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System Design for Developing the Remote Controlled Sprayer of Pear Trees (배나무 무인 방제기의 개발을 위한 살포 시스템 설계)

  • Lee, Bong Ki;Min, Byeong Ro;Lee, Min Young;Hwa, Yoon Il;Choi, Dong Sung;Hong, Jun Taek;Lee, Dae Weon
    • Journal of Bio-Environment Control
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    • v.22 no.4
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    • pp.303-308
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    • 2013
  • A remote controlled sprayer has designed, manufactured and experimented to spray well on pear trees with pesticides. This study was executed to automate pest management of pear trees. Types of spray nozzle, which was used on the system, were analyzed experimentally to find an optimal spray equipment configuration with several nozzles. Attributions of ultrasonic sensors were analyzed to adjust spraying distance of an unmanned sprayer system. This paper investigated shapes of pear trees and cultivating environment of pear orchard. In order to select optimal spray environment, liquid distribution was measured while angle of nozzle was changed. Additionally, liquid distribution by distance and sprayed liquid capacity by side distance were measured. According to information of shapes of pear trees and cultivating environment of pear orchard, sprayer frames of an unmanned sprayer system were manufactured and sprayer frames were suitable for interval of pear trees. The sprayer system could adjust width of sprayer frames to 2.5 m and height of sprayer frames to 1.7 m. Optimal angle of nozzle, and optimal distance between objects and nozzle were 15 and 0.8 m. When side distance was placed from 1.2 m to 1.8 m, sprayed capacity reached to the highest amount.

Development and Evaluation of Hollow-head Precast Reinforced Concrete Pile (말뚝머리 중공 프리캐스트 철근콘크리트 말뚝의 성능 평가)

  • Bang, Jin-Wook;Hyun, Jung-Hwan;Ahn, Kyung-Chul;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.2
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    • pp.130-137
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    • 2017
  • Due to the economic growth and development of construction technology, a role of foundation to resist heavy loads has been increased. In this present study to improve the structural performance of reinforced concrete pile, the precast HPC pile reinforced with rebar and filling concrete was developed and the strength of pile was predicted based on the limit state design method. The safety of HPC pile strength was evaluated by comparing with the design values. The geometry of HPC pile is a decagon cross section with a maximum width of 500 mm and a minimum width of 475 mm, and the hollow head of pile thickness is 70 mm. The inner area of the hollow head part was made as the square ribbed shape presented in the limit state design code in order to achieve horizontal shear strength between pile concrete and filling concrete. From the shear test results, it was found that the stable shear strength were secured without abrupt failure until maximum load stage despite the shear cracks was found. Shear strength is 135% and 119% higher than that of design value calculated from limit state design code. The driving test results of HPC pile according to the presence of additional reinforcement showed the outstanding crack resistance against impact loads condition. From the bending test results the flexural load between PHC pile and HPC pile was 1.51 times and 1.48 times higher than that of the design flexural load of conventional PHC pile.

Study On Generating Compact Network RTK Corrections Considering Ambiguity Level Adjustment Among Reference Station Networks for Constructing Infrastructure of Land Vehicle (육상교통 인프라 구축을 위한 다중 네트워크 간 미지정수 수준 조정이 고려된 Compact Network PTK 보정정보 생성기법 연구)

  • Song, June-Sol;Park, Byung-Woon;Kee, Chang-Don
    • Journal of Advanced Navigation Technology
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    • v.17 no.4
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    • pp.404-412
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    • 2013
  • Network RTK is widely used especially for static applications so far, however, the demand for high accuracy positioning for kinetic users such as land vehicles is growing for safety and convenience reasons. Kinematic users move along the roads and the network where they receive corrections can be changed. Compact Network RTK corrections should keep consistency while network change. In this paper, we introduced a method of generating Compact Network RTK corrections considering network ambiguity level adjustment by formulation of corrections. We verified the proposed method for reference station networks across whole country. We also generated Compact Network RTK corrections using simulation and real GPS data from reference stations in South Korea and evaluated performance of users. As a result, the discontinuity between corrections from two networks reduced to 0.25 cycle from several cycles. And user could achieve less than 8 cm (2DRMS) horizontal position accuracy continuously regardless of network change.

