• Title/Summary/Keyword: high-flowing

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Crystal Structure of Dehydrated Partially Cobalt(II)-Exchanged Zeolite X, $Co_{41}Na_{10}-X$ (부분적으로 $Co^{2+}$ 이온으로 치환된 제올라이트 X, $Co_{41}Na_{10}-X$를 탈수한 결정구조)

  • Jang, Se-Bok;Jeong, Mi-Suk;Han, Young-Wook;Kim, Yang
    • Korean Journal of Crystallography
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    • v.6 no.2
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    • pp.125-133
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    • 1995
  • The crystal structure of dehydrated, partially Co(II)-exchanged zeolite X, stoichiometry Co2+Na+-X (Co41+Na10Si100Al92O384) per unit cell, has been determined from three-dimensional X-ray diffraction data gathered by counter methods. The structure was solved and refined in the cubic space group Fd3:α=24.544(1)Å at 21(1)℃. The crystal was prepared by ion exchange in a flowing stream using a solution 0.025 M each in Co(NO3)2 and Co(O2CCH3)2. The crystal was then dehydrated at 380℃ and 2×10-6 Torr for two days. The structure was refined to the final error indices, R1=0.059 and R2=0.046 with 211 reflections for which I > 3σ(I). Co2+ ions and Na+ ions are located at the four different crystallographic sites. Co2+ ions are located at two different sites of high occupancies. Sixteen Co2+ ions are located at the center of the double six-ring (site I; Co-O = 2.21(1)Å, O-Co-O = 90.0(4)°) and twenty-five Co2+ ions are located at site II in the supercage. Twenty-five Co2+ ions are recessed 0.09Å into the supercage from its three oxygen plane (Co-O = 2.05(1)Å, O-Co-O = 119.8(7)°). Na+ ions are located at two different sites of occupandies. Seven Na+ ions are located at site II in the supercage (Na-O = 2.29(1)Å, O-Na-O = 102(1)°). Three Na+ ions are statistically distribyted over site III, a 48-fold equipoint in the supercages on twofold axes (Na-O = 2.59(10)Å, O-Na-O = 69.0(3)°). Seven Na+ ions are recessed 1.02Å into the supercage from the three oxygen plane. It appears that Co2+ ions prefer sites I and II in order, and that Na+ ions occupy the remaining sites, II and III.

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The Behavior of Dissolved and Particulate Phases of Trace Elements within the Watershed of Juam Reservoir (주암호 집수유역 내 용존 및 입자상 미량원소의 거동 특성)

  • Lee, Pyeong-Koo;Chi, Se-Jung;Youm, Seung-Jun
    • Economic and Environmental Geology
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    • v.41 no.4
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    • pp.405-425
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    • 2008
  • In order to investigate the amounts of trace elements flowing into reservoir, and to elucidate the relationship between trace element mobility and fraction size, the stream water and sediment samples were collected from thirty-two sites of the 3rd or 4th order stream within watershed surrounding the Juam reservoir. Chemical analyses of trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) for all samples were completed, and additionally cationi and anion for stream water samples. Considering the distribution of rocks and contamination sources in watershed, the eight stream sediments were selected from typical sites representing study areas, and we determined the concentrations of trace elements according to size fractions ($2\;mm{\sim}200\;{\mu}m$, $200{\sim}100\;{\mu}m$, $100{\sim}50\;{\mu}m$, $50{\sim}20\;{\mu}m$ and < $20\;{\mu}m$). The correlation relationships between concentrations and size fractions of stream sediments were important to identify the hydro-geochemical behavior of trace elements that flow into Juam reservoir. Stream waters showed four water types (Ca-Mg-$HCO_3$, Ca-Na-$HCO_3$-Cl, Ca-Na-$HCO_3-SO_4$, Ca-Na-$HCO_3$) depending on pollution sources such as coal mine, metal mine, farm-land and dwellings. Concentrations of trace elements increased clearly with the decrease in size fractions of stream sediments. Concentrations of Cu, Pb and Zn increased dramatically in silt size (< $20\;{\mu}m$) fraction, while As had high concentrations in sand size ($2\;mm{\sim}100\;{\mu}m$) fraction in downstream sediments of metal mines. These indicate that Cu, Zn, and Pb moved into Juam reservoir easily in the adsorbed form on silt size grain in sediments, and As was transported as As-bearing mineral facies, resulting in its less chance to reach into Juam reservoir.

