• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.71-78
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• 2009

Korea Marine Environment Management Corporation (KOEM) has waste oil facilities in 13 ports to collect and treat waste oil, bilge, etc. from ships based upon the Marine Environment Management Act of Korea and MARPOL 73/78 convention. Those facilities were designed and have been operated simply to discharge water under the level 15 ppm of oil contents. However, bad smells occurred from rotten organic matters in waste water and direct discharge of harmful substances to receiving water caused civil appeals. Therefore, KOEM tried to develop new process for treatment of oily waste water from ships, which could mitigate harmful substances, save cost, calm down civil appeals and contribute to marine environment preservation. This process consists of 3 steps to remove oil contents via gravity variation at first, $O_3$ input to contact water and organism deposition by inputting condensate deposits. Then finally upper water will be discharged, and the deposited substances in the bottom will be compressed through spinning machine to transfer to the designated contractors for treatment of wastes. This is very effective and innovative in that it could reduce 3 or 4 steps compared with existing process and mitigate not only waste oil concentration but also hard resolving materials such as colloid, ABS, phosphorus, nitrogen and bad smells. This method is expected to minimize bad smells and harmful gases, to save more than 10% of maintenance cost, and to arrange the good base for garbage treatment business dealing with waste water and bad smell.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.277-286
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• 2002

Most of the problems in dealing with the tunnel construction are the uncertainties and complexities of the stress conditions and rock strengths in ahead of the tunnel excavation. The limitations on the investigation technology, inaccessibility of borehole test in mountain area and public hatred also restrict our knowledge on the geologic conditions on the mountainous tunneling area. Nevertheless an extensive and superior geophysical exploration data is possibly acquired deep within the mountain area, with up to the tunnel locations in the case of alternative design or turn-key base projects. An appealing claim in the use of artificial neural networks (ANN) is that they give a more trustworthy results on our data based on identifying relevant input variables such as a little geotechnical information and biological learning principles. In this study, error back-propagation algorithm that is one of the teaching techniques of ANN is applied to presupposition on Rock Mass Ratings (RMR) for unknown tunnel area. In order to verify the applicability of this model, a 4km railway tunnel's field data are verified and used as input parameters for the prediction of RMR, with the learned pattern by error back propagation logics. ANN is one of basic methods in solving the geotechnical uncertainties and helpful in solving the problems with data consistency, but needs some modification on the technical problems and we hope our study to be developed in the future design work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.826-833
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• 2017

It is important to localize trains precisely for the purpose of controlling them and there have been many studies designed to accomplish this without the need for wayside systems. Since trains run on fixed railway lines, it is possible to search in one direction to localize them. Moreover, it is also possible to know the shape of the line in advance. In the case of high speed trains, their speed and, therefore, their Doppler frequency is relatively high and the railway line is either linear or circular with a large radius. In this study, we utilize these features and propose a train localization method using the Doppler frequency of the signals transmitted from two points (base stations). We derive localization equations for a linear line, circular line, and mixed line (linear plus circular) respectively. Though Doppler radars are usually used to measure speed, the proposed method obtains the location information and the speed successively using the ratio of the doppler frequencies of two signals without knowing the location information or the speed. Computer simulations are performed to show the variation of the estimation error according to the train's location and the measurement error level. The conditions required to obtain the target error level and the increase in the estimation error according to the measurement error are compared between the proposed and conventional methods. The results show the superior performance and robustness of the proposed method.

• Journal of Advanced Navigation Technology
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• v.6 no.3
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• pp.195-202
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• 2002

Recently, as the range of mobile communication services is extended, the interference between adjacent base-stations is increased. Nowdays, one of the important factors causing interference is IMD (Inter-Modulation Distortion) problems. Not only active IMD but also passive IMD effects must be considered to design a CDMA system. In this study, we design and implement 7/16" DIN connectors which have a various intensity of surface illumination, thickness and quality of plating material to analyze the effects of PIMD. And propose the methods for improving the PIMD characteristics: First, it is more profitable to use the metal which has good intensity of surface illumination where most of all electric currents passes through it. Secondly, we should plate metals more than $5{\mu}m$ for RF energy enough to propagate in a medium. Thirdly, it is necessary to select a metal having high conductivity and specific heat to protect the aging phenomenon of plate material. And it is required to develop a new plating material to replace the current materials, such as the alloy of three components for cost reduction. We have to know that the plate which has intensity of surface illumination 6 S and the thickness of plating material $5{\mu}m$ satisfy the domestic PIMD specification (KTF) -150 dBc, regardless of the plate material in case of 7/16" DIN connector.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.2
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• pp.31-43
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• 1988

