• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1210-1215
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• 2010

Unit cabin means room, which is installed in the high value-added vessel such as drill ship, offshore platform and FPSO, after pre-assembled. In order to develop the noise control design for a unit cabin, a variety of acoustic tests such as sound absorption, transmission and radiation measurements were carried out by using the deckhouse mock-up. From the tests, it was found out that the sound transmission loss between cabin and corridor was 13 dB below than FPSO standard and the combined noise level of the unit cabin was dominated by the radiated noise from wall panel in low frequency range. Based on the test results, design guidelines for the noise control of the unit cabin were fully established, such as the improvement of sound transmission loss between the cabin and corridor, and radiated cabin noise reduction.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.10
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• pp.5-17
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• 1995

기계가공(Machining)중에서 가장 기본적인 것이 선삭(Turning)작업이며, 이 가공은 선반(Lathe)에 의해서 행하여지고 있는 것은 다 아는 사실이다. 공작기계의 발달과 금속 절삭 원리(Principles of metal cutting)는 선반을 중심으로 약 일세기동안 꾸준히 발전해 오고 있으며, 수없이 쏟아져 나온 연구논문들의 대부분이 선반에 의한 가공과 그 공작기계에 의해서 이루어졌으며 앞으로도 계속 보통선반, CNC선반의 토대 위에서 이루어지리라고 보고 있다. 공작기계 중에서 CNC 선반의 발달 과정을 요약해보면 1960년대의 대량 생산시대에는 Programmable control 방식의 자동 터렛트(Turret) 선반이 개발되어 생산 공정이 비교적 간단한 양산 가공기로서 환영을 받게 되었다. 1970년대에 들어서면서 다품종소량생산이 중요시되었고, 그때 NC 선반시대가 시작되었다고 볼 수 있다. 현 싯점에서 볼 때 이것은 중품종중량생산 이라고 말할 수 있으며, Turret 선반의 NC화 즉, Multi-tool에 의한 선반의 복합가공이 가능해졌지만 Tooling에 문제가 발생하였다. 1980년에 들어서 각종 MC 들이 광범위하게 발달, 보급되는 경향에 따라서 NC 선반도 고능률화의 일환으로 고속화와 더불어 회전공구인 End mill. Drill. Tap 등의 복합가공이 가능한 복합선반이 차례로 개발되었고 선삭공구와 회전공구등의 자동공구교환(Automatic Tool. Changing. ATC)이 가능해지고 Y축 보정(Co-mpensation)기구를 부착한 대형 Turning center가 개발되어 보급되게 되었다.

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.193-206
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• 2014

Residual performance of old architectural wood which has been damaged was measured using Nondestructive Evaluation (NDE). The wood Pole Tester was used to assess ultrasonic velocity inside wood and drill resistance was determined using an IML-resistograph. For ultrasonic measurements squared timber and circular timber's measurements were separately conducted with 1,300 m/s as the standard ultrasonic velocity. The standard wood samples divided into two parts; a non-sound area (below the standard), and a sound area (above the standard). Furthermore, schematization of wood was compared with results naked eye observation. The drilling resistance test was performed for both length and thickness direction in wood. The internal of the drilling was set at 30 cm (length direction), 5 cm (width direction) and 30cm (thickness direction). A non-sound area was defined as that 1) amplitude is below 20% and 2) carbonization and deterioration are related.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.2
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• pp.193-198
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• 2004

This is the dissertation of the study of design characteristics about the practical flexible manufacturing system (PFMS). The basic ideas to analyze the manufacturing system which is the automatically operated is dependant on the various manufacturing procedures in factory. PFMS is the very useful equipment for students and trainee of production lines. This system is composed of hardware and software sub systems i.e. control and test unit and personal computer with software. The PFMS can be developed with design concepts and approved the capability of first article with functional tests. The PFMS module will be very useful for the manufacturing drill system in universities and practical fields. The flexible manufacturing systems have various subsystems appropriated for the final manufacturing products. Therefore the systems have the various kinds of hard wares as well as softwares. We study the software for the practical flexible manufacturing system designed in the Halla University and specially the design concept and using specification of the SCARA (Selective Compliance Assembly Robot Arm) robot which is used for the movement of the product is analyzed and introduced in this dissertation.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.13-19
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• 2010

Due to the rapid spread of mobile handheld devices, industrial demands for micro-scale holes with a diameter of even smaller than $10{\mu}m$ in sapphire/silicon wafers have been increasing. Holes in sapphire wafers are for heat dissipation from LEDs; and those in silicon wafers for interlayer communication in three-dimensional integrated circuit (IC). We have developed a sapphire wafer driller equipped with a 532nm laser in which a cooling chuck is employed to minimize local heat accumulation in wafer. Through the optimization of process parameters (pulse energy, repetition rate, number of pulses), quality holes with a diameter of $30{\mu}m$ and a depth of $100{\mu}m$ can be drilled at a rate of 30holes/sec. We also have developed a silicon wafer driller equipped with a 355nm laser. It is able to drill quality through-holes of $15{\mu}m$ in diameter and $150{\mu}m$ in depth at a rate of 100holes/sec.

