• 한국양식학회지
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• 제11권4호
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• pp.465-474
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• 1998

참전복(Haliotis discus hannai) 양성과정중 치패단계에서 발생된 패각 괴사증의 조사결과는 다음과 같다. 괴사된 전복패각에서 간균 형태(rod type)와 이질세포를 갖는 남조류가 관찰되었다. 그러나 주사전자현미경(SEM)의 자료에 근거하면 패각과 사증의 원인생물은 천공성 남조류, Mastigocoleus sp.로 나타났다. 천공성 남조류에 감염된 전복의 패각은 녹색에서 회백색으로 탈색되었고, 4~6번째 호흡공은 부서지기 쉬운 상태가 되었다. 양성 60일 후, 패각 괴사증은 갈색의 작은 집락이 산재되어있는 호흡공에서 주로 발생하였으며, 양성 후 3년까지 지속되었다. 이러한 패각 괴사증은 바다 채롱식 양식장에서 보다는 육상 수조식 양식장에서 주로 발생하였으며, 참전복의 성장에 커다란 영향을 미친 결과 3년산 참전복의 각장이 16mm였다.

• Geomechanics and Engineering
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• 제29권3호
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• pp.321-329
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• 2022

Tunnel site where high water pressure is applied, such as subsea tunnel, generally selects the shield TBM (Tunnel Boring Machine) to maintain the tunnel excavation face. The shield TBM has cutters installed, and the cutters wear out during the process of excavation, so it should be checked and replaced regularly. This is called CHI (Cutterhead Intervention). The conventional CHI under high water pressure is very disadvantageous in terms of safety and economics because humans perform work in response to high water pressure and huge water inflow in the chamber. To overcome this disadvantage, this study proposes a new method to dramatically reduce water pressure and water ingress by injecting an appropriate grout solution into the front of the tunnel face through the shield TBM chamber, called New Face Grouting Method (NFGM). The tunnel model tests were performed to determine the characteristics, injection volume, and curing time of grout solution to be applied to the NFGM. Model test apparatus was composed of a pressure soil tank, a model shield TBM, a grout tank, and an air compressor to measure the amount of water inflow into the chamber. The model tests were conducted by changing the injection amount of the grout solution, the curing time after the grout injection, and the water/cement ratio of grout solution. From an economic point of view, the results showed that the injection volume of 1.0 L, curing time of 6 hours, and water/cement ratio of the grout solution between 1.5 and 2.0 are the most economical. It can be concluded that this study has presented a method to economically perform the CHI under the high water pressure.

• 터널과지하공간
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• 제32권6호
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• pp.478-490
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• 2022

TBM의 주요 절삭도구인 디스크커터는 과다하게 마모되거나 손상된 경우 적절한 시기에 교체되어야 한다. 일반적으로 커터의 교체여부를 판단하기 위해서 작업자가 커터헤드 챔버의 내부로 접근하여 디스크 커터의 상태와 마모량을 계측하고 있다. 하지만 커터헤드(cutterhead) 챔버(chamber) 내부는 작업자에게 열악한 조건일 경우가 많아 작업자의 안전과 관련한 이슈가 있으며, 인력에 의해서 계측이 이루어짐에 따라 계측치의 오차도 발생하는 것으로 보고되고 있다. 이러한 한계점을 극복하고자 현재 해외에서는 디스크커터의 마모정도를 계측센서를 통해 굴착 중에 실시간으로 측정하기 위한 기술의 개발이 활발하게 이루어지고 있으며, 본 연구에서는 현재까지 해외의 문헌을 통해 보고되고 있는 TBM 디스크커터의 마모량 계측에 관한 연구현황에 대하여 소개하고자 하였다. 여러 형식의 센서가 디스크커터의 마모계측을 위해 활용되고 있으며, 향후 국내에서도 유사한 기술의 개발이 이루어지는 경우에 유용한 참고자료가 될 수 있을 것으로 판단된다.

• 터널과지하공간
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• 제32권6호
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• pp.345-352
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• 2022

도심지 터널 건설에서 발파공법은 민원이 제기되는 문제점이 있어 적용에 제약받고 있다. 이에 대한 대안으로 TBM 및 기계굴착 공법 적용이 필수적으로 검토되고 있다. 이 중 쉴드 TBM(Tunnel Boring Machine)은 굴진과 세그먼트 체결이 번갈아 반복되며 굴진하는 공정을 가지고 있는데, 세그먼트 체결 동안 굴진을 멈추게 된다. 이러한 가동 정지시간을 최소화하고자 세그먼트 체결 중에도 가동할 수 있는 연속굴착형 TBM 기술이 개발되고 있다. 나선형 세그먼트의 굴진 반력을 확보하기 위해 추진잭을 개조하고 신뢰성을 확보하는 연구가 진행 중이다. 또한 체결 중 세그먼트를 제외한 나머지 부분의 추진잭을 가동하는 유압제어 및 유압시스템 설계기술이 개발될 예정이다. 본 보고는 연속굴착형 TBM 과제 중 부품개조 및 유압제어 기술에 대한 일부 내용을 소개한다.