The Purpose of this study is to develop the rainfall-delayed response model (RDR Model) which influences the baseflow proportion of rivers as a result of the antecedent precipitation of the previous several months. The assesment of accurate baseflows in the rivers is one of the most important elements for the planning of seasonal water supply for agriculture, water resources development, hydrological studies for the availability of water and design criteria for various irrigation facilities. The Palukan river gauging site which is located in the Pulukan catchment on Bali Island, Indonesia was selected to develop this model. The basic data which has been used comprises the available historic flow records at 19 hydrologic gauging stations and 77 rainfall stations on Bali Island in the study. The methology adopted for the derivation of the RDR model was the water balance equation which is commonly used for any natural catcbment ie.P=R+(catchment losses) -R+(ET+DP+DSM+DGW). The catchment losses consist of evapotranspiration, deep percolation. change in soil moisture, and change in groundwater storage. The catchment areal rainfall has been generated by applying the combination method of Thiessen polygon and Isohyetal lines in the studies. The results obtained from the studies may be summarized as follows ; 1. The rainfall-runoff relationship derived from the water balance equation is as shown below, assuming a relationship of the form Y=AX+B. Finally these two equations for the annual runoff were derived ; ARO$_1$=0.855 ARF-821, ARF>=l,400mm ARO$_2$=0.290ARF- 33, ARF<1,400mm 2. It was found that the correction of observed precipitation by a combination of Thiessen polygons and Isohyetal lines gave good correlation. 3. Analysis of historic flow data and rainfall, shows that surface runoff and base flow are 52 % and 48% (equivalent to 59.4 mm) of the annual runoff, respectively. 4. Among the eight trial RDR models run, Model C provided the correlation with historic flow data. The number of months over which baseflow is distributed and the relative proportions of rainfall contributing in each month, were estimated by performing several trial runs using data for the Pulukan catchment These resulted in a value for N of 4 months with contributing proportions of 0.45, 0.50, 0.03 and 0.02. Thus the baseflow in any month is given by : P$_1$(n) =0.45 P(n) +0.50 P(n-I ) +0.03 P(n-$_2$) +0.02 P(n-$_3$) 5. The RDR model test gave estimated flows within +3.4 % and -1.0 % of the observed flows. 6. In the case of 3 consecutive no rain months, it was verified that 2.8 % of the dependable annual flow will be carried over the following year and 5.8 % of the potential annual baseflow will be transfered to the next year as a result of the rainfall-delayed response. The results of evaluating the pefformance of the RDR Model was generally satisfactory.

• The Korean Journal of Physiology
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• v.6 no.2
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• pp.39-48
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• 1972

Two polyethylene tubes were inserted into the esophagus of anesthetized rabbit in order to record the fluctuation of the intraluminal pressure through the orifices located near the tips of the tubes. The orifice of the first tube was 10 cm apart from the incisor of the rabbit and the orifice of the second tube was 5 cm below that of the first one. The tubes were filled with saline solution running at various rates ranging from 1.5 ml/min. to 4.2 ml/min. The tubes were connected to the pressure transducers and the electrical signals were recorded by the physiograph. When the peristaltic wave approached to the orifice a rise in the pressure was recorded, returning to the base line when the portion of the orifice was quiescent. The frequency of the peristaltic motion and the velocity of the wave were studied in connection with the flow rate of saline solution through the tubes and in the case of massive acute hemorrhage. The results obtained were as follows: 1. There was reflux of fluid induced during the procedure of the experiment. This outwrad flow through the pharynx seemed to elicite swallowing reflexes. Accordingly, the frequency of peristalsis of the esophagus was largely dependent on the flow rate of the fluid through the inserted tubes. By the flow rate of 1.5 ml/min., 2.5 ml/min., or 4.2 ml/min., the frequencies of the peristalsis were revealed to be $8.6{\pm}3.6/10min.,\;14.5{\pm}4.8/10min.\;or\;21.1{\pm}6.3/10min.,$ respectively. The velocity of peristalsis also coincided with the enhanced motility of the esophagus, showing $6.6{\pm}1.5\;cm/sec.,\;8.9{\pm}3.9\;cm/sec.,\;or\;12.4{\pm}4.6\;cm/sec.,$ respectively. 2. By acute hemorrhage, amounting to 2% of the body weight, the frequency of the peristalsis increased to twofold of the control and the propagation velocity also increased by 52 percent. 3. Retransfusion of the shed blood resulted in divergent responses. In some cases there were noticable ameliorations of the effects brought by acute hemorrhage, and in the others there were still increasing tendenies of the motility after the transfusion. 4. Some speculation was made about the possibility of a kind of relationship between the irreversibility of the hemorrhagic shock and the absence of responses by transfusion. 5. The peristalsis persisted even after complete disconnection at the midportion of the esophagus, reaffirming the view of a central regulation of the spatiotemporally coordinated motility, peristalsis.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.781-787
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• 2009