A Study on the Blood-Letting Therapy in Elementary Questions (("황제내경소문(黃帝內經素問)" 중(中) 사혈(瀉血)에 관한 연구(硏究))

  • Lee, Jun-Geun
    • Journal of the Korean Institute of Oriental Medical Informatics
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    • v.14 no.1
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    • pp.19-42
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    • 2008
  • Blood-Letting Therapy is a rational and ecological medical treatment by which we can heal most of the diseases by removing the static blood which precipitates in the blood vessel and blocks the flowing of blood. And the static blood is the generic term for the injurious, bad, dead and precipitated blood which is blocked the capillary vessel. The Yellow Emperor's Canon of Internal Medicine says that "the patient is treated with drugs internally and stone acupuncture externally. "In the old texts, the blood-letting therapy is mentioned as blood-letting, network vessel pricking, bloodletting, pricking, and arousing pulses etc and it is noted down as the method of network vessel pricking in 'On the Application of Needles' of Spiritual Pivot. Nine-pricking therapy, twelve-pricking therapy and five-pricking therapy are recorded in the methods of network vessel pricking and among them, the method of squeezing blood after pricking the affected part is explained as the network vessel pricking. There are four methods of network vessel pricking, pricking, picking, cluster needling and scatter-pricking and they are fluidly applied to the various symptoms of diseases. In 'On Discriminative Treating for Patients of Different Regions' in Elementary Questions, Ki-baek emphasizes "most of the local people, there are black in skin and loose in striate, and their diseases are mostly of carbuncle kind. It is suitable to treat the disease with stone therapy to prick with stone, so the stone therapy is transmitted from the east. "And in 'On the Corresponding Relation Between the Eum and Yang of Man and All Things' in Elementary Questions, when the Emperor asked Ki-Back, he answered "sthenia means the sthenia of evil, and deficiency means the deficiency of healthy energy. When the blood is sthenic, the evil should be discharged by pricking when out letting the blood; deficiency of vital energy is the asthenia of channels and network vessels, so the energy should drain from the channel which is not deficient, to replenish. "And in this case we can use the methods of 'Breaking out the static bloods', 'driving out the static bloods', blood-letting'. With this we can infer that the blood-letting therapy is made use of the important medical treatments from the ancient times. Especially in referring to the principles of treatment in The Yellow Emperor's Canon of Internal Medicine, it mostly alluded to acupuncture therapies and only eleven times to medicinal treatments. This is to verify that the blood-letting therapy formed the foundation of the medical art. In Dong's Therapy of Acupuncture-Moxibustion and Bloodletting, Dong Kyeong-Chang gave emphasis on the points that there must be extravasated bloods without exception in the serious illnesses which is old, unnatural, accompanying acute pains and so we can revive our body‘s sprit by circulating 'gi' and static blood piled up in the network vessel, regulating the weakness and strength, and controling the disharmony of the internal organs. The blood-letting therapy has effect on the orifice in emergency, such as fore draining, freeing network vessels, harmonizing gi and blood, relieving pain, dispersing swelling and concretion, sedation, resolving toxin as well as strengthening the heart, relieving itching. So it has distinguished effect on all kinds of medical treatment to the modern people. But by the change of social customs and the confucianism of confucius - it is widely spread on the period of North and South Dynasties, 'Wi' and 'Jin' in china and the period of the Three States in korea - The blood-letting therapy which was regarded as the most important medicinal treatment withered rapidly. And Confucius accentuated the importance of our body and all its members, loyalty and filial piety and banned any damage of our body under no circumstances. As a result of it, the therapy of blood-letting had a rapid decrease and barely kept itself in existence in both countries. What is worse, at the period of Japanese colonial rule of korea and our nation's founding of early stage, it has been withered by the high-handed policy to change Oriental Medicine into modern medical science. So the therapy of blood-letting barely kept itself in existence in some Buddhist temples. Another case, it has handed down as a old-fashioned quick fix in folk remedies. But all kinds of the contamination of heavy metals and the misuses of antibiotics are widely spread nowadays, which increased diseases of adult people and incurable diseases as modern society unavoidably made its way into a highly industrial society. To make us more miserable, the western medical science - the antibiotics and surgical operation medical science - already reveals itself into a limit. The necessity of a new medical science which can give a security to the patients who are suffering from the diseases of adult people and the incurable diseases is especially come into the force nowadays. In view of the results after bibliographically studying on the blood-letting Therapy in Elementary Questions of the Yellow Emperor's Canon of Internal Medicine, the blood-letting therapy has acted for the important Oriental medicinal science and has been clarified the prominent effects on the diseases of adult people and the incurable diseases. So it is regarded as an appropriate thing that we lay out a determined theory of the blood-letting therapy and of course prevent the unwanted side effects from inappropriate medicinal treatments, and make full use of clinic by elevating the curative value and that we win back our self-respect of medical treatment which is dominated from the western medical science and ultimately contribute to national medical welfare.

