• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.13-18
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• 2023

Cast-in-place concrete lining is commonly used in tunnel lining, but cast-in-place concrete lining has problems with construction and quality control. Precast segment lining is being used to solve these problems. In general, precast segment lining is known to have improved durability and easy maintenance such as rehabilitation of structures. This study compared the durability of 22 tunnel linings constructed with precast segments or cast-in-place reinforced concrete.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.49.1-49.9
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• 2016

Background: The aim of this report is to present a new reference for aesthetic mandible surgery using three-dimensional cone-beam computed tomography-based treatment planning for orthognathic surgery which can be implemented in surgical planning and perioperative procedure. Methods: To make an objective standard for evaluating aesthetic mandibular outline, we make an aesthetic scoring criteria with consideration of asymmetry, broad mandibular border line, and prominent mandibular angle. Two maxillofacial surgeons and two orthodontists rated their aesthetical evaluation from 1 to 5. Experimental group consisting of 47 female and 38 male patients who had rotational orthognathic two-jaw surgery from 2010 to 2011 were chosen according to aesthetic scoring done by two maxillofacial surgeons and two orthodontists. A high aesthetic score (${\geq}16$) means the facial contour is symmetric, with no broad and narrow aesthetic mandible frontal profiles. Control A group consisted of ten female and ten male patients who had no orthognathic surgery experience and low aesthetic score (${\geq}10$). Control B group consisted of ten female and ten male patients who had no orthognathic surgery experience and had anaesthetic mandibular frontal profile and a high aesthetic score (${\geq}16$). The three-dimensional image of the patient was taken from dental cone-beam CT (DCT) scanning (experimental group and control A group: 6 months DCT after surgery, control B group: 1st visit DCT). Each DCT was reformatted to reorient the 3D image using 3D analyzing program (OnDemand3D, cybermed Inc, CA, USA). After selection of 12 landmarks and the construction of reoriented horizontal, vertical, and coronal reference lines, 15 measurements were taken in 3D analysis of frontal mandibular morphology. Afterwards, horizontal and vertical linear measurements and angular measurements, linear ratio were obtained. Results: Mean $Go^{\prime}_{Rt}-Me^{\prime}-Go^{\prime}_{Lt}$ angular measurement was $100.74{\pm}2.14$ in female patients and $105.37{\pm}3.62$ in male patients. These showed significant difference with control A group in both genders. Ratio of $Go^{\prime}_{Rt}-Go^{\prime}_{Lt}-Me^{\prime}$ length to some linear measurements (ratio of $Me^{\prime}-Cd^{\prime}_{Rt}Cd^{\prime}_{Lt}$ to $Me^{\prime}-Go^{\prime}_{Rt}Go^{\prime}_{Lt}$, ratio of $Me^{\prime}-Go^{\prime}$ to $Me^{\prime}-Go^{\prime}_{Rt}Go^{\prime}_{Lt}$, ratio of $Go^{\prime}_{Rt}-Go^{\prime}_{Lt}$ to $Me^{\prime}-Go^{\prime}_{Rt}Go^{\prime}_{Lt}$) showed significant difference with control A group in both genders. Conclusion: This study was intended to find some standard measurement of mandible frontal view in 3D analysis of aesthetic patient. So, these potential measurement value may be helpful for orthognathic treatment planning to have more aesthetic and perspective outcomes.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.407-418
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• 2017