This report investigates the economic proprieties of commercial 50,000 barrel per day direct/indirect coal liquefaction(DCL/ICL) plants to produce commercial-grade diesel and naphtha liquids. The scope of the study includes capital and operating cost estimates, sensitivity analyses and a comparative financial analyses. Based on plant capacity of 50,000BPD, employing Illinois #6 bituminous coal as feed coal, the total capital cost appeared $3,994,858,000(DCL) and $4,962,263,000(ICL). Also, the internal rate of return of DCL/ICL appeared 13.27% and 12.68% on the base condition respectively. In this case, coal price and sale price of products were the most influence factors. And ICL's payback period(6.8 years) was longer than DCL's(6.6 years). According to sensitivity analyses, the important factors on both DCL/ICL processes were product sale price, feed coal price and the capital cost in order.

• The Korean Journal of Zoology
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• v.29 no.1
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• pp.23-30
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• 1986

Animals in Order Decapoda consist of a plentiful species and vary in external and internal shape, taste, feeding habit and the feature of alimentary canal. In this case, the morphological study on the midgut epithelium of filter feeding Decapoda in Crustacea, Korean fresh water crayfish (Cambaroides similis Koelbel), the only species dwelling in Korea, were performed by scanning electron microscopy. The anterior-most parts of midgut epithelium appeared to be many shallow, dense and irregular folds where a linear microvilli (MV) (1-3$\\mu$m long) numbered from a few to ten had raised. Middle part of the gut, the folds got gradually shallower. MV arranging on one, two or three lines were slightly thicker than those mentioned above. The number of MV in each group seemed gradual decrease from a apical border with maximum thirty in group to furrow with none. From the middle to posterior parts of the gut, the MV were slightly thinner and longer (2.5-4 $\\mu$m long) and raised twelve on a line and, in some cases, added from one to five on another line. On the posterior-end parts of the gut, the epithelium showed many shallow and dense folds as the anterior parts again. A group of thin and long MV (2-7 $\\mu$m long) countable fifteen on a line were raised to the base of each fold. In some cases, the MV also added utmost in five on the other line. All the MV observed in this study were posteriorly directed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.2
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• pp.174-190
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• 1996

Damage assessment based on in situ surveys for oil spills in marine environment is limited by fundamental difficulties as well as tremendous expenses. Except for intertidal zones, the damage is not preserved well. Also such surveys are usually confined to adult organisms. To overcome these limitations a computer model, NRDAM/CME, was developed in the case of USA (Reed et al., 1989), where an acute toxicity data base was used to assess indirect damages through food webs and loss due to recruitment as well as adult losses. In the present study damage assessment of natural biological resources for hypothetical oil spills is attempted using a computer model for hypothetical spills of Bunker C and heavy crude oil. In the model, the logical structure of NRDAM/CME was adopted, and biomass and productivity database were compiled for the Korean waters. The results showed that the damage increased in a nonlinear fashion as the spill amount increased. The magnitude of the damage depended upon the chemical properties of oil viscosity and solubility in particular, which implies that usage of oil dispersant might increase the damage by dispersing oil. The results also indicate that long term damage due to recruitment loss could be greater than short term damage.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.397-405
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• 2017

In case of inundation in a city where populations and properties are highly concentrated, unlike rural areas it is necessary to apply the method of calculating the damage amount considering the sewage overflow and the corresponding building damage. In this study, Dorim 1 drainage sector has been analyzed with Multi-Dimensional Flood Damage Assessment (MD-FDA) for flood forecast. It is analyzed with past flood history through the SWMM model and calculated the amount of damage with district base data and the result of flow analysis. The result of the SWMM model to predict a range of flood, it was shown that the wide area after 4 hours (at 16:30) by sewer overflow. The building damage was estimated using MD-FDA. As a result, the maximum flood area has shown as $205,955m^2$ (0~0.5 m: $205,190m^2$, over 0.5 m: $865m^2$) and estimated building damage of Dorim 1 drainage sector is approximately 15.5 billion KRW (Korean won) and other contents is 7 billion KRW (Korean won). Also from 0 to 0.5 m depth estimated damage is approximately 22.4 billion KRW (Korean won) and over 0.5 m is 100 million KRW (Korean won). Based on the results of this study, it would be necessary to estimate the amount of sub-divided flood damage in urban areas according to various damage patterns such as flood depth and flood time.