• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.4
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• pp.455-478
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• 2019

In this paper, we conducted experimental investigation on the field applicability through the verification of reinforcement effect of the steel pipe reinforcement grouting using high strength steel pipe. SGT275 (formerly known as STK400) steel pipe is generally applied to the traditional steel pipe reinforcement grouting method. However, the analysis of tunnel collapse cases applying the steel pipe reinforcement grouting shows that there are cases where the excessive bending and breakage of steel pipe occur. One of the reasons causing these collapses is the lack of steel pipe stiffness responding to the loosening load of tunnels caused by excavation. The strength of steel pipe has increased due to the recent development of high strength steel pipe (SGT550). However, since research on the reinforcement method considering strength increase is insufficient, there is a need for research on this. Therefore, in this study, we conducted experiments on the tensile and bending strength based on various conditions between high strength steel pipe, and carried out basic research on effective field application depending on the strength difference of steel pipe through the conventional design method. In particular, we verified the reinforcement effect of high strength steel pipe through the measurement results of deformed shape and stress of steel pipe arising from excavation after constructing high strength steel pipe and general steel pipe at actual sites. The research results show that high strength steel pipe has excellent bending strength and the reinforcement effect of reinforced grouting. Further, it is expected that high strength steel pipe will have an arching effect thanks to strength increase.

• Korean Journal of Heritage: History & Science
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• v.43 no.1
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• pp.212-235
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• 2010

The purpose of this study is to examine the characteristics of the location and the spatial composition of Uireung that is located in Seokgwan-dong, Seongbuk-gu, Seoul, in order to understand the landscape architectural characteristics. The results are as follows. First, Uireung is 6.4km from Changdeokgung Palace and 5.5km from Heunginjimun Gate. It did not violate the distance standard (40km) for the royal tombs according to Joseon Dynasty Neung-won Myo-je. Second, Uireung is in harmony with the nature and shows the authoritative characteristics of the royal authority through the spatial composition and rank(Entrance Area, Ceremonial Area, Burial Area). Third, there are burial mound, stone sheep, stone tiger, stone table, stone watch pillars in the upper platform, and stone civil official, stone horse, stone lantern in the middle platform, and stone military official, stone horse in the lower platform, and T-shape shrine, worship road in the ceremonial area. There is no pond and a tomb keeper residence, but the position, size, and form can be approximated through historical research materials. There are a colony of pine trees around the burial mound and 64 species of trees such as pine tree, zelcova tree, and fir tree below the burial mound.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.27-35
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• 2019

The existing middle-long span railway bridge has been mainly applied to steel box girder bridges. However, the steel box girder bridges have disadvantages in securing the space under the bridge, and the main girder is made of a thin plate box shape, resulting in a ringing noise due to the vibration. Many complaints about noise have been raised. For this reason, there is a need for the development of long railway bridges that can replace steel box girder bridges. In this paper, the characteristics of the steel composite railway bridge currently developed were introduced and a time history analysis was conducted using MIDAS Civil reflecting the speed of KTX load for 40m and 50m bridges. In addition, from the analysis results, the dynamic behavior of target bridges were verified and it was examined whether they meet the dynamic performance criteria proposed in the railway design standards. As a result, all of the bridges under review satisfied the dynamic safety criteria, however, in case of 40m of span, the vertical acceleration value was very large. In order to solve this problem, authors proposed the improvement plan and corrected the cross section to confirm that the vertical acceleration decreased.

• Ecology and Resilient Infrastructure
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• v.6 no.2
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• pp.79-88
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• 2019