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A Study on the Divinity Construction of Temples in Sapa Region, Vietnam : Case of Den Hang Pho (베트남 사파(Sapa)지역 신전(神殿)의 신격(神格) 구성 고찰 - 덴항포(Den Hang Pho, SAPA)를 소재삼아 -)

  • Lee, Yoon Sun;LE, THI NGOC CAM
    • Journal of Korean Historical Folklife
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    • no.34
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    • pp.253-281
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    • 2010
  • This study has its purpose on figuring it out to the religious notion in Vietnam with the material of the divinity construction of Den Hang Pho in Sapa where is the northern region of Vietnam. To make this, the study divides the type of Vietnamese temples into four parts; Chua, Den, Dinh, and Mieu. Among them, the study pays attention to 'Den' because Vietnamese historical heroes are seated as divinity. This reason makes a reasonable case to this study to figure out a typically and generally religious faith. First of all, the study analyzes immaculate divinity, which generally consists of three and four layered system. The study confirms that the immaculate divinity started from the goddess and then extended to the concept to dominate the sky, the ground, the sea(river), and the mountain(forest). General Tran Hung Dao is the best historical hero in Vietnam and has been placed in temples called Den. The study exams the context that the divinity extended to the religious beliefs, for examples, the belief related in a childbirth by lots of narrations and ceremonies and the belief to treat a sickness, and also exams the context that the divinity placed in a divinity to make a symmetrical relation with immaculate faith. The study exams the divinity construction of Den Hang Pho as its authentic case. In this case, the study could verify a case emphasized by mountain Holy Mother among immaculate faiths. Especially, the study can confirm that General Tran Hung Dao was apotheosized as a concept to be symmetrized with immaculate divinity, and futhermore, a couple of snakes was emphasized by their positioning to every room. Tri-system lays stress on the aboriginality(locality) centered on minority races in the northern Vietnam, the national identity of Vietnam, and the ecological condition of rivers flowing the valley of high and steep peak. The confirmed facts could be said to a construction what the religious notion of tri-system makes. The study makes a conclusion that this kind of conversion-oriented religious notion naturally corresponded with region, nation, and ecologically environmental condition, and extended to the Vietnamese faith with polytheistic divinity.

Evaluation of microplastic in the inflow of municipal wastewater treatment plant according to pretreatment methods (전처리 방법에 따른 하수처리장 유입수에서의 미세플라스틱 성상분석 평가)

  • Kim, Sungryul;Gil, Kyungik
    • Journal of Wetlands Research
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    • v.24 no.2
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    • pp.83-92
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    • 2022
  • The amount of the plastic waste has been increasing according to global demand for plastic. Microplastics are the most hazardous among all plastic pollutants due to their toxicity and unknown physicochemical properties. This study investigates the optimal methodology that can be applied to sewage samples for detecting microplastics before discussing reducing microplastics in MWTPs. In this study, the effect of different pretreatment methods while detecting microplastic analysis of MWTP influent samples was investigated; the samples were collected from the J sewage treatment plant. There are many pretreatment methods but two of them are widely used: Fenton digestion and hydrogen peroxide oxidation. Although there are many pretreatment methods that can be applied to investigate microplastics, the most widely used methods for sewage treatment plant samples are Fenton digestion and H2O2 oxidation. For each pretreatment method, there were factors that could cause an error in the measurement. To overcome this, in the case of the Fenton digestion pretreatment, it is recommended to proceed with the analysis by filtration instead of the density separation method. In the case of the H2O2 oxidation method, the process of washing with distilled water after the reaction is recommended. As a result of the analysis, the concentration of microplastics was measured to be 2.75ea/L for the sample using the H2O2 oxidation method and 3.2ea/L for the sample using the Fenton oxidation method, and most of them were present in the form of fibers. In addition, it is difficult to guarantee the reliability of measurement results from quantitative analysis performed via microscope with eyes. A calibration curve was created for prove the reliability. A total of three calibration curves were drawn, and as a result of analysis of the calibration curves, all R2 values were more than 0.9. This ensures high reliability for quantitative analysis. The qualitative analysis could determine the series of microplastics flowing into the MWTP, but could not confirm the chemical composition of each microplastic. This study can be used to confirm the chemical composition of microplastics introduced into MWTP in the future research.

