• 한국해양공학회지
• /
• 제17권3호
• /
• pp.13-20
• /
• 2003

This research aims at investigation of accuracy potential of RTK(Real-Time Kinematic) GPS in combination with Echo Sounder(E/S) for the coastal mapping. Apart from this purpose, the accuracy of ambiguity resolution with the OTF(On The Fly) method was tested with respect to the initialization time. The result shows that the accuracy is better than 1cm with 5-minute initialization in the distance of 10km baseline. The seaside topography was measured by the RTK GPS only, on the other hand the seafloor topography was surveyed in combination of RTK GPS and E/S. Comparing to the volume of seaside measured by RTK GPS and digital topographical map, the difference of only $2\%$ was achieved. This indicates that the coastal mapping. As a result, it has been revealed that every possible noise in surveying could be corrected and the accuracy could be improved. The accuracy of GPS data acquired in real time was as good as that acquired by post processing. It is expected that it will be useful for the analysis of coastal geographic characteristics because DTM(Digital Terrain Model) can be also constructed for the harbor reclamation, the dredging, and the variation of soil movement in a river.

• 한국해양공학회지
• /
• 제20권3호
• /
• pp.61-66
• /
• 2006

The estuary has a very complex coastline and bottom topography. Before the close of floodgate, the Keum river estuary was deposited with sediment from the Keum river, created bythe construction of the Keum river estuary dike. So, a periodical dredging is necessary to assure water depth for boat entry and departure to Kunsan port. Theof this study is to find the change of tidal current of M2tide and the topography before and after construction at the Geum River estuary dike. The change of water depth is investigated by digitizing the sea map (No.305) of Kunsan port, which was edited by National Oceanographic Research Institute. The calculated co-range and co-tidal charts of M2tide before the dike construction are similar to the observed ones. Therefore, the amplitude and phase after construction at Geum River estuary dike increases compared to before construction at Geum River estuary dike. The scour occurred in the A-A' section.

• Journal of the Optical Society of Korea
• /
• 제15권1호
• /
• pp.68-73
• /
• 2011

This study investigated, using the Orbscan II topography system, the influence of age and sex related changes on the corneal thickness and anterior corneal curvature, more specifically the fine structure of the cornea, in a Korean young population. The Orbscan II topography system is a computer-assisted slit-beam scanning technology that can map the anterior section of the cornea. The mean central corneal thickness of all subjects was $547.532{\pm}44.529\;{\mu}m$. There was no statistical difference (p>0.5) in the mean central corneal thickness between males and females. Sex and age related changes in the mean central corneal thickness had no specific statistical difference (P>0.5). There was a negative correlation between the anterior corneal curvature and the central corneal thickness in all subjects, except for the twenty year olds. However, the thickness relationship between the mean central corneal and the eight paracentral corneal thicknesses had strong statistical differences in all subjects. Also age and sex related changes in the central corneal thickness and the anterior corneal curvature in all subjects had no statistically significant difference, except from 20-26 years old (p>0.05). This information could be a suitable reference basis for future studies in the young population of Asia and for the development of examination tools for corneal refractive surgery.

• 한국수자원학회논문집
• /
• 제55권10호
• /
• pp.811-821
• /
• 2022

불연속 지형 전면에 작용하는 정수압 분포에 실제 압력과 차이를 해명하는 흐름률 보정 계수를 도입하여 불연속 지형을 직접 해석하는 Hwang의 기법이 적용된 수치 모형의 정확도를 높일 수 있었다. 218개 실험 시행으로 직각 광정 위어의 월류량에 가장 적합한 계수를 결정하였으며, 이것을 별도의 두 가지 직립 광정 위어 실험과 측면 위어 부정류 실험에 적용해보니 실험과 모의에서 월류량이 서로 잘 일치하였다. 이로써 조밀한 격자로 불연속 지형을 완화하거나 내부 경계를 부여하지 않고도 직각 광정 위어와 같은 불연속 하천 구조물을 지나는 천수 흐름의 정확한 수치 모의가 가능해졌다.

• 한국산업융합학회 논문집
• /
• 제26권1호
• /
• pp.133-141
• /
• 2023

Accurate measurement of seafloor topography plays a crucial role in developing marine industries such as maritime safety, resource exploration, environmental protection, and coastal management. The seafloor topography is constructed using side scan sonar (SSS) and single beam echosounder (SBES) or multibeam echosounder (MBES), which transmit and receive ultrasound waves through a device attached to a marine survey vessel. However, the use of a sonar system is affected by noise pollution areas, and the single beam has a limited scope of application. At the same time, the multibeam is mainly applicable for depth observation. For these reasons, it is difficult to determine the boundaries and areas of seafloor topography. Therefore, this study proposes a method to improve the backscatter data of multibeam echosounder, which has a relationship with the seafloor quality, by using digital image processing to classify the shape of the underwater surface.

• 한국지반환경공학회 논문집
• /
• 제13권5호
• /
• pp.59-68
• /
• 2012

본 연구의 목적은 홍수범람해석을 위한 하천지형 구축기법을 연구하는 것이다. 청도천을 대상으로 1:5,000수치지형도와 WMS를 통해 무료로 제공되는 DEM인 ASTER과 SRTM를 이용하여 하천지형을 구축하였으며, 범람해석에는 HEC-RAS 및 HEC-GeoRSA를 적용하였다. 빈도별 기법에 따른 홍수범람해석을 모의하였으며, 1:5,000수치지형도를 기준으로 홍수심과 홍수면적을 비교하였다. 중규모 이하 자연유역을 대상으로 기법별로 구축된 하천지형은 큰 차이가 없었으며, 범람해석시 ASTER DEM을 이용한 해석결과는 침수면적의 경우 산간지역의 경우 다소 크게 산정되었다. SRTM DEM의 경우에는 타기법에 비하여 적절한 홍수 범람해석 결과가 산정되어 향후 실무에서 활용이 가능할 것으로 기대된다.

