• 한국해양학회지
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• v.20 no.2
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• pp.1-9
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• 1985

A simple analytic model of the sea surface temperature(SST) is developed in order to understand the effects of the Asian monsoon and the Kuroshio on the annual variations of SST by the Asian monsoon is almost in phase with the incoming radiation whereas that by the Kuroshio is out of phase with the incoming radiation. In the Yellow Sea, due to the heat advection by the Asian monsoon, the yearly mean SST is low and the annual range of SST exceeds 20$^{\circ}C$. The annual range of SST in the northwestern Japan Sea is large because of the combined effects of the Asian monsoon and the cold water advection. In the Kuroshio and in the Tsushima Current regions, the annual range of SST is small and the mean SST is high due to the heat advection by warm currents.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.95-101
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• 2010

The aim of this study was to detect longitudinal alterations on lumbar vertebral trabecular bone quality (microarchitecture and degree of mineralization) and bone mineral density (BMD) during pregnancy Virginal eighteen mice were used. Then, twelve mice were mated. Mice lumbar vertebrae were scanned before mate, at 7 days of pregnancy (early pregnancy, 6 mice) and immediately after delivery (late pregnancy, 6 mice) by using in-vivo micro-computed tomography Structural parameters, degree of mineralization and BMD were measured. During early pregnancy, there were no significant alterations on structural parameters, degree of mineralization and BMD. At late pregnancy, Tb.Th (11.8%) and BMD (12.7%) were significantly decreased and Tb.N (6.3%), Tb.Pf (43.0%) and BS/BV (15.1%) were significantly increased (p<0.05). Additionally, the lower degree of mineralization was increased, although, the higher degree of mineralization was decreased. These results indicated that the quality and BMD might be not affected during early pregnancy. At late pregnancy, however the bone quality and BMD were likely to be negatively affected.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.444-451
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• 2009

Purpose: The aim of present study is to detect longitudinal alterations of mechanical characteristic determined by bone quality (microarchitecture and degree of mineralization) on femur trabecular bone due to metastatic bone tumor Materials and Methods: Each 6 female SD rats (12 weeks old, approximate 250g) were allocated in SHAM and TUMOR Group. W256 (Walker carcinosarcoma 256 malignant breast cancer cell) was injected into the right femur (intraosseous injection) in TUMOR Group, whereas 0.9% NaCl (saline solution) was injected in SHAM Group. The right hind limbs of all rats were scanned by in-vivo micro-CT to acquire structural parameters, bone mineral density, X-ray attenuation and bone mineralization distribution at 0 week and 4 weeks after surgery. Results: BMD, BV/TV and Tb.N of trabecular bone in TUMOR group were markedly decreased (26%, 11% and 23%) while those in SHAM group were significantly increased (34%, 48% and 11%) (p<0.05). BS/BV, Tb.Sp and SMI in TUMOR group were significantly increased (-16%, 38% and 2%) compared with those in SHAM group (-33%, 12% and -16%) (p<0.05). Additionally, bone mineralization in TUMOR group significantly decreased while those in SHAM group was significantly increased (p<0.05). Conclusion: It is identified that how much bone microarchitecture and mineralization are diminished due to the metastatic bone tumor. The results may be helpful to prediction of fracture risk by metastatic bone tumor.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.85-93
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• 1985

An initial attempt was made to investigate sea surface topography in the East China Sea using the SEASAT-A altimeter data. Over the study area for the two major typhoon surges generated during the SEASAT mission, space and time variability of the shallow water tides, meteorological effects and earth tides were removed from the altimetric measurements using the systematic procedures which include the two-dimensional sea model of the East China Sea. The analysis of ten flights over the ground track for the typhoon periods were presented and discussions were made for further studies. This initial study has been undertaken in association with the programme of establishment of systematic altimeter data reduction system for the study of shelf dynamics in the East China Sea.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1605-1609
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• 2010