In order to study the water quality status and its causal environmental factors, the water quality variables of chemical oxygen demand (COD), chlorophyll a (Chl a), Total phosphorus (TP), and total nitrogen (TN), the hydrogeomorphologic variables of water level fluctuation, total water storage, dam elevation, watershed area, and shoreline development index, and the land cover variables of forest, agricultural area, and urbanized area in the watershed were investigated in total 73 reservoirs with various operational purposes, water level fluctuation and geographical distribution in South Korea. The water quality was more eutrophic in the reservoirs of the more urbanized and agricultural area in the watershed, the low altitude, the narrow water level fluctuation, the narrowed watershed area, and the more circular shape. In terms of the purposes of reservoir operation, the reservoirs for agricultural irrigation were more eutrophic than the reservoirs for flood control. The results of the variable selection and path analysis showed that COD determined by Chl a and TP was directly affected by water level fluctuation and the shoreline development of the reservoirs. TP was directly affected by the urbanized area of the watershed which was related to the elevation of the reservoir. TP was also influenced by the water level fluctuation and the shoreline development. In conclusion, the eutrophication of the reservoirs in Korea would be influenced by the land use of the watershed, hydrological and geographical characteristics of the reservoir, water level fluctuation by the anthropogenic management according to the reservoir operation purpose, and the location of the reservoirs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.93-113
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• 2019

The behavior of the 3 hinged precast arch structure was investigated by comparing field measurements with numerical analyses performed for precast lining arch structures, which are widely used for the open-cut tunnel. According to the field measurements, the maximum vertical displacement occurred at the crown with upward displacements during the backfilling up to the crown of the arch and downward displacements at the backfill height above the crown. The final crown displacement was 19 mm upward from the original position. The horizontal displacement at the sidewall, which had a maximum horizontal displacement, occurred inward of the arch when compacting the backfill up to the crown and returned to the original position after completing the backfill construction. According to the analysis of displacement measurements, economical design is expected to be possible for precast arch structures compared to rigid concrete structures due to ground-structure interactions. Duncan model gave good results for the estimation of displacements and deformed shape of the tunnel according to the numerical analyses comparing with field measurements. The earth pressure coefficients calculated from the numerical analyses were 0.4 and 0.7 for the left and the right side of the tunnel respectively, which are agreed well with the eccentric load acting on the tunnel due to topographical condition and actual field measurements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.597-605
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• 2019

IPM bridge is an integral bridge that can be applied from span 30.0m up to 120.0m, the shape conditions of IPM bridge is also applicable to the rahmen bridge. In this study, to perform the structural analysis of Rahmen bridge and IPM Bridge, the researchers compared the distribution types such as load, moment, and displacement of those bridges. Structural analysis was carried out on four span models ranging from single span bridges to four spans of 120.0 m, based on span length of 30.0 m. Structural analysis was carried out on those bridge with span 30.0m up to 120.0m. The conclusions drawn from this study are as follows. 1) The bending moments were calculated to be large for the Rahmen bridge, and the horizontal displacements were estimated to be large for the IPM bridge. 2) Since the bending moments are derived by the span length rather than the extension of the bridge, the permissible bending moment for the span length should be considered in the design. 3) The pile bent of the IPM bridge did not exceed the plastic moment of the steel pipe pile at 120.0m span, but because the horizontal displacement in the shrinkage direction is close to 25mm, the design considerations are needed. 4) In the actual design, it is important to ensure stability against member forces, so review of the negative moment is most important.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.534-544
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• 2019

Because the pile-bent of IPM Bridge is projected from the soil surface, excessive displacement of abutment can be induced. According to design guide of IPM Bridge, the shape of the bridges used in this study was applied to the maximum applicable 120.0m span, 30-degree for skew angle, and 10.0m for the protruded pile-bent height. The maximum displacement by the maximum span application condition of the IPM Bridge was calculated using this bridge model, and the safety of a horizontal displacement of the IPM Bridge was investigated based on the allowable displacement presented by Bozozuk. The maximum horizontal displacement of the IPM Bridge was calculated to be larger in the winter shrinkage condition than in the summer expansion condition, the horizontal displacements were more affected by the length of a bridge than by the skew angle. And the vertical displacement was not affected by the skew angle and length. As the span increases, the horizontal displacement increases significantly, the horizontal displacement at 120.0m span length was found to exceed the allowable displacement proposed by Bozozuk. However, the moment generated in the pile-bent did not exceed the plastic moment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.477-484
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• 2019