• 한방재활의학과학회지
• /
• 제18권1호
• /
• pp.141-151
• /
• 2008

Objectives : The purpose of this study was to investigate effects of long-term taxi driving posture on the balance of musculoskelectal system. Methods : The author practiced Moire topography by using IBS-2000 for 30 male taxi drivers and general people. Then we measured difference of contour lines, difference of shoulder joint height, interval between vertical baseline of pelvis and vertical baseline of neck, ratio of thoracic curve and lumbar curve, difference of width between right and left through Moire topography. After we statistically analyzed difference of Moire topography's data between long-term employed male taxi drivers and general people. Results : 1. Taxi drivers, difference of contour lines in scapular, lumbar, gluteal region was bigger than general people and significant difference(p<0.05) was observed between subject group. 2. Taxi drivers, diference of shoulder joint height was more large than general people and significant difference(p<0.01) was observed between subject group. 3. Taxi drivers, diference of interval between vertical baseline of pelvis and vertical baseline of neck was more large than general people and significant difference((p<0.05) was observed between subject group. 4. Taxi drivers, ratio of thoracic curve was more large than general people and ratio of lumbar curve was more less than general people and significant difference(p<0.05) was observed between subject group. Conclusions : According to above results long-term taxi driving posture might cause musculoskelectal system unbalance.

• 한국측량학회지
• /
• 제37권6호
• /
• pp.507-516
• /
• 2019

토지특성조사는 토지가격비준표 작성 및 표준지와 개별지의 특성차이 비교를 통한 지가 산정 과정에서 매우 중요한 과정이다. 따라서 토지특성조사는 최대한 객관적이고 합리적이며 일관성 있게 이루어져야 한다. 그러나 현재 토지특성조사는 지자체 공무원과 감정평가사의 경험이 상당수 반영되고 있기 때문에 객관성과 일관성을 보장하기 어렵다. 본 연구에서는 현행 토지특성조사 항목 중 고저의 조사방식을 분석하여 문제를 정의하고, 고저 분류를 위해 토지의 고저 정보를 공간정보 기술 기반으로 수치화하여 이를 데이터 마이닝 기법 중 하나인 C4.5을 적용하여 고저를 분류하는 방법을 제시하였다. 서울시의 표준지 고저 조사 결과와 필지의 공간정보를 C4.5 모델에 적용한 결과에서는 기존 감정평가사의 조사 결과 약 93.5% 일치 하는 것으로 나타났다.

• 대한기계학회논문집A
• /
• 제22권4호
• /
• pp.868-878
• /
• 1998

There are recently increasing needs for precision XYZ-stage in the fields of nanotechnology, specially in AFMs(Atomic Force Microscope) and STMs(Scanning Tunneling Microscope). Force measurements are made in the AFM by monitoring the deflection of a flexible element (usually a cantilever) in response to the interaction force between the probe tip and the sample and controlling the force neasyred constant topography can be obtained. The power of the STM is based on the strong distance dependence of the tunneling current in the vacuum chamber and the current is a feedback for the tip to trace the surface topography. Therefore, it is required for XYZ-stage to position samples with nanometer resolution, without any crosscouples and any parasitic motion and with fast response. Nanometer resolution is essential to investigate topography with reasonable shape. No crosscouples and parasitic motion is essential to investigate topography without any shape distortion. Fast response is essential to investigate topography without any undesirable interaction between the probe tip and sample surface ; sample scratch. To satisfy these requirements, this paper presents a novel XYZ-stage concept, it is actuated by PZT and has a monolithic flexible body that is made symmetric as possible to guide the motion of the moving body linearly. PZT actuators have a very fast response and infinite resolution. Due to the monolithic structure, this XYZ-stage has no crosscouples and by symmetry it has no parasitic motion. Analytical modeling of this XYZ-stage and its verification by FEM modeling are performed and optimal design that is to maximize 1st natural frequencies of the stage is also presented and with that design values stage is manufactured.

• 대기
• /
• 제24권1호
• /
• pp.17-27
• /
• 2014

In this study, the observational environment for sunshine duration at Seoul and Daegu Automated Synoptic Observing Systems (ASOSs) was analyzed using a numerical model. In order to analyze the effects of topography and buildings on observational environment for sunshine duration, the model domains including the elevated building and mountainous areas around Seoul and Daegu ASOSs were considered. Three dimensional topography and buildings used as input data for the numerical model were constructed using a geographic information system (GIS) data. Solar azimuth and altitude angles calculated for the analysis period (one-week for each season in 2008) in this study were validated against those by Korea Astronomy and Space Science Institute (KASI). The starting and ending times of sunshine duration observed at ASOSs largely differed from the respective sunrise and sunset times simply calculated using solar angles and information of ASOSs' latitude and longitude, because uneven topography and elevated buildings around ASOSs cut off sunshine duration right after the sunrise and right before the sunset. The model produced the sunshine indices for Seoul and Daegu ASOSs with the time interval of one minute and the period of one week for each season and we compared the hourly averaged indices with those observed at the ASOSs. One week of which the cloudiness is lowest for each season is selected for analysis. Not only the adjacent buildings but also distant buildings and mountain cut off sunshine duration right after the sunrise and right before the sunset. The buildings and topography cutting off sunshine duration were found for each analyzing date. It was suggested that, in order to evaluate the observational environment for sunshine duration, we need to consider even the information of topography and/or building far away from ASOSs. This study also showed that the analyzing method considering the GIS data is very useful for evaluation of observational environment for sunshine duration.