Intentional Replantation of a Root-Fractured Tooth with Pulp Canal Obliteration (근관협착된 치근파절 치아에서 의도적 재식술 치험례)

  • Kim, Mihee;Lee, Sangho;Lee, Nanyoung
    • Journal of the korean academy of Pediatric Dentistry
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    • v.43 no.2
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    • pp.200-206
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    • 2016
  • Root fracture is defined as a fracture involving the dentin, cementum, and pulp. Most fractures occur in the maxillary anterior teeth between the ages of 11 and 20 years old. The treatment for root fracture in permanent teeth involves the reduction and fixation of the displaced coronal segment. When signs of pulp necrosis or inflammatory root resorption are present, root canal therapy should be performed. Since most apical fragments maintain pulp vitality, root canal therapy is typically limited to coronal fragments. However, it's too difficult to achieve a proper apical stop on coronal fragment. Intentional replantation involves performing root apex treatment outside the mouth after intentional extraction of the tooth in a controlled environment and then replanting it. The objective is 'perfect' root canal therapy. Intentional replantation may be used in cases of failed typical root canal therapy, problematic endodontic retreatment due to the existing restoration or a calcified root canal, and when apical surgery is contraindicated because of a lack of reasonable approaches. In this case, intentional replantation was carried out to treat a horizontal root fracture in a maxillary central incisor with a calcified root canal due to previous trauma. We achieved a clinically and functionally satisfactory result.

Shear Performance of Large-Diameter Composite PHC Pile Strengthened by In-Filled Concrete and Shear Reinforcement (속채움 콘크리트와 전단철근을 사용한 대구경 합성 PHC말뚝의 전단보강 성능)

  • Hyun, Jung-Hwan;Bang, Jin-Wook;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.6
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    • pp.67-73
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    • 2017
  • Recently, the demand for large diameter piles has been rapidly increased in order to secure the allowable bearing capacity of pile foundation due to the increase of large structures such as high rise buildings. In this study, to improve the shear capacity of a conventional PHC pile, a large diameter composite PHC pile strengthened by in-filled concrete and shear reinforcement was manufactured. All the piles were tested according to the shear strength test method of Korean Standard. As a result of the shear test, the F-type piles which are produced without shear reinforcement occurred abrupt horizontal cracks after flexural and inclined shear cracks occurred. On the contrary, the FT-type piles which are produced with shear reinforcement exhibited stable flexural and inclined shear cracks uniformly over the entire pile without abrupt horizontal cracks. Furthermore, the maximum load of the large diameter composite PHC pile improved to 2.9 times in the F series, and more than 3.3 times in the FT series compared to the conventional PHC pile. This result indicated that FT-type piles had excellent composite behavior due to the shear reinforcement and effectively prevented the unstable growth of inclined shear cracks.

A Study for In-situ Application of High Strength Antiwashout Underwater Concrete (고장도용 수중불분리성 콘크리트의 현장적용을 위한 연구)

  • 문한영;송용규;이승훈;정재홍
    • Journal of the Korea Concrete Institute
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    • v.13 no.4
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    • pp.336-345
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    • 2001
  • The construction of underwater structures has been increased, but underwater concrete hassome problems of quality deterioration and contamination around in-situ of civil and architecture; therefore, new materials and methods for them are demanded. In this paper in-situ application of underwater antiwashout concrete which is manufactured for trio purpose of not only decreasing suspended solids and the heat of hydration but also increasing long term strength was studied. In the case of mock-up test(Ⅰ), when underwater antiwashout concrete, whose slump flow was 58 cm, was placed in the mock-up test at a speed of 24 ㎥/hr, it took about a minute to flow to the side wall, and the surface was maintained at horizontal level. In this case, compressive strength of the core specimens in each section was higher than the standard design compressive strength of 240 kgf/㎠. In the case of mock-up test(II), pH value and suspended solids of high strength underwater antiwashout concrete were 10.0∼11.0 and 51 mg/ℓ at 30 minutes later, initial and final setting time were about 30, 37 hr, and the slump flow of that was 53±2 cm. In the placement at a speed of 27 ㎥/hr, there was no large difference in flowing velocity, with or without reinforcement and flowing slope was maintained at horizontal level. In this case, compressive strength and elastic modulus of the core specimens somewhat decreased as flowing distance was far : however, those of central area showed the highest value.

Evaluation of Vertical Vibration Performance of Tridimensional Hybrid Isolation System for Traffic Loads (교통하중에 대한 3차원 하이브리드 면진시스템의 수직 진동성능 평가)

  • Yonghun Lee;Sang-Hyun Lee;Moo-Won Hur
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.28 no.1
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    • pp.70-81
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    • 2024
  • In this study, Tridimensional Hybrid Isolation System(THIS) was proposed as a vibration isolator for traffic loads, combining vertical and horizontal isolation systems. Its efficacy in improving serviceability for vertical vibration was analytically evaluated. Firstly, for the analysis, the major vibration modes of the existing apartment were identified through eigenvalue analysis for the system and pulse response analysis for the bedroom slab using commercial structural analysis software. Subsequently, a 16-story model with horizontal, vertical and rotational degrees of freedom for each slab was numerically organized to represent the achieved modes. The dynamic analysis for the measured acceleration from an adjacent ground to high-speed railway was performed by state-space equations with the stiffness and damping ratio of THIS as variables. The result indicated that as the vertical period ratio increased, the threshold period ratio where the slab response started to be suppressed varied. Specifically, when the period ratio is greater than or equal to 5, the acceleration levels of all slabs decreased to approximately 70% or less compared to the non-isolated condition. On the other hand, it was ascertained that the influence of damping ratios on the response control of THIS is inconsequential in the analysis. Finally, the improvement in vertical vibration performance of THIS was evaluated according to design guidelines for floor vibration of AIJ, SCI and AISC. It was confirmed that, after the application of THIS, the residential performance criteria were met, whereas the non-isolated structure failed to satisfy them.