CGCM3.1 SRES B1 시나리오의 2D 변수들을 입력값으로 인공신경망 모형을 이용한 스케일 상세화기법으로 강부식(2009)은 소양강댐 유역의 월 누적강수 경향분석을 실시하였다. 원시 GCM 시나리오를 스케일 상세화 시키기 위한 기법의 하나로 인공신경망 모형을 사용할 수 있는데, 이 경우 GCM에서 모의되는 강수플럭스, 해면기압, 지표면 근처에서의 일 평균온도, 지표면 근처에서의 일평균온도, 지표면으로부터 발생하는 잠열플럭스 등과 같은 22개의 변수를 잠재적인 예측인자로 사용하여 신경망을 구성하게 된다. 입력변수세트의 구성은 인공신경망의 계산 효율을 좌우하는 중요한 요소라 할 수 있다. 본 연구에서는 변수의 물리적 특성을 고려하여 순차적인 변수선택을 통한 신경망 입력변수 세트를 구성하고 입력세트 간의 학습성과 비교를 통하여, 최적 입력변수 선정 및 신경망의 학습효과를 높일 수 있는 방법에 대해 연구하였다. 물리적 상관성이 높다고 판단되는 GCM_Prec, huss, ps를 입력변수로 하여 순차적인 케이스를 학습해본 결과 huss와 ps를 입력변수로 하는 케이스에 대해서 적은 오차와 높은 상관성을 보였다, 또한, 신경망의 학습 효과를 높이기 위해 홍수기와 비홍수기로 구분하여 학습한 결과 홍수기와 비홍수기로 구분하여 신경망을 구성하였을 경우가 향상된 모의값을 나타내었다. 기후변화모의자료는 CCCma(Canadian Center for Climate Modeling and Analysis)에서 제공되는 CGCM3.1/T63 20C3M 시나리오를 사용하였으며, 관측값으로는 AWS에서 제공된 일 누적강수를 사용하였다. 인공신경망의 학습기간은 1997년부터 2000년이며, 검증기간은 2001년부터 2004년으로 구성하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1121-1130
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• 2009

In order to investigate the offshore wind resources, the measured data from the QuikSCAT satellite was analyzed from Jan 2000 to Dec 2008. QuikSCAT satellite is a specialized device for a microwave scatterometer that measures near-surface wind speed and direction under all weather and cloud conditions. Wind speed measured at 10 m above from the sea surface was extrapolated to the hub height by using the power law model. It has been found that the high wind energy prevailing in the south sea and the east sea of the Korean peninsula. From the limitation of seawater depth for piling the tower and archipelagic environment around the south sea, the west and the south-west sea are favorable to construct the large scale offshore wind farm, but it needs efficient blade considering relatively low wind speed. Wind map and monthly variation of wind speed and wind rose using wind energy density were investigated at the specified positions.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.2
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• pp.63-75
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• 2018

This study analyzed the long-term linear trends of the sea surface height around the Korea marginal seas for the period of 1993~2016 by using quantile regression. We found significant difference about 2~3 mm/year for the linear trend between OLS (ordinary least square) and median (50%) quantile regression especially in the Yellow Sea, which is affected by extreme events. Each area shows different trend for each quantile (lower (1%), median (50%) and upper (99%)). Most areas of the Yellow Sea show increasing trend in both low and upper quantile, but significant "upward divergence tendency". This implies that significant increasing trend of upper quantile is higher than that of lower quantile in this area. Meanwhile, South Sea of Korea generally shows "upward convergence tendency" representing that increasing trend of upper quantile is lower than that of lower quantile. This study also confirmed that these tendencies can be eliminated by removing major tidal components from the harmonic analysis. Therefore, it is assumed that the regional characteristics are related to the long term change of tide amplitude.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.80-80
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• 2016