• Tunnel and Underground Space
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• v.5 no.2
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• pp.114-122
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• 1995

The principle and applications of GPR(Ground Penetrating Radear) are familiar to engineering geologists and geophsicists as very attractive technique for continuous high resolution images of the subsurface. However, the main limitation of GPR is obviously related to presence of clayey or silty conductive soils, resulting in complete attenuation of radar signals. This difficulty gives hesitation for the exploration of the deeper targets for example detecting bedrock, particularly in Korean situation that most regions have conductive overburden. In order to prove usefulness of geological survey with GPR in that situation, the technique was tried to investigate depth of bedrock under thick conductive overburden and the other geolocgical informations for the constructionof foundation in the Dongbu apartment site, Kimhae. The reflection patterns on the processed GPR sections are well correlated with the geotechnical units-bedrock, alluvium, landfill unit and their internal layer-boundaries of boring data before GPR survey, except upper contact of bedrock. The isopach maps of the geotechnical units for the 3-D interpretations are made from GPR sections. The maps provided useful geological information that bedrock was distributed as plain and valley with 22~27m depth under alluvium unit (this depth is 5~8 m deeper than drill log) and sedimentary layers subsided and bended along growth fault with NNE strike/15$^{\circ}$SE dip in alluvium unit.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.4
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• pp.290-297
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• 1997

Underwater robotic vehicles(URVs) are used for various work assignments such as pipe-lining, inspection, data collection, drill support, hydrography mapping, construction, maintenance and repairing of undersea equipment, etc. As the use of such vehicles increases the development of vehicles having greater autonomy becomes highly desirable. The vehicle control system is one of the most critic vehicle subsystems to increase autonomy of the vehicle. The vehicle dynamics is nonlinear and time-varying. Hydrodynamic coefficients are often difficult to accurately estimate. It was also observed by experiments that the effect of electrically powered thruster dynamics on the vehicle become significant at low speed or stationkeeping. The conventional linear controller with fixed gains based on the simplified vehicle dynamics, such as PID, may not be able to handle these properties and result in poor performance. Therefore, it is desirable to have a control system with the capability of learning and adapting to the changes in the vehicle dynamics and operating parameters and providing desired performance. This paper presents an adaptive and learning control system which estimates a new set of parameters defined as combinations of unknown bounded constants of system parameter matrices, rather than system parameters. The control system is described with the proof of stability and the effect of unmodeled thruster dynamics on a single thruster vehicle system is also investigated.

• Economic and Environmental Geology
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• v.31 no.5
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• pp.375-388
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• 1998

The purpose of this study is to investigate the ore genesis and occurrence of the Wondong polymetallic mineral deposits. The Pb-Zn, Fe and W-Mo mineralizations are found in skarn zones which formed mainly in or along the fault shear zones with the $N25-40^{\circ}W$ and $N10-50^{\circ}E$ directions, whereas the Cu-Mo mineralization is appeared hydrothermal replacement zone. The skarn minerals consist mainly of garnet and epidote, which were the last alteration phases between pneumatolytic and hydrothermal stages. The mineral paragenesis toward the late stage are as follows: arsenopyrite, scheelite, magnetite, pyrite, pyrrhotite, sphalerite, galena, chalcopyrite and molybdenite. Average ore grades are 0.33 g/t Au, 46.29 g/t Ag, 0.06% Cu, 4.4% Pb, 2.61% Zn and 29.39% Fe in tunnels, and 0.31 % Cu, 0.52% Pb, 6.29% Zn, 29.29% Fe, 0.03% Mo and 0.12% $WO_3$ in drill cores. Fluid inclusion data shows that Type I (liquid-rich), Type II (vapor-rich) and Type III (halite-bearing) inclusions are coexisted and their homogenization temperatures are quite similar. This indicates that boiling conditions have been reached during the mineralization. It is also likely that the ore solutions were evolved through the mixing between magmatic and meteoric waters. Rhyolite and quartz porphyry far the mineralization probably are not responsible of the Wondong polymetallic mineral deposits.

• Explosives and Blasting
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• v.31 no.1
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• pp.23-32
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• 2013

Construction vibration such as explosive blast, hydraulic breaker, vibratory roller, pile driving noise and so on, injuries in areas around the construction sites. In particular, underwater sound caused by ground vibration is propagation such as structure borne noise. Vibration and underwater sound due to construction activities may cause injury to river, sea or land fish farms near construction sites. The purpose of present study is to measure the sound pressure level and frequency analysis of the underwater noise generated by ground vibration(Blasting, hydraulic crawler drill, hydraulic breaker, vibratory roller). Underwater noise were monitoring by a hydrophone (TC 4013) and recorded, analysis were made using a by software (Prosig).

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.195-198
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• 2009

Rammed Aggregate Pier method is intermediate foundation of deep and shallow foundation, it has been built on world wide. But the investigation and research in domestic is not accomplished. In this paper, examined details of different spacing of piles, bearing capacities, respectively, conclude with recommendations on how RAP can be used in future needs. This documentation further provides comparisons of the laboratory test results which were obtained from differenciate the spacing of piles, namely installed rammed aggregate pier. Strain control test was conducted to determine the bearing capacities of the piers; 20mm, 30mm and 40mm diameter drilling equipment to drill holes were installed in sand at initial relative densities of 40%. By comparing different spacing of piles, in this experiment, piles are spaced structually span, form a ring shape, narrowing the distance of each other, to the center. the result shows that as diameter of pier is bigger in diameter, bearing capacity also dramatically increased due to raised stiffness. Also, the space between each piers narrowed, settlement rate of soil was decreased significantly. From the test results, as the space between each piles were getting closer, allows greater chances to have resistance to deformation, shows improved stability of structures.