water culture pavilion. The reason is that there is a connection between Four-major rivers restoration projects and the physical attribute of water circulating the steps of evaporation, condensation and precipitation. Second, each pavilion presents circulative solid exhibit, circulative background exhibit, circulative reflective exhibit based on circulation. These three types of exhibition is related the floor separation. Third, each pavilion exhibit zone shows the most circulation, solid, background, reflexibility through educational contents and promoting contents by using graphic, video, sound media.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.7
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• pp.74-80
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• 2020

The ocher jjimjilbang for a single-person household that will be studied in this study is 2.1 ㎡ in size, and this study was conducted to implement well-being room heating that is beneficial to health by supplying radiant heat provided by hot water during room heating by embedding hot water panels in the walls of the ocher jjimjilbang to configure a hot water circulating system. In addition, the ocher bed and the ocher walls, which have been verified through many study findings and reference materials, were constructed so that the living life with a bed and the ocher jjimjilbang would be implemented simultaneously. As the mass flow rate of the hot water increased, the magnitude of the wall temperature rise thanks to the hot water increased, and as the flow rate of the hot water increased, the transfer rate of the heat transferred from the wall of the ocher jjimjilbang to the air inside the wall of the ocher jjimjilbang increased.

• Environmental Engineering Research
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• v.24 no.4
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• pp.582-590
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• 2019

Currently, the waterfront facility was constructed in New Songdo City, South Korea. It has the various water leisure areas and especially an artificial urban canal with filtered seawater by re-circulating flow system. However, due to excessive amount of nutrients from seawater combined with complicated geometry, it is highly vulnerable to deterioration of water quality. In this study, flow characteristics and pollutant transport were analyzed with comprehensive numerical models, MIKE 3 FM and ECO-lab. Based on these numerical results, notable sampling points were selected for field measurements and comparison between modeling and measured results were conducted. In addition, the integrated water quality evaluation index, Water Quality Index was applied to analyze various water quality issues. We also set up scenarios to control the two kinds of water quality factors, dissolved oxygen (DO), and total phosphorus (TP). As a result, the effect of 20% reduction of TP was less than 10% and it was almost ineffective for a year but it was reduced by up to 40% in case of scenario which DO is increased by 20%. Therefore, it was recommended to control the DO concentration, usually by applying re-aeration facility, rather than TP in artificial urban canal with seawater.