• Title/Summary/Keyword: cold region

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Distributions of Dissolved Pb and Cd in the Surface Water of East Sea, Korea (동해 표층수중 용존 Pb, Cd의 분포 특성)

  • Yoon, Sang Chol;Yoon, Yi Yong
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.18 no.2
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    • pp.64-73
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    • 2015
  • The distributions of Pb and Cd concentrations in the surface seawater of the East Sea were investigated during the R/V Lavrentyev cruise (July 2009) in which four transects from Russia shore to South were conducted to collect 26 surface water samples. The total dissolved concentrations of Pb and Cd were measured using ICP-MS (Perkin Elmer, DRC-e). In the coastal area, their concentrations of Russia shore (Pb, 0.08; Cd, 0.10 nM) were comparable for Cd but on the other hand, 6 times lower for Pb than Korea shore (Pb, 0.49; Cd, 0.11 nM). In the subregion, their concentrations of Warm region (Pb, 0.22; Cd, 0.01 nM) were about 1.7 times higher for Pb but 0.4 lower for Cd than Cold region (Pb, 0.13; Cd, 0.14 nM). The distributions of Pb and Cd concentrations were divided by lowest level at $10^{\circ}C$ of water temperature. Below $10^{\circ}C$, Pb and Cd concentrations increased when surface water temperatures decreased. Above $10^{\circ}C$, their concentrations increased with temperature, which showed highest concentrations in the Ulleung basin, directly influenced by flux from East Korean Warm Current and neighboring countrys (Korea and Japan). Specially, in the case of Pb, the concentrations decrease remarkablely with temperatures decrease from D10 directly influenced by flux from East Korean Warm Current, which shows highest Pb level. By comparing with other sea areas (Western Mediterranean, East Pacific), Pb concentrations in the East Sea were a little higher. The influence of East Korean Warm Current and neighboring countrys (Korea and Japan) may be relatively important. Therefore, the distribution of Cd may primarily be influenced by mixing of different water masses while the distribution of Pb may mainly be influenced by flux from East Korean Warm Current and atmospheric inputs. River inputs and interaction with particulate materials may also some roles for the distribution of these elements.

Effect of Self-Perception of Health and Related Factors of Food Life and Disease on Health Foods Intakes among the Middle Aged in the Jeonbuk Region (전북 일부지역 중년의 건강 자가인식도와 식생활 및 질병 관련인자가 건강식품 섭취에 미치는 영향)

  • 장혜순;김미라
    • Korean Journal of Community Nutrition
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    • v.6 no.5
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    • pp.744-754
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    • 2001
  • This study examined the effect of self-perception of health and related factors of flood life and disease on health floods intakes among the middle aged(150 men and 159 women) in the Jeonbuk region. The health foods were classified into 4 groups including Chinese medicine(CM), toner foods(TF), nutritional supplements(NS), and other manufactured health foods supplements(MHFS). Differences of BMI and self-perception for body shape was that overweight was 30% in men and 24.5% in women on BMI, but conversely was 21.3% in men and 43.4% in women on self-perception for body shape. Men thought themselves more than normal weight, but women thought themselves less than normal weight for the criteria of normal weight. Consumption of CM was high in the overweight group on BMI and was a low in the overweight group on self-perception for bodyshape Men thought themselves better than women and those in their 40's thought better than those in their 50's on self perception of health status, and women were better than men on self-perception of food habits. The difference of health foods intakes according to the self-perception of health status and food habits was not significant. The points of food habits, food attitude and nutrition knowledge were 11.21 $\pm$ 2.43, 68.18 $\pm$ 15.56 and 15.53 $\pm$ 1.59 in women and 10.49 $\pm$ 2.71, 67.53 $\pm$ 14.41, and 15.11 $\pm$ 1.79 in men respectively. The points of all were higher for women than for men. Consumption of CM (p < 0.01) and TF(p < 0.01) were a low in groups that scored high points on nutrition knowledge. The points of climacteric symptoms were that men were 48.36 $\pm$ 6.30 and woman were 46.43 $\pm$ 6.70. Men thought themselves in good condition more than women(p < 0.01), and those in their 40's thought themselves in good condition as opposed to those in their 50's in men(p < 0.05). Consumption of TF and NS were high in the low points group on climacteric symptoms(p < 0.01). Women were higher than men on morbidity, but men were more than women on cases of liver disease(p < 0.01). Consumption of CM was high in the liver disease group(p < 0.05), MHFS was high in the kidney disease group(p < 0.05), TF and NS were hgih in the bone disease group(p < 0.05) and NS was hgih in the endocrine disease group(p < 0.05). People in their 40's were higher than those in their 50's in men on morbidity of cold(p < 0.05), women were higher than men by about 2 times on constipation (p < 0.01), those in their 40's were higher than those in their 50's in mein on gastritis(p < 0.05). Consumption of NS was highest for those with diseases in respiratory organs and gastrointestinal tracts. This study suggests that nutritional education for the right recognition of self-perception of health status and food habits, and nutrition knowledge are needed to select for health floods. Consumption of health foods was different according to kinds of diseases. Thus, recognition of etiology, symptoms and dietetics of diseases is needed to select adequate health foods for diseases in middle age.

