Experimental Investigation and Numerical Analysis to Develop Low-Energy Large-Midwater Trawls     

Jihoon LEE  Taeho KIM  Chun-Woo LEE  Subong PARK 《海洋工程》2017,(6):700-708

Fuel consumption in fisheries is a primary concern because of its effects on the environment and the costs incurred by fishermen. Many studies have been conducted to reduce the fuel consumption in fishing operations. Fuel consumption due to fishing gear during a fishing operation is generally related to the hydrodynamic resistance on the gear. This means that fuel consumption is proportional to the drag created by the towing speed. Based on numerical methods, this study suggests a new approach to reduce fuel consumption in fisheries. The results of the simulation are in good agreement with those of model experiments. The total as well as partial resistance forces on the gear are calculated by simulation. The simulation results suggest improved materials and gear structure for reducing the hydrodynamic forces on the gear while maintaining gear performance. The method for assessing the gear performance involves measuring the height and width of the net mouth. Furthermore, this study investigates the efficiency of a low-energy trawl from an economic point of view. The findings of this study will be useful in reducing greenhouse gas (GHG) emissions in fishing operations, and thereby contribute toward lowering fishing costs by saving fuel.  相似文献   

Climate variabilities of sea level around the Korean Peninsula   总被引：1，自引：0，他引：1  

Yong-Hoon YOUN  Im Sang OH  Young-Hyang PARK  Ki-Hyun KIM 《大气科学进展》2004,21(4):617-626

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An analysis of the radar backscatter from oil-covered sea surfaces using moment method and Monte-Carlo simulation: preliminary results     

YANG Chan-Su  PARK Seong-Min  OH Yisok  OUCHI Kazuo 《海洋学报(英文版)》2013,32(1):59-67

An analysis of the radar backscattering from the ocean surface covered by oil spill is presented using a microwave scattering model and Monte-Carlo simulation. In the analysis, a one-dimensional rough sea surface is numerically generated with an ocean waveheight spectrum for a given wind velocity. A two-layered medium is then generated by adding a thin oil layer on the simulated rough sea surface. The electric fields backscattered from the sea surface with two-layered medium are computed with the method of moments (MoM), and the backscattering coefficients are statistically obtained with N independent samples for each oil-spilled surface using the Monte-Carlo technique for various conditions of surface roughness, oil-layer thickness, frequency, polarization and incidence angle. The numerical simulation results are compared with theoretical models for clean sea surfaces and SAR images of an oil-spilled sea surface caused by the Hebei (Hebei province, China) Spirit oil tanker in 2007. Further, conditions for better oil spill extraction are sought by the numerical simulation on the effects of wind speed and oil-layer thickness at different incidence angles on the backscattering coefficients.  相似文献   

TEMPORAL AND SPATIAL CHARACTERISTICS OF RAINFALL IN THE NAM RIVER DAM BASIN OF KOREA     

J. I. PARK  V. P. SINGH 《水文研究》1996,10(9):1155-1171

An investigation into rainfall variability in time and space in the Nam River dam basin of Korea is made with the use of the coefficient of variation and the correlation coefficient. The Nam River dam basin is a small mountainous watershed where wind direction and orography are the dominant influences on the pattern and distribution of rainfall. Rainfall distribution was found to vary with elevation, position, wind direction and distance from a reference station. The results of this study can be used in the design of rain gauge network, hydrological forecasting and for other applications in the Nam River dam basin.  相似文献   

Antiproliferative and apoptosis-inducing potential of 3β-hydroxy-△5-steroidal congeners purified from the soft coral Dendronephthya putteri     

Thilina U.JAYAWARDENA  Won Woo LEE  I.P.Shanura FERNANDO  K.K.Asanka SANJEEWA  Lei WANG  Tee Gee LEE  Young Jin PARK  Chang-ik KO  You-Jin JEON 《中国海洋湖沼学报》2019,(4)

The exploration and identification of antiproliferative phytochemicals have received increased attention in medicinal chemistry.In particular,research focused on the toxicology of marine natural products has increased in recent years.Terpenoids,among many secondary metabolites,have been demonstrated to act as effective anticancer agents.Soft corals,a group of marine invertebrates,produce a variety of terpenoids with biofunctional properties.The current study presents the extraction,purification,and identification of sterol congeners from the soft coral Dendronephthya putteri.The method involves 50%chloro form-methanol extraction,polar column fractionation,and analy sis through GC-MS~n.Do se-dependent antiproliferative activity was observed within the sterol-rich fraction(DPCMH 2-4),which consisted of3β-hydroxy-A5-steroidal congeners.This fraction inhibited the growth of HL-60 and MCF-7 cells with IC_(50) values of 25.27±1.43 and 22.81±0.15 μg/mL,respectively.Apoptotic body formation,DNA damage,cell cycle arrest,and apoptotic cell signaling pathway activation were also observed,reinforcing the dosedependent antiproliferative and apoptosis-inducing activity of 3β-hydroxy-A5-steroidal congeners.To our knowledge,this is the first report of anticancer agent identification from the soft coral D.putteri.Based on the observations,these steroidal congeners are promising candidates for the development of anticancer drugs.  相似文献   

