• Proceedings of the KSR Conference
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• 2003.05a
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• pp.343-348
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• 2003

As one of countermeasures for vibration and noise source which come from train operation in subway system, the heavy-weighted tunnel structure and the low-vibration track design have been adopted. In recent the low-vibration concrete track have been constructed to enhance the maintenance effectiveness as well as the reduction of vibration. This paper is explaining and evaluating of the characteristics of vibration and its effects comparing to tile ballast track, concrete track, and full surface supported floating slab track installed on Express bus terminal in Seoul subway No. 7 line.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.106-107
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• 2016

Rolling motion of floating body might upset the body, make crews and passengers exhausted and/or apply forces to the structure to cause damage. Therefore for almost ships bilge keels are equipped, in special case fin stabilizer or gyroscope may be installed. This paper suggests the Anti-rolling pendulum to reduce roll motion to act the similar role with anti-rolling tank. The device suggested has more effective than the anti-rolling tank with 1/6 volume of the tank.

• Journal of Korea Water Resources Association
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• v.33 no.2
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• pp.181-193
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• 2000

This paper presents the flow and the suspended sediment movement over ripples for oscillatory flows. A new numerical model system is developed, and applied to a laboratory experimental condition of regular waves and a fictitious condition of irregular waves. The flow field is obtained from a programme proposed by Kim et. al.(1994), which is a modified version of SOLA based on SMAC scheme. The sub-model solves the continuity and Reynolds momentum equations in the x-z plane. The wave orbital velocities, shear stresses, and pressure are all reasonably reproduced by the model. The model results on the vertical velocity component show good agreement with the measurements. The suspended sediment transport sub-model is newly set up to solve the advection-diffusion equation of suspended sediment using a split method, and involving a special shear entrainment from the whole ripple surface. The calculated suspended sediment concentrations for regular waves show reasonable agreement with measurements at Deltaflume. The model results for random waves show that the suspended sediment concentration is higher than those for regular waves and that the sediment diffuses higher than for regular waves with the significant wave height and the peak wave period of the irregular waves.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.157-165
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• 2010

In June 2010, Geostationary Ocean Color Imager (GOCI), the world's first ocean color observation satellite will be launched. GOCI is planned for use in real-time monitoring of the ocean environment around Korean Peninsula by daily analysis of ocean environment measurements of chlorophyll concentration, dissolved organic matter, and suspended sediments taken eight times per day for seven years. GOCI primary data will support a fishery information service and red tide forecasting, and ocean climate change research. In this paper, the development background of GOCI, user requirements, GOCI architecture, and the GOCI on-orbit operational concept are explained.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.361-368
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• 2016

A ship's rolling motion can make crew and passengers sick and/or apply forces to the structure that cause damage.. Therefore bilge keels are equipped in most ships for anti-rolling. In special cases, anti-rolling tanks (ARTs), fin stabilizers, or gyroscopes can be installed. However, ARTs require a large area to install, and fin stabilizers and gyroscopes are costly to install and expensive to operate. This paper suggests a Anti-rolling pendulum (ARP) to reduce roll motion. ARPs acts like ARTs. However, the ARP has a circular shaped guidance arc instead of the string or wire of a simple pendulum. The device suggested has about 1/ 8 the weight and 1/ 6 the volume of a ART and is more effective. This study derives the nonlinear and linear differential equations of system motion.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.189-207
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• 2010

Several ocean color algorithms have been developed for GOCI (Geostationary Ocean Color Imager) using in-situ bio-optical data sets. These data sets collected around the Korean Peninsula between 1998 and 2009 include chlorophyll-a concentration (Chl-a), suspended sediment concentration (SS), absorption coefficient of dissolved organic matter ($a_{dom}$), and remote sensing reflectance ($R_{rs}$) obtained from 1348 points. The GOCI Chl-a algorithm was developed using a 4-band remote sensing reflectance ratio that account for the influence of suspended sediment and dissolved organic matter. The GOCI Chl-a algorithm reproduced in-situ chlorophyll concentration better than the other algorithms. In the SeaWiFS images, this algorithm reduced an average error of 46 % in chlorophyll concentration retrieved by standard chlorophyll algorithms of SeaWiFS. For the GOCI SS algorithm, a single band was used (Ahn et al., 2001) instead of a band ratio that is commonly used in chlorophyll algorithms. The GOCI $a_{dom}$ algorithm was derived from the relationship between remote sensing reflectance band ratio ($R_{rs}(412)/R_{rs}(555)$) and $a_{dom}(\lambda)$). The GOCI Chl-a fluorescence and GOCI red tide algorithms were developed by Ahn and Shanmugam (2007) and Ahn and Shanmugam (2006), respectively. If the launch of GOCI in June 2010 is successful, then the developed algorithms will be analyzed in the GOCI CAL/VAL processes, and improved by incorporating more data sets of the ocean optical properties data that will be obtained from waters around the Korean Peninsula.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.2
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• pp.54-58
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• 1995