TREATMENT OF HORIZONTAL AND VERTICAL ROOT FRACTURE IN IMMATURE PERMANENT TEETH - A CASE REPORT (미성숙 치근의 수직 파절과 수평 파절의 치험례)

  • Song, Seung-Ho;Park, Ho-Won
    • Journal of the korean academy of Pediatric Dentistry
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    • v.31 no.1
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    • pp.92-97
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    • 2004
  • Traumatic injuries in the young peranent dentition are common, but root fractures, defined as fractures in volving dentin, cementum and pulp, are relatively uncommon. Case 1 is a 9-year-old boy who had a horizontal root fracture of his maxillary right central incisor in the apical third. Root canal therapy was performed in coronal segment and calcium hydroxide therapy was initiated. Six months after treatment, a periapical radiograph showed calcific tissue formation and normal root development. 1 year and 3 months later, the canal was permanently obturated with gutta-percha. Case 2 is a 7-year-old girl who had a vertical root fracture of her maxillary right central incisor. Fractured tooth was intentionally extracted atraumatically, and then the separated fragments are bonded with resin cement. the restored tooth was replanted into the original socket. Recalls up to 8 months showed normal mobility and no periapical pathosis. In these cases, we performed conservative treatment. Clinical and radiographic examination showed no pathosis or abnormality of the teeth and periodontal tissue.

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Effects of Double-diffusive Convection on the Mass Transport of Copper Ions in a Horizontal Porous Layer (수평 다공성유체층에서 이온의 물질전달에 대한 이중확산대류 효과)

  • Yoon Do-Young;Kim Min Chan;Choi Chang Kyun
    • Journal of the Korean Electrochemical Society
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    • v.2 no.2
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    • pp.98-105
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    • 1999
  • In the present study, buoyant force and its stabilizing effects in an electrostatic field were examined systematically in order to reduce the effect of natural convection with thermal stratification in a horizontal fluid-saturated porous layer. The correlation of ionic mass transport induced by double-diffusive convection in a horizontal porous layer has been derived theoretically. And the theoretical model was examined by electrochemical experiments. The theoretical correlation for mass transport which is satisfying Forchheimer's flow equation and based on the micro-turbulence model is derived as a function of soltual Darcy-Rayleigh number, thermal Darcy-Rayleigh number and Lewis number. In the experiment, the mass transport of copper ions in CuSO4H2SO4 solution is measured by electrochemical technique. By assembling theoretical correlation and experimental results, the mass transport correlation induced by double-diffusive convection is proposed as Sh=0.03054(RsDLeRaD)1/213.8788(RsDLeRaD)1/10 The present correlation looks flirty reasonable with comparing experimental results, and very promising for the applications of its prototype into various systems involving heat transfer as well as mass transfer, in order to control the effects of natural convection effectively.

Practical Design of the Sandmat Considering Consolidation Settlement Properties (연약지반의 침하특성을 고려한 샌드매트의 실용적 설계를 위한 고찰)

  • Lee, Bongjik;Kwon, Youngcheul;Lee, Jongkyu
    • Journal of the Korean GEO-environmental Society
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    • v.8 no.5
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    • pp.31-38
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    • 2007
  • The practical design method on sandmat uses a drain length, rate of consolidation settlement and permeability of sand as a major design factors. And, on the basis of this design process, it has been installed beneath the embankment with same thickness. However, the possibility the underestimation on the thickness of sandmat and the delayed drain have been pointed out by several authors caused by a differential settlement at the center and the end of embankment. In this study, therefore, the effect of the differential settlement on the thickness of sandmat and delayed drain through the numerical analysis of embankment was analyzed. As a result, a substantial sandmat thickness becomes small and the possibility of the delayed drain can be certified because of the development of differential settlement at the center and ends of embankment. As a countermeasure to overcome this problem, the applicability of the mound type sandmat was also investigated by the numerical method. It can be concluded that it maintains the designated substantial sandmat thickness throughout consolidation process, and is useful method to maintain the drain capacity. Especially, the mound type sandmat is effective method for a construction site where can cause a differential settlement such as embankment. Furthermore, it has to be designed on the basis of the accurate prediction of consolidation settlement as well as rate of consolidation settlement, drain length and permeability of sand.

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