• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.523-530
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• 2022

The problem in the construction of seawall reinforcing the seawall where there is seawater flow is the outflow of materials. Gravity-type pouring of concrete is difficult to fill the voids smoothly, and the cement of concrete that has not hardened is likely to be dispersed in seawater. This phenomenon not only reduces the reliability of quality after concrete hardening, but can also adversely affect the surrounding environment. Therefore, there is a need for a gel-like injection material that can be injected, In this study, the initial strength and durability improvement effect of seawater immersion were evaluated by using electrofurnace reduction slag and blast furnace slag with acute properties. As a result of the experiment, it was possible to prepare a gel-like injection material having flowability through reaction with silica-based chemical liquid. The flowability of the gel is 105~143 mm depending on the formulation, and the on-site simulation test can fill the voids without external leakage, confirming its on-site applicability.

• Geomechanics and Engineering
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• v.30 no.6
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• pp.525-538
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• 2022

This paper presents a more general model for T-shaped combined footings that support two columns aligned on a longitudinal axis and each column provides an axial load and two orthogonal moments. This model can be applied to the following conditions: (1) without restrictions on its sides, (2) a restricted side and (3) two opposite sides restricted. This model considers the linear soil pressure. The recently published works have been developed for a restricted side and for two opposite sides restricted by Luévanos-Rojas et al. (2018a, b). The current model considers the uniform pressure distribution because the position of the resultant force coincides with the center of gravity of the surface of the footing in contact with the soil in direction of the longitudinal axis where the columns are located. This paper shows three numerical examples. Example 1 is for a T-shaped combined footing with a limited side (one column is located on the property boundary). Example 2 is for a T-shaped combined footing with two limited opposite sides (the two columns are located on the property boundary). Example 3 is for a T-shaped combined footing with two limited opposite sides, one column is located in the center of the width of the upper flange (b₁/2=L₁), and other column is located at a distance half the width of the strip from the free end of the footing (b₂/2=b-L₁-L). The main advantage of this work over other works is that this model can be applied to T-shaped combined footings without restrictions on its sides, a restricted side and two opposite sides restricted. It also shows the deficiencies of the current model over the new model.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.391-395
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• 2009

For the conversion of domestic waste-wood into energy, a fixed bed gasifier ($0.9 m{\times}2.4 m$) having the capacity of 2 ton/day was designed and constructed. The dual knife valve was used to feed waste-wood of which size was 3~5 cm and a rotary stoker system was installed in the bottom of gasifier. The pilot gasification system consisted of feeding system, fixed bed gasifier, gravity fine particle collector, heat exchanger for syngas cooling, ID fan, and cooling tower. The operation temperatures of gasifier were $700{\sim}1000^{\circ}C$ and the concentrations of syngas were CO: 25~40 vol%, $H_2$: 7~12 vol%, $CH_4$: 2~4 vol%, $CO_2$: 12~24 vol%. The calorific value of syngas was $1100{\sim}1500kcal/Nm^3$ and was enough to be applied in the industrial combustor. Also the gas engine was operated by using syngas from biomass gasifier and produced 1~4 kW of power.

• Korean Journal of Heritage: History & Science
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• v.38
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• pp.329-358
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• 2005

The Three storied Stone pagoda in Gameunsa Temple site, one of the early staged stone pagodas, has been known as a standard for Silla stone pagodas. A stone pagoda is not only a stone art work and but also a stone structure. Most studies and investigation of the stone pagoda has done mainly based on style and chronological research according to an art historical view. However, there is not an attempt to research the stone pagoda as a stone architecture. Most Korean experts at the stone pagoda has art history in their background. Engineers who can understand the structure of the stone pagoda are very limited. More architectural and engineering approach is need to research not only art historial understanding but also safety as a structure. We can find many technical know-how from our ancestors who made stone pagodas. 1. To reduce any deformation such as relaxation and sinking of BuJae which is caused by a heavy load, the BuJae (consist of a foundation stone and lower stereobates) should be enlarged. 2. A special construction method for connection between Myonsuk and Tangjoo was invented. This unique method is not used any longer after the Three storied Stone pagoda in Gameunsa Temple site. 3. The upper BuJae and the lower BuJae are missed each other by making a difference of Okgaesuk and Okgaebatchim in size. It is done for a distribution of perpendicular load and a prevention for relaxation of BuJae. 4. The center of gravity in the BuJae is located to the center of the stone pagoda by trimming the upper surface of the Okgaebatchim into a convex shape. The man who made stone pagodas had excellent knowledge on the engineering and techniques to understand the structure of the stone pagodas. We can confirm it as follows: the enlarged BuJae, dislocated connection between upper Bujae and lower BuJae, and moving the center of gravity close to the center of the stone pagoda.