• 한국공작기계학회논문집
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• 제11권1호
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• pp.10-16
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• 2002

This study is to evaluate the tool performance in honing using diamond reamer and present grounds whether the localized products are sufficiently competitive comparing with the existing imported ones. The heads of the tool performance evaluation are roundness, roughness, tool life of the workpiece and so on. When evaluating the tool performance, cutting process is divided by three areas which are rough semi-finish and finish cut. cloning improves the accuracy such as boring and reaming after manufacturing the inside diameter, and finishing directly by honing is a recent trend. This honing is used greatly In hard cutting materials like cemented carbides and it is the CBN and diamond that is used in hard cutting materials. Both of them are expensive and most oi them are imported.

• Journal of Advanced Marine Engineering and Technology
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• 제18권2호
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• pp.64-74
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• 1994

The gundrill is capable of machining for having large length to diameter ratio in single pass. The techniques of gundrill and gun boring began developing in the late 18th century with the need for more accurate bores in rifle, cannon, machinery part and marine part etc. The main feature of the gun drilling provides a stabilizing cutting force resultant necessary for self guidance of the drill head. A study of the accuracy and surface finish of holes produced would reveal quite useful information regarding the process. The thesis deals with the experimental results obtained during gun drilling on marine part materials for different machining conditions.

• Geomechanics and Engineering
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• 제38권2호
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• pp.179-189
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• 2024

This paper presents a geomechanical framework for designing and optimizing layout patterns of cutterheads for rock Tunnel Boring Machines (TBMs), aiming to enhance their engineering performance. By examining the forces and moments exerted by rock, the study addresses geometric constraints associated with cutter boxes in key regions of the cutterhead, including the center, face, and gage areas, as well as the three-dimensional effects of cutterhead curvature on the geometric constraints of the back of the cutter boxes in the gage area. Novel formulas are proposed for determining the center points of cutter boxes and calculating both the minimum angular spacing and distance spacing between consecutive cutter boxes along a spiral path. The paper outlines an optimized layout design process for four cutterhead configurations: random, random paired, radial, and double spiral designs. Examples are provided to illustrate the results of applying these designs. The findings underscore the efficacy of the proposed methods in achieving a uniform and symmetrical distribution of cutters and buckets on the cutterhead surface. This approach effectively eliminates boundary overlap and minimizes unbalanced forces and moments. From a geomechanical standpoint, this framework offers a robust strategy for enhancing the performance and reliability of TBM cutterheads in rock tunneling operations.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2256-2261
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• 2017

Carbon nanotube (CNT) and alumina ($Al_2O_3$) are synthesized into hybrid composites, and an advanced electrical discharge machining (EDM) system is developed for the machining of hard and conductive materials. CNT nanoparticles are mixed with $Al_2O_3$ powder and the $Al_2O_3$/CNT slurry is sintered by spark plasma. The hardness and the electrical conductivity of the $Al_2O_3$/CNT hybrid composite were investigated. The electrical discharge is controlled by a capacitive ballast circuit. The capacitive ballast circuit is applied to the tungsten carbide and the $Al_2O_3$/CNT hybrid composite. The voltage-current waveforms and scanning electron microscope (SEM) images were measured to analyze the characteristics of the boring process. The developed EDM process can manufacture the ceramic based hybrid composites, thereby expecting the variety of applications.

• 한국기계가공학회지
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• 제11권4호
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• pp.147-153
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• 2012

The demands of the large scale machine tools, for instance, such as planomiller, turning machine, boring machine, NC machine, have been gradually increased in recent years. As the performances of machine tools and/or cutting tools are advanced, it is possible to perform high-speed and high-precision cutting works. The effective treatment of wet chip, which is discharged from cutting works, becomes very important problems. Therefore, this study is forced on the design of large scale machine tools using CATIA V5R18 and analysis of cutter, which is considered as essential equipment in large scale machine tools, using MSC.Nastran & MSC.Patran. Especially, the relations between tolerated load of cutter, driving horse power and rpm of driving shaft in chip processing system are investigated through analysis. As the results, the reliability of design could be improved by evaluating simulated numerical values, it showed that tolerated loads of supported part and edged part of cutter are 87,000N and 14,450N, respectively.

• 화약ㆍ발파
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• 제26권1호
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• pp.49-55
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• 2008

터널 및 지하공동 폐기물 처분시설의 건설에서 여굴을 적게하고 굴착후 잔류암반의 안정성을 높이기 위하여 TBM 및 할암기 등의 기계적 굴착공법의 적용이 제안되고 있다. 그러나 기계적 굴착공법은 경비나 시공성, 현장 적용성에 있어서 많은 제약이 따르고 있다. 이러한 단점을 보안하기 위하여 고도의 정밀제어발파공법이 제안되고 있다. 특히 노치 장약공을 이용하여 예정된 굴착면을 따라 정밀하게 파단면을 형성시키는 방법이 제안되고 있지만 아직까지 균열제어에 관련된 연구가 미흡한 실정이다. 본 연구에서는 동적파괴과정해석코드를 이용하여 암반내 노치를 가진 발파공을 모델링하여 암반의 균열발생 메커니즘과 파괴과정을 수치해석적으로 검토하였다.