Due to geographical features of being close to DPRK (Democratic People's Republic of Korea), the Imjin River basin has difficulties in hydrological observation, and is vulnerable to unexpected flood occurrence. As a countermeasure, Gunnam Flood Control Reservoir construction was planned in 2005. Despite such a structural measure, damages by DPRK's illegal release continues to occur. Futhermore the Imjin River's flow has been decreased due to the effect of continuous drought in the Korean Peninsula since 2012 and DPRK's unilateral storage of water. A new operation method is derived for the Gunnam Flood Control Reservoir in order to cope with drought damages on the Imjin River basin and to ensure efficient response time upon flooding. The operation method maintaining Gunnam Flood Control Reservoir's water level by raising from EL.23.0 m to EL.31.0 m during the flood season for securing reservoir capacity enables to secure additional $14,000,000m^3$ water compared to the existing operation methods. The operation method to store inflow by controlling release to $250m^3/s$ in the early stage of flood has increased 2.66% on average in terms of detention effect of reservoir compared to the existing operation methods. The method enables to secure 19 hours to prepare flood compared to the existing methods.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.57-68
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• 2007

The mega frame system is becoming popular for the design and construction of skyscrapers because this system exhibits structural efficiency by allowing high rigidity of the structure while minimizing the amount of structural materials to be used. Since the mega frame system is usually adopted for super high-rise buildings, the comfort of occupants may be main concerns in the practical application of this system. For the enhancement of the serviceability of mega frame structures, a semi-active tuned mass damper (STMD) is developed in this study. To this end, a Magnetorheological (MR) damper is employed replacing passive damper as a semi-active damper to improve the control effect of a conventional TMD. Since a conventional finite element model of mega frame structures has significant numbers of DOFs, numerical simulation for investigation of control performances of a STMD is impossible by using the full-order model. Therefore, a reduced-order system using minimal DOFs, which can accurately represent the dynamic behavior of a mega frame structure, is proposed in this study through the matrix condensation technique To improve the efficiency of the matrix condensation technique, multi-level matrix condensation technique is proposed using the structural characteristics of mega frame structures. The efficiency and accuracy of the reduced-order control proposed in this study and the control performance of a STMD were verified using example structures.

• Journal of Drive and Control
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• v.12 no.4
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• pp.60-70
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• 2015

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements for farm work. However, when the tractor carries material using the bucket attached to the FEL on a sloping ground, the materials can spill or roll back over the operator due to the tilted body, thereby requiring the bucket surface to remain level at a constant value regardless of varying slopes. In this study, an active system for controlling the angle of the FEL bucket on a tractor based on the real-time measurement of ground slopes was developed to enable the bucket to constantly remain level. A FEL simulator operated based on an electro hydraulic proportional valve (EHPV) was constructed in the laboratory to develop a proportional-integral-derivative (PID) controller forming a virtual electronic control unit (ECU) on the computer, which could automatically adjust the bucket angles depending on varying input angles while sending SAE-J1939 associated messages via CAN BUS to the EHPV. The different parameter values for the PID controller due to the gravity effect of the bucket were determined using a manual PID tuning method while assuming that the tractor travels on either an ascending slope or a descending slope. The developed PID control-based self-leveling system showed a mean of steady-state errors of within $1^{\circ}$ and a mean of delayed times of ~ 0.8s when the step input of $+20^{\circ}$ was given, implying that the developed system and control algorithm would be effective in maintaining the bucket angle at a certain value. Future studies include the improvement of the control algorithm to reduce such a time delay as well as the application of the developed algorithm to the FEL mounted on a tractor tested at a testing ground.

• Journal of Korea Water Resources Association
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• v.41 no.8
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• pp.773-784
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• 2008

The present study was carried out to examine flow properties in linear drainage channels such as road surface drainage facilities. The finite difference formulation for the varied flow analysis was solved for flow profiles in the channels. Starting the first step at the control section, the Newton-Raphson method was applied for producing numerical solutions of the equation. We considered two types of linear drainage channels, a channel with one outlet at downstream end and a channel with two outlets at both ends. Moreover, the flow analysis for various channel slopes was performed. However, we considered channels with the two outlets of slopes satisfying the condition that the both ends are the control section. The maximum of those slopes was decided from the relation between the channel slope and the location of control section. The flow of a channel with one outlet was calculated upward and downward from the control section existing in channel or upward from the control section at downstream end. The flow of a channel with two outlets at both ends were calculated for upstream and downstream channel segments divided by the water dividend, respectively and the flow analysis was completed when the water depth at the water dividend calculated from upstream end was equal to that calculated from downstream end. If the slope was larger than the critical slope, the channel with two outlets was likely to behave like the channel with one outlet. The maximum water depth was investigated and compared with that calculated additionally from the uniform flow analysis. The uniform flow analysis was likely to lead a excessive design of a drainage channel with mild slope.