GPS로 대표되는 위성항법시스템(GNSS : Global Navigation Satellite System)은 지구 주위를 돌면서 연속적으로 항법신호를 보내고 있다. 그 중 지구표면으로부터 반사되는 항법신호를 수신하고 해석함으로써 지구표면에 관한 정보를 취득할 수가 있다. GPS로 대표되는 항법신호는 L밴드를 사용하기 때문에 토양수분의 변화 등에 대한 반사강도의 감도가 비교적 높다고 알려져 있으며, 토양수분 측정 등에 사용할 수 있다. 뿐만 아니라 경량화, 소형화하기 쉬운 점, 능동적 마이크로웨이브 리모트센싱시스템(Active Microwave Remote Sensing System)과 달리 스스로 신호를 발사하지 않기 때문에 관측의 스텔스성(Stealth)dl 뛰어난 점 등의 장점을 가지고 있다. 또한 향후 10년 이내에 준천정위성(QZSS), Galileo, COMPAS, IRNSS 등 많은 위성항법시스템이 본격 운용되어 GPS와 함께 120기 정도의 항법위성이 항법신호를 송신할 예정이므로 이용 가능성은 크게 늘어날 것으로 기대된다.한편, 항법위성을 이용한 바이스테이틱 리모트센싱은 반사파의 강도가 상당히 미약하기 때문에 정량적 계측모델의 구축은 미미한 상태이다. 즉, 지상 타워에서의 관측, 항공기에서의 관측, 소형 위성에서의 관측 등이 수행되고 있으나, 타워관측과 같이 지상의 거의 동일한 장소를 계속적으로 관측하는 경우를 제외한 기존의 연구에서는 토지의 피복상황이나 토양수분 등의 상관관계를 제시하는 수준으로써 정량적인 계측방법은 아직 확립되어 있지 않다. 이러한 관점에서 본 연구에서는 GPS위성으로부터의 항법신호를 이용하여 지구표면에 관한 정보를 얻는 바이스테이틱 리모트센싱(Bi-static Remote Sensing) 기술을 바탕으로 육지면과 해면의 판별에 신호특성이 어떻게 유효한가를 실험적으로 밝혔다. 이러한 기술은 토양수분 측정 등 수자 원인자를 추출하는데 유용할 뿐만 아니라 수면의 고도 측정, 해상풍 산출 등에도 응용 가능하다.

• Ocean and Polar Research
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• v.43 no.2
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• pp.53-63
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• 2021

Changes in a marine environment have a broad socioeconomic implication on fisheries and their relevant industries so that there has been a growing demand for the medium-range (months to years) prediction of the marine environment Using a medium-range ocean prediction model (Ocean Mid-range prediction System, OMIDAS) for the northwest Pacific, this study attempted to assess seasonal difference in the mid-range predictability of the sea surface temperature (SST), focusing on the Korea seas characterized as a complex marine system. A three-month re-forecast experiment was conducted for each of the four seasons in 2016 starting from January, forced with Climate Forecast System version 2 (CFSv2) forecast data. The assessment using relative root-mean-square-error was taken for the last month SST of each experiment. Compared to the CFSv2, the OMIDAS revealed a better prediction skill for the Korea seas SST, particularly in the Yellow sea mainly due to a more realistic representation of the topography and current systems. Seasonally, the OMIDAS showed better predictability in the warm seasons (spring and summer) than in the cold seasons (fall and winter), suggesting seasonal dependency in predictability of the Korea seas. In addition, the mid-range predictability for the Korea seas significantly varies depending on regions: the predictability was higher in the East Sea than in the Yellow Sea. The improvement in the seasonal predictability for the Korea seas by OMIDAS highlights the importance of a regional ocean modeling system for a medium-range marine prediction.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.51-61
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• 2023

Sound can travel a long distance in the ocean; hence, acoustic instruments have been widely used for ocean observations in various fields such as bathymetric survey, object detection, underwater communication, and current measurements. Herein we introduce a pressure-recording inverted echo sounder (PIES) which is one of the most powerful instruments, moored at seafloor for ocean observation in physical oceanography. The PIES can measure various kinds of oceanic phenomena (currents, mesoscale eddies, internal waves, and sea surface height variabilities) and support acoustic telemetry and pop-up data shuttle (PDS) system for remote data acquisition. In this paper, we review uses of PIES and describe present and prospective system of PIES including remote data acquisition toward (quasi) real-time data recovery.