• Journal of the Korean earth science society
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• v.25 no.6
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• pp.418-427
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• 2004

Recently, urban planning with consideration of urban climate, represented by the concept of urban ventilation lane is widely practiced in many countries. The concept of urban ventilation lane is mainly aimed to improve the thermal comfort within urban area in summer season. It has also the aim to reduce the urban air pollution by natural cold air drainage flows which are to be intensified by a suitable alignment of buildings as well as use zonings based on scientific reasons. In this study, the prevailing wind ventilation lane of a local wind circulation and around Daegu for a typical summer days was investigated by using a numerical simulation. The transport of air pollutants by the local circulation winds was also investigated by using the numerical simulation model, the RAMS (Reasonal Atmospheric Model System).The domain of interest is the vicinity of Daegu metropolitan city (about 900 km2). The horizontal scale of the area is about 30 km. The simulations were conducted under a late spring synoptic condition with weak gradient wind and almost clear sky. From the numerical experiment, the following three conclusions were obtained: (1) The major wind passages of the local circulation wind generated by radiative cooling over the representative mountains of Daegu (Mt. Palgong and Mt. Ap) were found. The winds blow down along the valley axis over the eastern part of Daegu as a gravity flow during nighttime. (2) At the flatland, the winds blow toward the western part of Daegu through the city center. (3) As the results, the air pollutants were transported toward the western part of Daegu by the winds during nighttime.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.177-184
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• 2003

Numerical simulation on marine wind and sea surface elevation was carried out using both three-dimensional hydrostatic and non-hydrostatic models and a simple oceanic model from 0900 LST, August 13 to 0900 LST, August 15, 1995. As daytime easterly meso-scale sea-breeze from the eastern sea penetrates Kangnung city in the center part as basin and goes up along the slope of Mt. Taegullyang in the west, it confronts synoptic-scale westerly wind blowing over the top of the mountain at the mid of the eastern slope and then the resultant wind produces an upper level westerly return flow toward the East Sea. In a narrow band of weak surface wind within 10km of the coastal sea, wind stress is generally small, less than l${\times}$10E-2 Pa and it reaches 2 ${\times}$ 10E-2 Pa to the 35 km. Positive wind stress curl of 15 $\times$ 10E-5Pa $m^{-1}$ still exists in the same band and corresponds to the ascent of 70 em from the sea level. This is due to the generation of northerly wind driven current with a speed of 11 m $S^{-1}$ along the coast under the influence of south-easterly wind and makes an intrusion of warm waters from the southern sea into the northern coast, such as the East Korea Warm Current. On the other hand, even if nighttime downslope windstorm of 14m/s associated with both mountain wind and land-breeze produces the development of internal gravity waves with a hydraulic jump motion of air near the coastal inland surface, the surface wind in the coastal sea is relatively moderate south-westerly wind, resulting in moderate wind stress. Negative wind stress curl in the coast causes the subsidence of the sea surface of 15 em along the coast and south-westerly coastal surface wind drives alongshore south-easterly wind driven current, opposite to the daytime one. Then, it causes the intrusion of cold waters like the North Korea Cold Current in the northern coastal sea into the narrow band of the southern coastal sea. However, the band of positive wind stress curl at the distance of 30km away from the coast toward further offshore area can also cause the uprising of sea waters and the intrusion of warm waters from the southern sea toward the northern sea (northerly wind driven current), resulting in a counter-clockwise wind driven current. These clockwise and counter-clockwise currents much induce the formation of low clouds containing fog and drizzle in the coastal region.