1957년 인공위성의 효시가 되는 스프티닉 1호 발사이래 1994년 현재까지 약 4,000회로 추정되는 각종통신 측지 첩보 및 실험 위성 등의 발사로 지구 적도상공 36,000Km의 정지궤도 이하의 공간에는 수많은 퇴역위성, 소아마비위성(부분기능고장위성)과 더불어 발사로켓트 상단의 위성 격납용기인 내연성의 훼 어링(Fairing)의 탈락파련(Fragment)등으로 혼재된 부유물은 약 4,000톤으로 예상되며 이중 95%가 쓸모 없는 우주 쓰레기에 해당된다고 보고 있다. 여기서, 우주쓰레기의 정의는 "현재와 장래에도 유용한 목적에 이용되지 못하는 인공물체"로서 크기 로는 10여미터로 부터 산화된 연료 분사개스의 수미크론의 분진으로까지 광범위하다. 그러나, 본고에서는 우주 활동에 악영향을 끼칠수 있는 대량으로 산재된 밀리미터에서 쎈티미터의 크 기의 고속 운동 에너지를 지닌 쓰레기 조각(Debris)을 고찰해 보고자 한다.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.756-762
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• 2004

Up to now, the only way is Floating Slab Track System, which cuts off vibration by installing spring between concrete slab and ground for the lines of particularly requiring attenuating vibration. The weak point of Floating Slab Track System is large increase of construction cost because normally the structure is getting bigger. In regards to this matter, Floating Rail Track System has been developed, which cuts off vibration by floating the first cause of vibration rail, and the system is in operation. In the thesis, the application of new attenuating vibration track system has been confirmed by studying theoretical background of Floating Rail Track System and evaluating dynamic deflection of track and attenuating of noise and vibration performance through various measurements from laboratory tests and site inspection.

• KIISE Transactions on Computing Practices
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• v.23 no.1
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• pp.74-79
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• 2017

The Geostationary Ocean Color Imager (GOCI), the world's first ocean color sensor operated in a geostationary orbit, can be utilized to mitigate damages by monitoring marine disasters in real time such as red tides, green algae, sargassum, cold pools, typhoons, and so on. In this paper, we described a methodology and procedure for processing GOCI data in order to maximize its utilization potential. The GOCI data processing procedure is divided into data reception, data processing, and data distribution. The kinds of GOCI data are classified as raw, level 1, and level 2. "Raw" refers to an unstructured data type immediately generated after reception by satellite communications. Level 1 is defined as a radiance data type of two dimensions, generated after radiometric and geometric corrections for raw data. Level 2 indicates an ocean color data type from level-1 data using ocean color algorithms.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.251-262
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• 2010

In order to provide quantitative control of the standard products of Geostationary Ocean Color Imager (GOCI), on-board radiometric correction, atmospheric correction, and bio-optical algorithm are obtained continuously by comprehensive and consistent calibration and validation procedures. The calibration/validation for radiometric, atmospheric, and bio-optical data of GOCI uses temperature, salinity, ocean optics, fluorescence, and turbidity data sets from buoy and platform systems, and periodic oceanic environmental data. For calibration and validation of GOCI, we compared radiometric data between in-situ measurement and HyperSAS data installed in the Ieodo ocean research station, and between HyperSAS and SeaWiFS radiance. HyperSAS data were slightly different in in-situ radiance and irradiance, but they did not have spectral shift in absorption bands. Although all radiance bands measured between HyperSAS and SeaWiFS had an average 25% error, the 11% absolute error was relatively lower when atmospheric correction bands were omitted. This error is related to the SeaWiFS standard atmospheric correction process. We have to consider and improve this error rate for calibration and validation of GOCI. A reference target site around Dokdo Island was used for studying calibration and validation of GOCI. In-situ ocean- and bio-optical data were collected during August and October, 2009. Reflectance spectra around Dokdo Island showed optical characteristic of Case-1 Water. Absorption spectra of chlorophyll, suspended matter, and dissolved organic matter also showed their spectral characteristics. MODIS Aqua-derived chlorophyll-a concentration was well correlated with in-situ fluorometer value, which installed in Dokdo buoy. As we strive to solv the problems of radiometric, atmospheric, and bio-optical correction, it is important to be able to progress and improve the future quality of calibration and validation of GOCI.