• Journal of the Korea Concrete Institute
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• v.23 no.1
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• pp.109-120
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• 2011

This paper presents an experimental study results on the crack control of flexure-dominant reinforced concrete beams repaired with strain-hardening cement composite (SHCC). Five RC beams were fabricated and tested until failure. One unrepaired RC beam was a control specimen (CBN) and remaining four speciemens were repaired with SHCC materials. The test parameters included two types of SHCC matrix ductility and two types of repair method (patching and layering). Test results demonstrated that RC beams repaired with SHCC showed no concrete crushing or spalling until final failure, but numerous hair cracks were observed. The control specimen CBN failed due to crushing. It is important to note that SHCC matrix can improve crack-damage mitigation and flexural behavior of RC beams such as flexural strength, post peak ductility, and energy dissipation capacity. In the perspective of crack width, crack widths in RC beams repaired with SHCC had far smaller crack width than the control specimen CBN under the same deflection. Especially, the specimens repaired with SHCC of PVA0.75%+PE0.75% showed a high durability and ductility. The crack width indicates the residual capacity of the beam since SHCC matrix can delay residual capacity degradation of the RC beams.

• The Korean Journal of Elementary Counseling
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• v.4 no.1
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• pp.215-236
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• 2005

The Purpose of this study is that self-growth program searches effect self-concept and peer-relationship with elementary school student, and advance following assumption to achieve this purpose and achieved study. First, self-concept point of experiment group students who execute self-growth program will be improved is meaning than self-concept point of control group students. Second, peer-relationship point of experiment group students who execute self-growth program will be improved is meaning than peer-relationship point of control group students. Third, effect that self-growth program gets to self-concept may be meaning difference according to sex. Fourth, difference that impact that self-growth program gets in peer- relationship is meaning according to sex may join. Chose fifth-year student 2 class 68 people (experiment group n=34, control group n=34) in I primary school locating to Jeonrabuk-do Iksan-si to verify above construction for study target. Disposal about experiment group executed over 10th for 60-80 minute 2 times in a week because investigator uses reconstructing self-growth program with virtue research paper such as learning program for own growth of Lee-Hyeong-Deuk (1998). In order to verify the effect after experiment, 1 collected materials for estimation by providing the subject children with questionaires about self-concept and peer-relationship before and after the experiment, and then analyzed the average differences in number of marks between the experiment group and the control group before and after the experiment through and by using One-Way ANOVA, and SPSS 11.0 program. The following is the result what I obtained from the above study. First, there was significant difference is between average difference before and after of experiment group and control group which execute self-growth program in self-concept elevation ($F_{(1,66)} =28.734$, p <.001). From the sub-variable, there was significant difference in academic self ($F_{(1,66)}=6.423$, p<.05), Social Self ($F_{(1,66)}=48.331$, p<.001), Physical Self ($F_{(1,66)}=11.074$, p <.01), sentimental self ($F_{(1,66)}=9.402$, p <.01) Second, there was significant difference is average difference before and after of experiment group and control group which execute self-growth program in peer-relationship promotion ($F_{(1,66)}=24.109$, p <.001). From the sub-variable there W3S Significant difference in trust ($F_{(1,66)}=14.507$, p<.001), respect ($F_{(1,66)}=15.271$, p <.001). Third, there was expose that significant difference does not exist in average self-concept before and after by sex of experiment group which executes self-growth program, and was not shown significant difference in sub-vairable. Fourth, there was expose that significant difference of whole peer- relationship and in respect of sub-variable in average peer-relationship before-after by sex of experiment group which execute self-growth program, but significant difference did not appear in trust. Could get conclusion that self-growth program is effect in elementary school student self-concept elevation and peer-relationship promotion according to these study finding, and confirmed possibility that self-growth program may contribute to change emotional special quality of children positively in education spot.