• The Korean Journal of Rehabilitation Nursing
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• v.2 no.1
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• pp.72-84
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• 1999

The purpose of this study was to identify the effectiveness of bladder training on self voiding after removal of catheter in female patients with craniotomy, finally to develop a bladder rehabilitation program for cognitive impaired patients. Nonequivalent control group posttest design was used. The population of this study consisted of 34 hospitalized neurosurgical patients, all patients have been received craniotomy. 17 patients were assigned to the experimental group and another 17 patients to the control group. The homogeneity of general characteristics of the subjects was no significant difference. Bladder training program consisted of pre-training education, the bladder training, positive verbal reinforcement. The experimental group has been received bladder training and the control group has been received gravity drainage. The dependent variable, the frequency of voiding trial untill self voiding achieves, the frequency of urinary retention, the amount of residual urine, the occurrence, of urinary incontinence, were measured during 3 days after catheter removed. The data analyzed with SPSSWIN ; frequency, percentage, t-test and $X^2$-test were used to analyze homogeneity of general characteristics of subjects between the experimental and the control group. T-test, Mann-Whitney U test, and $X^2$-test were used to determine the effect of bladder training. The result of the study were as follows : There was significant difference in the frequency of voiding trial untill self voiding achieves between the experimental group and the control group. There was no significant difference in the frequency of urinary retention between the experimental group and the control group. There was no significant difference in the amount of residual urine between the experimental group and the control group. However, there was significant difference in the amount of residual urine in urinary retention patients. There was significant difference in the occurrence of urinary incontinence between the experimental group and the control group. In conclusion, bladder training program as a nursing intervention was effective in conclusion, bladder self voiding ability after removal of catheter for craniotomy patients. Therefore, it is recommended to use the bladder training program clinically for the bladder management of cognitive impaired patients.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.2
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• pp.137-143
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• 2016

The sedimentary environment and sediment were surveyed at the West-Northern site of Chagwi-do nearby Jeju Island for the design of the embedded suction anchor system of 10 MW-class floating wave-offshore wind hybrid power generation system. According to the classification scheme of Chough et al.[2002], the echo type of the seismic profiles using the chirp III was classified. As a results, the center and west-northern area of survey site were proved to be type I-3 where subbottom layer with thickness 5~15 m exists under the flat seafloor. On the other hands, the east-southern area were regarded to be type I-1, I-2 and III-1 where seafloor reflection is much stronger than type I-3. Also, the physical tests (unit weight, moisture content, grain size, liquid limit, specific gravity) were performed with samples taken from 8 fixed locations. It is found that the sand (SP), the sand blended with silt (SM) and the mixture of SP-SM are distributed uniformly on the survey area.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.169-177
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• 2017

Recently, as the size of transportation vessels has increased, there is a growing need for securing the front-water depths of existing port facilities. The method of deepening front-water depth is securing the depth of the port facility, and it is reinforced by grouting after excavating the rubble-mound to the required depth. The purpose of this study is to investigate the reinforcing performance and filling performance of thixotropic grout as a grouting material for reinforcing rubble-mound. Compressive strength tests were carried out for two types of thixotropic grout, and 5 specimens with a diameter of 400 mm and a height of 530 mm were manufactured and evaluated for filling performance. The required strength of reinforced rubble-mound required to ensure the safety of the structure is 6 MPa. All the thixotropic grouts used in this study were found to satisfy the required strength over 9 MPa at 7 days of age. As a result of visual observation of filling state of the filling performance test specimens, it was confirmed that the thixotropic grout was well filled up to the desired fillet height.

• Journal of the Korean Wood Science and Technology
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• v.30 no.4
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• pp.87-95
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• 2002

Three different species of green and air-dried Korean bamboos were carbonized by using three different types of kilns designated as special (800~1000℃), improved (600~700℃) and simple kiln (400~500℃), and the bamboo vinegars obtained from the carbonization processes were characterized. In the case of the special kiln, most of the bamboo vinegars obtained at the first recovery stage showed high values of specific gravity and also in content of organic acid and water-soluble tar. The bamboo vinegars obtained from the improved kiln showed various physical properties depending on their species. In the case of simple kiln, the bamboo vinegars obtained from air-dried bamboos and at temperatures below 80℃, showed a higher specific gravity and more water-soluble tar as well as total organic components than those obtained at 80~150℃. A good linear relationship (correlation coefficient of ca. 0.90) was obtained between the specific gravities and the sum of organic acids and water-soluble tars. Therefore, this correlation coefficient might be a good index to determine the quality of bamboo vinegars. The major chemical constituents of the bamboo vinegars were acetic acid and considerable amounts of phenols: guaiacol, ethyl guaiacol, syringol, and methyl syringol.