• 한국지반공학회논문집
• /
• 제15권6호
• /
• pp.111-120
• /
• 1999

투수성 중간복토재로 인한 침출수 흐름 거동과 누적수위 저감을 위해 양수정을 이용한 수직배수공법의 적용 가능성을 흐름 수치해석 프로그램인 MODFLOW를 이용하여 분석하였다. 현장 양수시험과 순간충격시험으로부터 획득한 투수계수와 저류계수를 이용하여(장연수 외, 1999) 현장의 수리상황을 수치적으로 검증한 후, 매립지에서 누적수위를 저감하기 위한 양수정의 최적양수율, 영향반경, 수평드레인의 효용성을 분석하였다. 본 수치해석 결과 대상지역의 지반조사결과(장연수 외, 1999)에서도 나타났던 저투수성의 중간 복토재로인한 매립지내의 수직흐름을 방해하는 차수효과가 다시 확인되었다. 단정 양수시 120 ton/day까지 가능하였던 양수율은 수평드레인 추가후 300 ton/day까지 증가하였으나 드레인 길이가 시간-수위강하 곡선에 큰 영향을 주지는 않았다.

• 대한기계학회논문집A
• /
• 제26권8호
• /
• pp.1577-1584
• /
• 2002

This paper develops a finite element model for studying the occupant behavior and injury cofficients of a large-sized cab-over type truck. Since it does not have a room to absorb collision energy and deformation in front of the passenger compartment the deformation is directly transmitted to the passenger compartment. Moreover, since its steering column is attached on the frame, severe deformation of the frame directly affects on the steering wheel's movement. Therefore, if the occupant behavior and injury coefficients analysis is performed using a finite element model developed based on a sled test, it is very difficult to expect acquiring satisfactory results. Thus, the finite element model developing in this paper is based on the frontal crash test in order to overcome the inherent problems of the sled test based model commonly used in the passenger car. The occupant behavior and injury coefficients analysis is performed using PAM-CRASH installed in super-computer SP2. In order to validate the reliability of the developed finite element model, a frontal crash test is carried out according to a test method used fur developing truck occupant's secondary safety system in european community and japan. That is, test vehicle's collision direction is vertical to the rigid barrier and collision velocity is 45kph. Thus, measured vehicle pulses at the lower parts of the left and right B-pilla., dummy chest and head deceleration profiles, HIC(head injury criterial) and CA(chest acceleration) values, and dummy behavior from the frontal crash test are compared to the analysis results to validate reliability of the developed model.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 추계학술발표대회
• /
• pp.17.2-17.2
• /
• 2011

Double-walled carbon nanotubes (DWCNTs) were grown with vertical alignment on a Si wafer by using catalytic thermal chemical vapor deposition. This study investigated the effect of pre-annealing time of catalyst on the types of CNTs grown on the substrate. The catalyst layer is usually evolved into discretely distributed nanoparticles during the annealing and initial growth of CNTs. The 0.5-nm-thick Fe served as a catalyst, underneath which Al was coated as a catalyst support as well as a diffusion barrier on the Si substrate. Both the catalyst and support layers were coated by using thermal evaporation. CNTs were synthesized for 10 min by flowing 60 sccm of Ar and 60 sccm of H2 as a carrier gas and 20 sccm of C2H2 as a feedstock at 95 torr and $750^{\circ}C$. In this study, the catalyst and support layers were subject to annealing for 0~420 sec. As-grown CNTs were characterized by using field emission scanning electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. The annealing for 90~300 sec caused the growth of DWCNTs as high as ~670 ${\mu}m$ for 10 min while below 90 sec and over 420 sec 300~830 ${\mu}m$-thick triple and multiwalled CNTs occurred, respectively. Several radial breathing mode (RBM) peaks in the Raman spectra were observed at the Raman shifts of 112~191 cm-1, implying the presence of DWCNTs, TWCNTs, MWCNTs with the tube diameters 3.4, 4.0, 6.5 nm, respectively. The maximum ratio of DWCNTs was observed to be ~85% at the annealing time of 180 sec. The Raman spectra of the as-grown DWCNTs showed low G/D peak intensity ratios, indicating their low defect concentrations. As increasing the annealing time, the catalyst layer seemed to be granulated, and then grown to particles with larger sizes but fewer numbers by Ostwald ripening.

