• Journal of Korea Water Resources Association
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• 제52권5호
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• pp.313-323
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• 2019

Deep Tunnel system is a large-scale urban flood control facility installed underground in order to reinforce the lack of drainage systems in developed cities. In a structure like a deep tunnel system, the undular bore generated in the downstream causes a problem in the hydraulic stability of the tunnel. In this study, to investigate the influence of the undular bore on the hydraulic stability at the "Shinwol rainwater storage and drainage system", under construction for the first time in the country, a hydraulic model experiment was conducted on various flooding inflow scenarios. As a result of the hydraulic model experiment carried out in this study, the undular bore generated downstream is trapped in the pipe while moving to upstream, pushes the compressed air. It is judged that overflow occurred by choking the vertical drop shaft in the process when this compressed air is being exhaust through the upstream vertical drop shaft and blocking flood inflow. In addition, the analysis of velocity of undular bore shows that the undular bore transfers energy, and at this time, the pressure rose in the pipe and the velocity increment occurred of the undular bore. Further studies are needed to predict the size and velocity of undular bore, which plays an important role in the hydraulic stability of the tunnel in the deep tunnel system.

• Journal of the Korea Institute of Building Construction
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• 제19권2호
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• pp.175-184
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• 2019

This paper presents a modeling prototype that optimizes construction processes implementing information communication technology (ICT). Using "IAMB", each and every actual steps of the construction process may be defined visually and explicitly by elaborating ICT to improve productivity and management efficiency. It contributes to identify the features on what parts of construction task are covered by ICT, and the effects of ICT on process performance. After analyzing 10 real project cases, ICT application types are classified into four categories according to ICT type, job functions that ICT applied, and the project phase in which ICT used. As a reuslt, it was confirmed that the positive outcomes on the construction process were beneficial to mostly the general contractors and mainly obtained by automated information processing, external consignment and consistent information use. Negative effects, which were occurred by mainly manual manipulation and duplication of information handling, were accrued to general contractors minimally, but to subcontractors maximally. Expert focus group commends that several important issues should be considered when implementing ICT.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제19권12호
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• pp.523-531
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• 2018

The purpose of this paper is to derive priorities and implications for the organic resource conservation policy in the livestock sector. We conducted a survey on the importance-performance of the organic waste resource reclamation of livestock sector using a 5-point Likert scale. The importance average for the resource recycling of livestock organic waste was 3.63 and the average of performance was 3.04. As a result of the IPA on livestock manure recycling measures, it is necessary to improve feed quality, establish a local recycling system, increase demand for compost and liquid, enhance customer linkages, and develop cost reduction technologies. It requires intensive support for promoting the spread of odor reduction technologies and integrated management of biomass. It is necessary to introduce mid- and long-term measures such as the revival of feed in tariff, promote by-product feeding, establish solid fuel process management standards, create hygiene safety standards, develop eco-beads and promotion of feed conversion. It is required to strengthen support for the development of odor reduction technologies and prepare consultative organizations among related departments, develop eco-friendly solid fuel technology, and support policies for renewable energy certification.

• Journal of The Korean Society of Emergency Medicine
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• 제29권6호
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• pp.649-655
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• 2018

Objective: This paper reports the possibility of using of a locking horizontal mattress suture technique in repairing lacerations that are difficult to suture with staples. Methods: Data were collected retrospectively over a 6-month period regarding the routine repair of scalp lacerations: those in areas injured by a high energy blunt mechanism, continued to bleed after pressure, nonlinear or damaged skin repaired with a locking horizontal mattress technique, and simple interrupted technique. The effects of the two techniques used to repair scalp lacerations on wound healing, complication rate, and patient satisfaction were examined. The categorical variables are expressed as the number and percent. A Mann-Whitney-Wilcoxon test was used for statistical analysis. A P-value less than 0.05 was considered significant. Results: Thirty-seven consecutive patients with scalp lacerations presented for care. Wound closure was accomplished with the locking horizontal mattress sutures in 40.5% (n=15) (median length, 5.0 cm; interquartile range [IQR], 4.0-7.0 cm). Simple interrupted sutures (median length, 4 cm; IQR, 3.0-5.0 cm) were used in 59.5% (n=22) (P=0.015). The frequency of additional bandage compression (P=0.008), frequency of exudative hemorrhage (P=0.018), and suture mark frequency at suture removal (P=0.047) were significantly lower in the locking horizontal mattress group. Conclusion: The locking horizontal mattress suture, which has the advantage of a horizontal mattress suture, may be one of the ways that can be used alternatively to treat scalp lacerations that difficult to suture with staples.