• Advances in concrete construction
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• v.13 no.3
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• pp.215-221
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• 2022

Considering their similar mass densities, an attempt was made to optimize the mix design of micro-concrete that used barite sand as an aggregate by substituting marble powder (5%, 10%, 20%, 30%, 40%, 50%, 70%), clay brick powder (30%, 50%, 70%), and fly ash (30%, 50%, 70%) for the concrete (by mass) to form specimens for shaking table tests. The test results showed that for these three groups of materials, the substitutions had little effect on the density. The barite sand played a decisive role in the density, and the overall density of the specimens reached approximately 2.9 g/cm³. The compressive strength and elastic modulus decreased with an increase in the substitution rates for the three types of materials. Among them, the 28 day compressive strength values of the 40% and 50% marble powder groups were 11.73 MPa and 8.33 MPa, respectively, which were 58.7% and 70.7% lower than the control group, respectively. Their elastic modulus values were 1.33×10⁴ MPa and 1.42×10⁴ MPa, respectively, which were 39.1% and 35% lower than those of the control group, respectively. The 28 day compressive strength values of the 50% and 70% clay brick powder groups were 13.13 MPa and 5.8 MPa, respectively, which were 53.8% and 79.6% lower than the control group, respectively. Their elastic modulus values were 1.54×10⁴ MPa and 1.19×10⁴ MPa, respectively, which were 29.7% and 45.4% lower than those of the control group, respectively. The 28 day compressive strength values of the 50% and 70% fly ash groups were 13.5 MPa and 7.1 MPa, respectively, which were 52.5% and 75% lower than those of the control group, respectively. Their elastic modulus values were 1.36×10⁴ MPa and 0.95×10⁴ MPa, respectively, which were 37.9% and 56.6% lower than those of the control group, respectively. There was a linear relationship between the 28 day compressive strength and elastic modulus, with the correlation coefficient reaching a value higher than 0.88. The test results showed that the model materials met the high density, low compressive strength, and low elastic modulus requirements for shaking table tests, and the test data of the three groups of different alternative materials were compared and analyzed to provide references and assistance for relevant model testers.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.52-63
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• 2009

Recently in Korea, in the case of metropolis, the urban signalized intersections are controlled by traffic information center or ITS center. Cheon-an City also established traffic information center through the 1st.-$\sim$3rd. ITS public construction and has managed this center that includes bus information service, traffic information collection and providing service, parking information service, and traffic responsive control system. In the Cheon-an metropolitan traffic signal operation, traffic signal controllers were grouped by the each main traffic flow axes and performed with coordinated signal timing for the signalized arterials, and also cycle and split changed by realtime traffic demands. Cheon-an urban traffic responsive control system was evaluated by intersection delay and speed, then it was verified that the delay decreased and vehicle speed improved. However, the rural signal control system to connect adjacency town was evaluated to have lower status than urban area due to the unimproved TOD (Time of day) plan. Therefore actuated signal control was examined for substitutive control system in isolated signal intersection. The aim of this article is to compare actuated signal control with TOD mode in the rural intersection of Cheon-an and to fine superiority of these two control mode, with evaluation of vehicle delay by using HCM(2000) method and by micro-simulation CORSlM. The result of field test show that actuated signal control gave better performance in delay comparison than the existing TOD signal control. And simulation outcome verified that non-optimized TOD has higher delay than optimized TOD mode, non-optimal actuated mode, and optimal actuated signal control mode. Particularly, these three modes delays had not different values according to the paired sample t-test. This is because small traffic demands were loaded in each links. This suggested actuated signal control is expected to be more effective than TOD mode in some rural isolated intersections which frequently need to survey for traffic volume.