• 한국도로학회논문집
• /
• 제16권5호
• /
• pp.91-98
• /
• 2014

PURPOSES : This study is to develop a automate road mapping system using ARASEO(Automated Road Analysis and Safety Evaluation TOol) for road management. METHODS : The road survey van named ARASEO(Automated Road Analysis and Safety Evaluation TOol) was used to generate highway drawings for Korea National Road number 37 automatically. In order to generate the highway drawings for purpose of road management, it is required to acquired the information for highway alignment, road width and road facilities such as safety barrier and road sign. Therefore the survey van acquired and analyzed the road width, median and guardrail data using rear side laser sensor of ARASEO and recognized the traffic control sign and chevron sign using foreside camera images. Also the highway alignment which is the basic information for highway drawing can be analyzed by acquisition the every 1m positional and attitude data using GPU and IMU sensor and developed algorithm. Finally, in this research the CAD based drawing software was developed to draw highway drawing using the analysis result from ARASEO. RESULTS : This study showed the comparison result of the surveyed road width and drawing data. To make the drawing of the road, we made the Autocad ARX program witch run in CAD menu interface. CONCLUSIONS : Using this program we can create the road center line, every 500m horizontal and vertical ground plan drawing automatically.

• Ocean and Polar Research
• /
• 제26권2호
• /
• pp.299-309
• /
• 2004

Conductivity-temperature-depth (CTD) data obtained along a meridional section in the eastern tropical Pacific in July 2003 have been analyzed to identify various water masses, and to examine the hydrographic structure and zonal geostrophic currents in the upper 1000 m. Water mass analysis shows the existence of subtropical and intermediate waters, characterized by layers of subsurface salinity maximum and minimum, originating from both hemispheres of the Pacific. Vertical section of temperature in the upper 200 m shows the typical trough-ridge structure associated with the zonal current system for most of the tropical Pacific. Water with the lowest salinity of less than 33.6 was found in the upper 30 m between $8.5^{\circ}N$ and $10.5^{\circ}N$ in a boundary zone between the North Equatorial Current and North Equatorial Countercurrent. Temporal changes in water properties observed at $10.5^{\circ}N$ over a period of 9 days suggest both the local rainfall and horizontal advection is responsible for the presence of the low-salinity water. Development of a barrier layer was also observed at $10.5^{\circ}N$. In the North Equatorial Current region a local upwelling was observed at $15^{\circ}N$, which brings high salinity and cooler subtropical water to the sea surface. A band of countercurrent occurs in the upwelling region between $13^{\circ}N$ and $15^{\circ}N$.

• 대한조선학회논문집
• /
• 제50권6호
• /
• pp.407-413
• /
• 2013

In the conventional towing tank, the ordinary towing carriage has a speed barrier which caused not only by the limitation of the length of towing tank but also the limitation of acceleration. Therefore the length of the towing tank should be decided carefully from the planning stage of the towing tank construction. Consequently the acceleration of the towing carriage should be taken less than 0.06g practically to avoid the slip of the wheel on rail. Due to the increasing demand of the high speed experiments on the development of special novel ship, the requirement of the high speed towing carriage is continuously increased recently. When the minimum measuring time of the towing experiment is prescribed as five seconds, the carriage should be accelerated with higher than 0.12 g to get the speed of 18 m/sec even in the towing tank having a length of 400m in length approximately. This means that the requirement of acceleration is bigger than twice of the ordinary practices of carriage acceleration. In such a condition the exerted total power of motor could not converted to traction force for the acceleration of the carriage without slip. To over come these difficulties a pair of horizontal traction wheels are reinforced to each of the ordinary vertical carrier wheel and appropriate suspension system has been devised for the towing tank of super high speed operation. It is believed that the design of novel suspension system adaptable for the high speed acceleration of towing carriage will play a important role as a reference for the remodeling of the towing tank for high speed experiment.

• Journal of Positioning, Navigation, and Timing
• /
• 제6권4호
• /
• pp.211-221
• /
• 2017

Ellipsodially referenced survey (ERS) is considered as one of the challenging issues in the hydrographic surveys due to the fact that the bathymetric data collected by this technique can be readily transformed either to the geodetic or the chart datum by application of some geoscientific models. Global Navigation Satellite Systems (GNSS) is a preferred technique to determine the ellipsoidal height of a vessel reference point (RP) because it provides cost-effective and unprecedentedly accurate positioning solutions. Especially, the GNSS-derived heights include heave and dynamic draft of a vessel, so as for the reduced bathymetric solutions to be potentially free from these corrections. Although over the last few decades, differential GNSS (DGNSS) has been widely adopted in the bathymetric surveys, it only provides limited accuracy of the vertical component. This technical barrier can be effectively overcome by adopting the so-called GNSS carrier phase (CPH) based techniques, enhancing accuracy of the height solution up to few centimeters. From the positioning algorithm standpoint, the CPH-based techniques are categorized under absolute and relative positioning in post-processing mode; the former is precise point positioning (PPP) correcting errors by the global or regional models, the latter is post-processed kinematic positioning (PPK) that uses the differencing technique to common error sources between two receivers. This study has focused on assessment of achievable accuracy of the ellipsoidal heights obtained from these CPH-based techniques with a view to their applications to hydrographic surveys where project area is, especially, few tens to hundreds kilometers away from the shore. Some field trials have been designed and performed so as to collect GNSS observables on static and kinematic mode. In this paper, details of these tests and processed results are presented and discussed.