• Nutrition Research and Practice
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• 제15권5호
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• pp.604-612
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• 2021

BACKGROUND/OBJECTIVES: We aimed to investigate the association of waist circumference (WC) with body composition among individuals with a normal body mass index (BMI) to distinguish muscle and fat mass, as both affect health differently. SUBJECTS/METHODS: We analyzed dual-energy X-ray absorptiometry data (derived from the Korean National Health and Nutrition Survey, which includes information on fat and lean mass) of 7,493 adults with a normal BMI. Subjects were categorized into four groups of increasing WC. The fourth group was defined as being centrally obese. Each number of subjects are as follows: 1,870, 695, 231, and 39 among men and 3,054, 1,100, 406, and 98 among women. We conducted a sex-stratified linear regression analysis of body composition according to WC group after adjustments for covariates. RESULTS: We observed a positive association of body fat with increasing WC in both men and women (all P for trend: < 0.001). The adjusted mean values for percent body fat with 95% confidence intervals (CIs) according to the four WC groups in ascending order were 17.8 (17.5-18.3), 21.0 (20.6-21.5), 22.1 (21.5-22.8), and 25.1 (24.2-26.1) in men and 29.7 (29.4-30.0), 32.0 (31.6-32.3), 32.9 (32.4-33.4), and 34.7 (33.2-36.1) in women. However, there was an inverted J-shaped association between muscle mass and WC. The fourth group had a higher percent body fat and lower muscle mass than other groups. The adjusted mean values for appendicular skeletal muscle mass index (kg/m²) with 95% CIs according to the four WC groups in ascending order were 7.55 (7.51-7.59), 7.62 (7.56-7.68), 7.65 (7.56-7.74), and 7.22 (7.04-7.41) in men and 5.83 (5.80-5.85), 5.96 (5.92-6.00), 6.03 (5.96-6.10), and 5.88 (5.73-6.03). CONCLUSIONS: There was a positive association between body fat and WC among individuals with normal BMI; conversely there was an inverted J-shaped association between lean body mass and WC. Our findings support the WC measurement should be included in obesity evaluations for adults with a normal BMI.

• Journal of the Korea Organic Resources Recycling Association
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• 제29권3호
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• pp.27-33
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• 2021

CO I gene sequence analysis was applied to earthworms that had been used as test animals in toxicity test in Institute of Kyeongbook Agrochemicals and earthworms used as vermicomposting agents in the farm of Youngdong province to identify their species names. In terms of molecular species, the former was identified as Eisenia fetida and the latter was Eisenia andrei. Cocoons produced from Eisenia fetida was more than those from Eisenia andrei. And No. of adults developed from eggs of Eisenia fetida was more or less higher than those developed from eggs of Eisenia andrei. These results were contradictory to previous reports on two Eisenia spp.. When Eisenia fetida was crossed with Eisenia andrei, hybridized eggs were produced and adults were developed from those eggs, but cocoons and adults were much less than those from non-crossed Eisenia fetida or Eisenia andrei. This indicated that two Eisenia spp. were not distinctly different biological species because there was no complete 'reproductive isolation' between Eisenia fetida and Eisenia andrei. However, this also meant that Eisenia fetida and Eisenia andrei had already been on the tract of speciation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제31권4호
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• pp.166-173
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• 2021

The rutile phase of TiO₂ forms a stable phase at high temperatures compared to anatase phase, but the stable temperature range of anatase changes depending on the synthesis conditions. In this study, nano-sized TiO₂ was synthesized by the Sol-gel method using TiOSO₄ and a mixed solvent of ethanol and distilled water, and the phase change of anatase and rutile according to pH and heat treatment temperature was investigated. Changes in the ratio of anatase and rutile were observed by changing the pH (3, 5, 7, 9) and heat treatment temperature (500, 600, 700, 800, 900℃) conditions of the prepared TiO₂. As a result of observing these changes through XRD and FE-SEM analysis, anatase TiO₂ at 500℃ and rutile TiO₂ at 900℃ were observed. According to the pH, at these intermediate temperatures of 600, 700 and 800℃, the ratio of anatase and rutile changes. At 700℃, it was concluded that pH = 3~5 had a larger ratio of anatase TiO₂, and pH = 7~9 had a larger ratio of rutile TiO₂.