As the residence time in the vehicle increases, the passenger desires a pleasant and stable riding environment in addition to the high driving performance of the vehicle. The windshield defrosting performance is one of the performance requirements that is essential for driver's safe driving. In order to improve the defrosting performance of the windshield of a vehicle, relevant elements such as the shape of the defrost nozzle should be appropriately designed. In this paper, CFD based numerical analysis is conducted to improve defrost performance of small electric vehicles. The defrost performance analysis was performed by changing the angle of the defrost nozzle and the guide vane that spray hot air to the windshield of the vehicle. Numerical simulation results show that the defrosting performance is best when the defrost nozzle angle is $70^{\circ}$ and the guide vane installation angle is $60^{\circ}$. Based on the analytical results, the defrosting experiment was performed by fabricating the defrost nozzle and the guide vane. As a result of the experiment, it is confirmed that the frost of windshield is removed by 80% within 20 minutes, and it is judged that the defrost performance satisfying the FVMSS 103 specification is secured.

• Journal of the Korean Institute of Rural Architecture
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• v.21 no.2
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• pp.19-26
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• 2019

Pungsu theory is important one in the site selection and lay-out of traditional Korean village and house. In this aspect, Study with a view of Pungsu theory might be used as a proper method for understanding the traditional architecture in Korea. In this context, this study analyzes the Jeong, Dong-Ho's house which is designated no. 19 as an important folk cultural heritage, located in Jigok Ochu-gil 133-62, Godeok-myon, Yesan-gun, Chungnam province. The analysis of the site and space lay-out is carried out by Yong(Dragon), Hyoel(Auspicious Spot), Sa(Sands), Su(Water) aspects of the Pungsu(Fengshui) Hyungsei-ron. The house is depending upon soft dragon vein connecting with a earth type rear mountain. It looks southeast direction, Gonjwasonhyang(乾坐巽向). The hyeolseong(穴星) has classical venus shape, and there is no faults relatively. The Sasinsa condition is almost perfect that right blue dragon and left white tiger surround the hyeol with 3-4 layers and the facing mountain covers the front open area. The water flowing from inside of left and right mountain is joined in front of the house so it could stop flowing out of vital energy. Bibo forest(裨補樹) is placed properly to protect the easy disclose of water outlet. The house is well organized western house(西四宅) by analysis of Dongseosataek-ron(東西四宅論). Through the analysis, I found that the house has good Pungsu(Fengshui) environment fitted with Pungsu Hyungsei-ron. The house composed of small thatched roof is enclosed several times by low hills of back, left and right side. So it is believed that the site might be carefully evaluated by Yong, Hyoel, Sa, Su of Hyeongsei-ron for knowing whether the site condition could minimize the demage by strong winds and protect from the winter cold wind and secure water for drinking and farming and then selected. The method of Pungsu for evaluating the geographical condition of surrounding of a site is used as a traditional site analysis method for evaluating the suitability of long-term well and safe residence.

• Journal of the Korean Institute of Gas
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• v.23 no.1
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• pp.12-18
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• 2019

Exhaust gas recirculation method is widely used among various methods for reducing nitrogen oxides in automobile engines and incinerators. In the present study, the computational fluid dynamic analysis was accomplished to derive the optimal location of air nozzle exit position by changing its position in a venturi tube for the maximum flue gas recirculation effect. In addition, the flue gas recirculation characteristics with a cone at the exit of air nozzle was elucidated with flue gas recirculation flow rate ratio and mixed gas exit temperature. When the air nozzle exit position was changed from the start position (z = 0) to the end position (z = 0.6m) of the exhaust gas recirculation exit pipe, the change of streamline and temperature distribution in the venturi tube was observed. The exhaust gas recirculation flow rate and the average temperature at the mixed gas exit position was quantitatively compared. From the present study, the optimal location of air nozzle exit position for the maximum flue gas recirculation flow rate ratio and maximum mixed gas exit temperature is z = 0.15m (1/4L). In addition, when the cone is installed at the outlet of the air nozzle, the velocity of the air nozzle outlet is increased, the flue gas recirculation flow rate was increased by about 2 times of the flow rate without cone, and the mixed gas exit temperature is increased by $116^{\circ}C$.