A Study on the Fengshui Shapes of the Four Propitious Sites Recorded in The Canonical Scripture (『전경』에 기록된 사명당(四明堂)의 풍수 물형(物形) 연구)

  • Shin Young-dae
    • Journal of the Daesoon Academy of Sciences
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    • v.41
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    • pp.133-178
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    • 2022
  • This study investigates if four propitious sites (四明堂, sa myeongdang) identified in Daesoon Jinrihoe's The Canonical Scripture correspond with the orthodox descriptions of dragon, energy hub, sand, and water (龍穴砂水, yong hyeol sa su) which are held by Fengshui as conditions necessary for that specific designation. In this study, these conditions, based on the shape of the site-formations, were observed via through on-site surveys and the application of the theories presented by traditional books on Fengshui. First, the dragon veins (龍脈, yongmaek) of the energy hub of the Five Immortals Playing Baduk (五仙圍碁穴 oseonwigi- hyeol) on Mount Hoemun in Sunchang consists of solid soil, is like a spiderweb, rises and lays prone, winds in every direction, and looks almost disconnected while actually remaining connected. Second, the Fengshui characteristics of the energy hub of Worship Held by Buddhist Monks from Abroad (胡僧禮佛穴, hoseungyebul- hyeol) on Mount Seungdal in Muan is that the branching feet (枝脚 jigak) support the mountain range by forming a valley to the left and right of the dragon veins that stretch from the peak of Mount Seungdal. Also, the direction-changing helm (橈棹 yodo) supports the mountain range solidly can be said to be well-developed. It is likewise noted that there is an excellent change in dragon veins in that exhibit curvature that spans being high, low, rising, and lying. This makes it appear as though the dragon is wriggling back and forth. Third, the state of the energy hub of Celestial Maidens Weaving Silk (仙女織錦穴, seonnyojikgeum-hyeol) on Sonryong Ridge in Jangseong County demonstrates overall harmony between mountain and water as it is near Mount Ju and Mount An and has a solid water outlet to which it is tightly fastened such that its energy does not leak out. Meanwhile, the positioning of its blue dragon of the east, red phoenix of the south, white tiger of the west, and black tortoise of the north is so intimate that its long flow can be said to be spinning. The Songryong Ridge area where energy hub was formed between soil and bedrock is the right land for a great favored location as it corresponds with Fengshui logic in an exemplary manner. Fourth, the Fengshui characteristics of the energy hub of Subjects Receiving the Imperial Command (群臣奉詔穴, gunshinbongjo-hyeol) at Baerye-jeon Field in Taein can be described as embracing the village snuggly as it centers around Mount Wangja, and its blue dragon and white tiger respond to each other. Additionally, a clear distinction between host and guest is noticeable in the positions of Mount Ju and Mount An. The flowing body of water in front of the village wraps around that village as a Horizontal Water Formation (橫水局, hoengsuguk), and vigorous vapor from the earth draws breath as the yin-yang energy of the landscape courses through the earth. As dragon veins, the range of the mountain, are like the blood vessels within the human body and the dragon is compared to the limbs, the energy hub of Subjects Receiving the Imperial Command at Baerye-jeon Field in Taein can be identified as a favored location that was formed directly by the sky and earth.