• Journal of Periodontal and Implant Science
• /
• 제25권2호
• /
• pp.341-356
• /
• 1995

The purpose of this study was to evaluate the effect of demineralized freeze dried bone and demineralized bone gel with guided tissue regeneration treatment around titanium implants with dehisced bony defects and also evaluate space maintaining capacity of demineralized bone gel type and DFDB powder type under e-PTFE membrane. In 3 Beagle dogs, mandibular premolar was extracted and four peri-implant osteotomies were formed for dehiscence. After insertion of implants, the four peri-implant defects were treated as follows. 1) In control group. no graft material and barrier membrane were applied. 2) In experimental group.1, the site was covered only with the e-PTFE membrane. 3) In experimental group 2,received DFDB powder and covered by the e-PTFE membrane. 4) In experimental group 3, demineralized bone gel and e-PTFE membrane were used. By random selection, animals were sacrificed at 4, 8, 12 weeks. The block sectioned specimens were prepared for decalcified histologic evaluation(hematoxylin and eosin staining) and undecalcified histologic evahiation(Von Kossa's and toluidine blue staining) with light microscopy. The results of this study were as follows. 1) In control group, there was a little new bone formation and connective tissue was completely filled in the defect area. 2) Experimental group 1 showed lesser quantity of bone formation as compared to the bone grafted group. Thin vertical growth of new bone formation around implant fixture was shown. 3) Experimental group 2 showed thick bucco-lingual growth of new bone formation and grafted bone particles were almost resorbed in 12 week group. 4) In experimental group 3, most grafted bone particles were not resorbed in 12 week group and thick bucco-lingual bone formation was shown in dehisced defect base area. 5) There was no remarkable differences in space making capacity and new bone formation procedure between demineralized freeze-dried bone powder type and demineralized bone gel type.

• 한국화재소방학회논문지
• /
• 제30권6호
• /
• pp.84-91
• /
• 2016

물품이 수직 집약적인 형태로 적재되는 랙크식 창고는 화재발생 시 화염의 급속한 상승으로 인해 그 피해가 매우 심각하다. 이에 ESFR 및 In-Rack 스프링클러, 수직 및 수평차단막 등, 다양한 소화설비 적용을 통해 화재확산 억제에 노력하고 있으나 랙크의 크기 및 적재밀도, 적재물품의 종류 등, 매우 다양한 구성조건으로 인해 적절한 소화설비 선정에 어려움이 있다. 이에 본 연구에서는 현장조사 및 설문조사 등을 통해 국내 랙크식 창고 실정을 반영한 표준랙크를 제작하였으며, 발화위치 조건에 따른 화재특성 확인을 위해 실규모화재시험을 수행하였다. 이를 통해 도출된 화재확산속도는 향후, 개발 및 적용 예정 소화설비들의 성능비교를 위한 기초자료로서 유용하게 활용될 것으로 기대한다.

• 환경영향평가
• /
• 제20권4호
• /
• pp.539-555
• /
• 2011

Newly constructed, high-rise dense building areas by urban development can cause changes in local wind fields. Wind fields were analyzed to assess the impact on the local meteorology due to the land use changes during the urban redevelopment called "Eunpyeong new town" in north-western Seoul using CFD_NIMR_SNU (Computational Fluid Dynamics, National Institute of Meteorological Research, Seoul National University) model. Initial value of wind speed and direction use analysis value of AWS (Automatic Weather Station) data during 5 years. In the case of the pre-construction with low rise built-up area, it was simulated that the spatial distribution of horizontal wind fields depends on the topography and wind direction of initial inflow. But, in the case of the post-construction with high rise built-up area, it was analyzed that the wind field was affected by high rise buildings as well as terrain. High-rise buildings can generate new circulations among buildings. In addition, small size vortexes were newly generated by terrain and high rise buildings after the construction. As high-rise buildings act as a barrier, we found that the horizontal wind flow was separated and wind speed was reduced behind the buildings. CFD_NIMR_SNU was able to analyze the impact of high-rise buildings during the urban development. With the support of high power computing, it will be more common to utilize sophisticated numerical analysis models such as CFD_NIMR_SNU in evaluating the impact of urban development on wind flow or channel.