Trilobite Biostratigraphy of the lower Paleozoic (Cambrian–Ordovician) Joseon Supergroup, Taebaeksan Basin, Korea   总被引：1，自引：0，他引：1  

CHOI Duck K.  LEE Jeong Gu  LEE Seung-Bae  PARK  Tae-Yoon S.  HONG Paul S. 《《地质学报》英文版》2016,90(6):1976-1999

In Korea,trilobites are among the most intensively studied fossil groups in the past century and provide invaluable information about lower Paleozoic stratigraphy,paleogeography,and tectonics of the Korean Peninsula. Trilobites occur in the lower Paleozoic Joseon Supergroup of the Taebaeksan Basin which was part of the Sino-Korean Craton in the Paleozoic. The Joseon Supergroup is divided into the Taebaek,Yeongwol,and Mungyeong groups. The Taebaek and Yeongwol groups are richly fossiliferous,while the Mungyeong Group is poorly fossiliferous. Contrasting trilobite faunal contents of the Taebaek and Yeongwol groups resulted in two separate biostratigraphic schemes for the Cambrian–Ordovician of the Taebaeksan Basin. A total of 22 biozones or fossiliferous horizons were recognized in the Taebaek Group; 19 zones were established in the Yeongwol Group; and four biozones were known from the Mungyeong Group. These trilobite biozones of the Taebaeksan Basin indicate the Joseon Supergroup ranges in age from the Cambrian Series 2 to Middle Ordovician and can be correlated well with the formations of North China,South China,and Australia.  相似文献   

Global parameter estimation of the Cochlodinium polykrikoides model using bioassay data     

CHO Hong-Yeon  PARK Kwang-Soon  KIM Sung 《海洋学报(英文版)》2016,35(2):39-45

Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide(a.k.a algal bloom) model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%–50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly required.As opposed to the bioassay data, it is necessary because the bioassay data have limitations in terms of the in-situ coastal conditions.  相似文献   

韩亚航空公司航空监视和监控系统的设计与实现     

袁子翔  PARK Dong-Il 《测绘与空间地理信息》2017,40(Z1)

近些年来,民用航空事业飞速发展,随着航空公司规模的扩大、业务的扩展,竞争也日益激烈.航空运行控制以及自然灾害监控是航空公司运营的核心,直接关系到航空公司的安全生产与核心价值,过去人工监控和各部门分散的计算机管理方式显然已经无法适应航空运行控制的新要求.本文介绍了韩亚航空公司航空监视和监控系统的设计与开发过程,给出了系统的结构设计及功能设计,论述了航空监视和监控系统的组成及其对民航安全运营的促进作用.  相似文献   

The preservation potential of some recent stromatolites   总被引：3，自引：0，他引：3  

ROBERT K. PARK 《Sedimentology》1977,24(4):485-506

Stromatolites are laminated organo-sedimentary structures, generally compared to present day blue-green algal mats. Their morphology, species composition and overall extent are largely governed by the amount of wetting, although other factors such as competition, predation and desiccation, also contribute. The Trucial Coast mats are essentially intertidal. Stromatolite accretion rates in this area are of the order of 0·2 mm p.a. but lamina growth is far from regular. The area is also characterized by the development of evaporites, especially gypsum which proves to be an important agent of mat destruction. The growth of crystals causes disruption within the upper portions of the stromatolite section with the result that none of the upper intertidal mat forms are preserved. Other agencies of destruction include bacterial decay, desiccation and dehydration, and compaction under burial which may depress and deform the original mat relief. Decay results in the almost total loss of cellular contents, only a few empty sheaths and the pigment surviving into the fossil record. Preservation may be effected via (a) burial or (b) lithification. However, few modern algal mat structures bear any resemblance to fossil stromatolite heads with the exception of those from Shark Bay. From this, one might infer that pene-contemporaneous lithification is a prerequisite for their preservation.  相似文献   

Incorporating Cellular Automata simulators as analytical engines in GIS   总被引：2，自引：0，他引：2  

SOOHONG PARK  DANIEL F WAGNER 《Transactions in GIS》1997,2(3):213-231

Contemporvy GIS suffer from a variety of problems. These include poor ability to handle dynamic spatial models, poor performance for many operations, and poor handling of the temporal dimension. Cellular Automata (CA) are dynamic mathematical systems based on discrete time and space. While CA have many similarities to GIS, and indeed excel in many areas in which GIS are deficient, they cannot themselves be considered as GIS since they lack the necessary sophisticated Capabilities in data input, data storage and retrieval, and data output. However, the advantages of CA in data analysis and modelling are significant. In order to exploit fully the advantages of each system - GIS and CA - we have developed a methodology and prototype system for coupling GIS and CA, in which the CA serves as an alternative analytical engine for the GIS. In the prototype system, spatial, temporal (i.e. time series), and spatio-temporal filters as well as spatial diffusion operators are developed. In addition, the integrated system provides a flexible framework for the programming and running of dynamic spatial models. We conclude that CA represent a viable alternate analytical engine for GIS and provide increased ability for dynamic spatial modelling within GIS.  相似文献