Influence of a chemical additive on the reduction of highly concentrated ammonium nitrogen(NH4+-N) in pig wastewater (양돈 폐수로부터 고농도 암모니아성 질소의 감소를 위한 화학적 첨가제의 영향)

  • Su Ho Bae;Eun Kim;Keon Sang Ryoo
    • Korean Journal of Environmental Biology
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    • v.40 no.3
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    • pp.267-274
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    • 2022
  • Excess nitrogen (N) flowing from livestock manure to water systems poses a serious threat to the natural environment. Thus, livestock wastewater management has recently drawn attention to this related field. This study first attempted to obtain the optimal conditions for the further volatilization of NH3 gas generated from pig wastewater by adjusting the amount of injected magnesia (MgO). At 0.8 wt.% of MgO (by pig wastewater weight), the volatility rate of NH3 increased to 75.5% after a day of aeration compared to untreated samples (pig wastewater itself). This phenomenon was attributed to increases in the pH of pig wastewater as MgO dissolved in it, increasing the volatilization efficiency of NH3. The initial pH of pig wastewater was 8.4, and the pH was 9.2 when MgO was added up to 0.8 wt.%. Second, the residual ammonia nitrogen (NH4+-N) in pig wastewater was removed by precipitation in the form of struvite (NH4MgPO4·6H2O) by adjusting the pH after adding MgO and H3PO4. Struvite produced in the pig wastewater was identified by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analysis. White precipitates began to form at pH 6, and the higher the pH, the lower the concentration of NH4+-N in pig wastewater. Of the total 86.1% of NH4+-N removed, 62.4% was achieved at pH 6, which was the highest removal rate. Furthermore, how struvite changes with pH was investigated. Under conditions of pH 11 or higher, the synthesized struvite was completely decomposed. The yield of struvite in the precipitate was determined to be between 68% and 84% through a variety of analyses.

Habitat characteristics and prediction of potential distribution according to climate change for Macromia daimoji Okumura, 1949 (Odonata: Macromiidae) (노란잔산잠자리(Macromia daimojiOkumura, 1949)의 서식지 특성 및 기후변화에 따른 잠재적 분포 예측)

  • Soon Jik Kwon;Hyeok Yeong Kwon;In Chul Hwang;Chang Su Lee;Tae Geun Kim;Jae Heung Park;Yung Chul Jun
    • Journal of Wetlands Research
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    • v.26 no.1
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    • pp.21-31
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    • 2024
  • Macromia daimoji Okumura, 1949 was designated as an endangered species and also categorized as Class II Endangered wildlife on the International Union for Conservation of Nature (IUCN) Red List in Korea. The spatial distribution of this species ranged within a region delimited by northern latitude from Sacheon-si(35.1°) to Yeoncheon-gun(38.0°) and eastern longitude from Yeoncheon-gun(126.8°) to Yangsan-si(128.9°). They generally prefer microhabitats such as slowly flowing littoral zones of streams, alluvial stream islands and temporarily formed puddles in the sand-based lowland streams. The objectives of this study were to analyze the similarity of benthic macroinvertebrate communities in M. daimoji habitats, to predict the current potential distribution patterns as well as the changes of distribution ranges under global climate change circumstances. Data was collected both from the Global Biodiversity Information Facility (GBIF) and by field surveys from April 2009 to September 2022. We adopted MaxEnt model to predict the current and future potential distribution for M. daimoji using downloaded 19 variables from the WorldClim database. The differences of benthic macroinvertebrate assemblages in the mainstream of Nakdonggang were smaller than those in its tributaries and the other streams, based on the surrounding environments and stream sizes. MaxEnt model presented that potential distribution displayed high inhabiting probability in Nakdonggang and its tributaries. Applying to the future scenarios by Intergovernmental Panel on Climate Change (IPCC), SSP1 scenario was predicted to expand in a wide area and SSP5 scenario in a narrow area, comparing with current potential distribution. M. daimoji is not only directly threatened by physical disturbances (e.g. river development activities) but also vulnerable to rapidly changing climate circumstances. Therefore, it is necessary to monitor the habitat environments and establish conservation strategies for preserving population of M. daimoji.

Calculation of Unit Hydrograph from Discharge Curve, Determination of Sluice Dimension and Tidal Computation for Determination of the Closure curve (단위유량도와 비수갑문 단면 및 방조제 축조곡선 결정을 위한 조속계산)