• Journal of the Korean Society of Propulsion Engineers
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• 제25권1호
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• pp.1-11
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• 2021

POGO is a dynamic axial instability phenomenon that occurs in liquid-propelled rockets. As the natural frequencies of the fuselage and those of the propellant supply system become closer, the entire system will become unstable. To predict POGO, the propellant (oxidant and fuel) tank in the first stage is modeled as a shell element, and the remaining components, the engine and the upper part, are modeled as mass-spring, and structural analysis is performed. The transmission line model is used to predict the pressure and flow perturbation of the propellant supply system. In this paper, the closed-loop transfer function is constructed by integrating the fuselage structure and fluid modeling as described above. The pogo suppressor consists of a branch pipe and an accumulator that absorbs pressure fluctuations in a passive manner and is located in the middle of the propellant supply system. The design parameters for its design optimization to suppress the decay phenomenon are set as the diameter, length of the branch pipe, and accumulator. Multiple-objective function optimization is performed by setting the energy minimization of the closed loop transfer function in terms of to the mass of the pogo suppressor and that of the propellant as the objective function.

• Journal of the Korea Institute of Building Construction
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• 제21권5호
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• pp.483-493
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• 2021

Urban overcrowding has created an explosive supply and demand for high-rise buildings. High-rise buildings are contributing to enhancing the image of the city by serving as focal points, but due to the stack effect, malfunction of elevator doors, difficulties in opening and closing the doors and windows of the outer wall, smoke and odors spreading to the upper floors, noise, energy loss, fire and pollutants have been causing various unexpected problems such as rapid spread of fire. This study classified high-rise buildings according to their vertical zoning, analyzed the causes of and solutions to the stack effect, and derived design and construction methods. Through the initial plan to block the outside air and securing airtightness through precise construction, we sought ways to secure the airtightness inside and outside the building by actively blocking the airflow from the lower floors. In addition, the facility solution can be a measure to reduce the specific phenomena caused by the stack effect, but it should only be applied to the minimum extent because the potential for secondary damage is high. This study emphasized the need for systematic stack effect management by suggesting design and construction measures for each vertical zoning of the causes and countermeasures of the stack effect. It is expected that this study will be helpful not only for design and construction, but also for building maintenance.

• Journal of Bio-Environment Control
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• 제28권4호
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• pp.388-395
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• 2019

The purpose of this study is to suggest structural model and analyze design factors for the development of small greenhouse standardization model. The average dimensions of small greenhouse desired by urban farmers were 3.3m in width, 1.9m in eaves height, 2.7m in ridge height, 5.7m in length. The cladding materials for small greenhouse were preferred to glass, PC board and plastic film, framework to aluminum alloy and steel, and heating method in electrical energy. In addition, it was analyzed that small greenhouses need to develop structural model by dividing them into entry-level type and high-level type. The roof type that was used for entry-level type was arch shape, framework was steel pipe, cladding material was plastic film. On the other hand, high-level type was used in even span or dutch light type, framework with square hollow steel, cladding materials with glass or PC board. In consideration of these findings and practicality, this study developed four types of small greenhouses. The width, eaves height, ridges height, and length of the small greenhouses of even span type, which were covered with 5mm thick glass and 6mm thick PC board were 3m, 2.2m, 2.9m, and 6m, respectively. The small greenhouse of dutch light type covered with 5mm thick glass was designed with 3.8m in with, 2.2m in eaves height, 2.9m in ridges height, and 6m in length. The width, eaves height, ridges height, and length of the arch shape small greenhouse covered with a 0.15mm PO film were 3m, 1.5m, 2.8m, and 6m, respectively.