  • 최귀열
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.7 no.1
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    • pp.861-876
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    • 1965
  • During my stay in the Netherlands, I have studied the following, primarily in relation to the Mokpo Yong-san project which had been studied by the NEDECO for a feasibility report. 1. Unit hydrograph at Naju There are many ways to make unit hydrograph, but I want explain here to make unit hydrograph from the- actual run of curve at Naju. A discharge curve made from one rain storm depends on rainfall intensity per houre After finriing hydrograph every two hours, we will get two-hour unit hydrograph to devide each ordinate of the two-hour hydrograph by the rainfall intensity. I have used one storm from June 24 to June 26, 1963, recording a rainfall intensity of average 9. 4 mm per hour for 12 hours. If several rain gage stations had already been established in the catchment area. above Naju prior to this storm, I could have gathered accurate data on rainfall intensity throughout the catchment area. As it was, I used I the automatic rain gage record of the Mokpo I moteorological station to determine the rainfall lntensity. In order. to develop the unit ~Ydrograph at Naju, I subtracted the basic flow from the total runoff flow. I also tried to keed the difference between the calculated discharge amount and the measured discharge less than 1O~ The discharge period. of an unit graph depends on the length of the catchment area. 2. Determination of sluice dimension Acoording to principles of design presently used in our country, a one-day storm with a frequency of 20 years must be discharged in 8 hours. These design criteria are not adequate, and several dams have washed out in the past years. The design of the spillway and sluice dimensions must be based on the maximun peak discharge flowing into the reservoir to avoid crop and structure damages. The total flow into the reservoir is the summation of flow described by the Mokpo hydrograph, the basic flow from all the catchment areas and the rainfall on the reservoir area. To calculate the amount of water discharged through the sluiceCper half hour), the average head during that interval must be known. This can be calculated from the known water level outside the sluiceCdetermined by the tide) and from an estimated water level inside the reservoir at the end of each time interval. The total amount of water discharged through the sluice can be calculated from this average head, the time interval and the cross-sectional area of' the sluice. From the inflow into the .reservoir and the outflow through the sluice gates I calculated the change in the volume of water stored in the reservoir at half-hour intervals. From the stored volume of water and the known storage capacity of the reservoir, I was able to calculate the water level in the reservoir. The Calculated water level in the reservoir must be the same as the estimated water level. Mean stand tide will be adequate to use for determining the sluice dimension because spring tide is worse case and neap tide is best condition for the I result of the calculatio 3. Tidal computation for determination of the closure curve. During the construction of a dam, whether by building up of a succession of horizontael layers or by building in from both sides, the velocity of the water flowinii through the closing gapwill increase, because of the gradual decrease in the cross sectional area of the gap. 1 calculated the . velocities in the closing gap during flood and ebb for the first mentioned method of construction until the cross-sectional area has been reduced to about 25% of the original area, the change in tidal movement within the reservoir being negligible. Up to that point, the increase of the velocity is more or less hyperbolic. During the closing of the last 25 % of the gap, less water can flow out of the reservoir. This causes a rise of the mean water level of the reservoir. The difference in hydraulic head is then no longer negligible and must be taken into account. When, during the course of construction. the submerged weir become a free weir the critical flow occurs. The critical flow is that point, during either ebb or flood, at which the velocity reaches a maximum. When the dam is raised further. the velocity decreases because of the decrease\ulcorner in the height of the water above the weir. The calculation of the currents and velocities for a stage in the closure of the final gap is done in the following manner; Using an average tide with a neglible daily quantity, I estimated the water level on the pustream side of. the dam (inner water level). I determined the current through the gap for each hour by multiplying the storage area by the increment of the rise in water level. The velocity at a given moment can be determined from the calcalated current in m3/sec, and the cross-sectional area at that moment. At the same time from the difference between inner water level and tidal level (outer water level) the velocity can be calculated with the formula $h= \frac{V^2}{2g}$ and must be equal to the velocity detertnined from the current. If there is a difference in velocity, a new estimate of the inner water level must be made and entire procedure should be repeated. When the higher water level is equal to or more than 2/3 times the difference between the lower water level and the crest of the dam, we speak of a "free weir." The flow over the weir is then dependent upon the higher water level and not on the difference between high and low water levels. When the weir is "submerged", that is, the higher water level is less than 2/3 times the difference between the lower water and the crest of the dam, the difference between the high and low levels being decisive. The free weir normally occurs first during ebb, and is due to. the fact that mean level in the estuary is higher than the mean level of . the tide in building dams with barges the maximum velocity in the closing gap may not be more than 3m/sec. As the maximum velocities are higher than this limit we must use other construction methods in closing the gap. This can be done by dump-cars from each side or by using a cable way.e or by using a cable way.

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