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Total Spinal Block and Cortical Epidural Block for Whiplash Syndrome and Reflex Sympathetic Dystrophy (Report of Four Cases) (전척수(全脊髓) 및 경막외차단(硬膜外遮斷)으로 편타성(鞭打性) 손상(損傷)의 통증치험(痛症治驗) (4례(例) 보고(報告)))

  • Park, Wook;Ok, See-Young;Song, Hoo-Bin
    • The Korean Journal of Pain
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    • v.1 no.1
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    • pp.106-119
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    • 1988
  • For the relief of pain in 3 cases of whiplash syndromes (case I, II and IV) and in one of reflex sympathetic dystrophy (case III), we have carried out six intentional. total spinal blocks (TSB) which attempted two times in case I, three in case II and one in carte III whoso various symptoms were chronically unresponsive to the usual conservative treatments, and a time of cervical epidural and right suprascapular nerve block in case W whose acute symptom lasted 4 drys following the cervical injury (see fables from 1 to 9). During the 753, we have observed clinically the sequential charges of respiration, lid and pupil reflexes, body motion and consciousness. And checked the blood pressure, pulse rate and arterial Pco2. The effectiveness of those blocks has been assessed by using the Visual Analog Scale which is designed to measure the patient$\acute{s}$ subjective intensity of pain and also we have found out the sequelae following those blocks. The methods of the blocks were as the following: 1. Under the N.P.O. for 8~10 hours, the preparations of immediate cardiopulmonary resuscitation and premedication with atropine 0.5mg at thirty minutes before the TSB, it was performed by injecting the mixture of 2% mepivacaine 10 or 15ml and normal saline 10 or 5ml through No. 23 G. spinal needle into the subarachnoid space of $C_7-T_1$ interspinous region with fully flexed neck on the lateral posture. Immediately after the injection of the local anesthetic in the lateral position, the patient$\acute{s}$ were hasten to change Trendelenburg$\acute{s}$ position in order to act the drugs cephalad and to make easy controlled respiration with oxygen. 2. The cervical epidural block was done by injecting the mixture of 0.5% bupivacaine 4ml, normal saline 4ml and triamcinolone 15mg through No. 18 G. Tuohy needle into the epidural space on the same region and posture as the above without premedication.7he suprascapular nerve block was done by injecting of 0.5% bupivacaine 3ml only into the right suprascapular fossa on the sitting posture. The results were as the following: 1. The cessation of respiration was seen within 5 minutes following the subarachnoidal injection of the above 20ml mixture in 2 to 3 minutes and then soon the consciousness began to disappear. The loss of Lid and pupil reflexes noted between 5 to 10 minutes and the size of the dilated pupils was equal between 5 to 20 minutes, but the pupil of the dependent side on tile lateral position was dilated 1 to 3 minutes earlier than that of the independent. The patients had r=ever responded to any stimulations during the TSB except their heart funtion. 2. The recovery of the TSB was as the following, firstly the ankle and lower limb of the independent side began to move slightly with in 34 to 75 minutes after the injection and then that of the dependent Secondly the neck and upper limb moved 6 to 15 minutes later than the lower limb. Thirdly the self respiration began to appear between 40 to 80 minutes from the block. The lid and pupil reacted to touch and light respectively between 40 to 80 minutes but the pupil of the independent side responded earlier than that of the depends. Lastly the consciousness recovered completely between 80 to 125 minutes from the block. 3. In the cardiopulmonary function during the TSB, the blood pressure were stable except the 210/130 tory at the and block of case I. There were bradycardias between 65 to 85 minutes in case I and II but no arrythmia on the EKG. The level of the arterial Pco2 was maintained to 43~45 torr during the TSB. 4. The effectiveness of the above blocks was no pain(0%) in case IV, and light (10~20%) in case I and II but no improvement in case III. 5. The right arm weakness has been complicated as to be Injected accidently the "COLD" local anesthetic at the End block of case I.

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Study on sea fog detection near Korea peninsula by using GMS-5 Satellite Data (GMS-5 위성자료를 이용한 한반도 주변 해무탐지 연구)

  • 윤홍주
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.4
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    • pp.875-884
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    • 2000
  • Sea fog/stratus is very difficult to detect because of the characteristics of air-sea interaction and locality ,and the scantiness of the observed data from the oceans such as ships or ocean buoys. The aim of our study develops new algorism for sea fog detection by using Geostational Meteorological Satellite-5(GMS-5) and suggests the technics of its continuous detection. In this study, atmospheric synoptic patterns on sea fog day of May, 1999 are classified; cold air advection type(OOUTC, May 10, 1999) and warm air advection type(OOUTC, May 12, 1999), respectively, and we collected two case days in order to analyze variations of water vapor at Osan observation station during May 9-10, 1999.So as to detect daytime sea fog/stratus(OOUTC, May 10, 1999), composite image, visible accumulated histogram method and surface albedo method are used. The characteristic value during day showed A(min) .20% and DA < 10% when visible accumulated histogram method was applied. And the sea fog region which is detected is similar in composite image analysis and surface albedo method. Inland observation which visibility and relative humidity is beneath 1Km and 80%, respectively, at OOUTC, May 10,1999; Poryoung for visble accumulated histogram method and Poryoung, Mokp'o and Kangnung for surface albedo method. In case of nighttime sea fog(18UTC, May 10, 1999), IR accumulated histogram method and Maximum brightness temperature method are used, respectively. Maxium brightness temperature method dectected sea fog better than IR accumulated histogram method with the charateristic value that is T_max < T_max_trs, and then T_max is beneath 700hPa temperature of GDAPS(Global Data Assimilation and Prediction System). Sea fog region which is detected by Maxium brighness temperature method was similar to the result of National Oceanic and Atmosheric Administratio/Advanced Very High Resolution Radiometer (NOAA/AVHRR) DCD(Dual Channel Difference), but usually visibility and relative humidity are not agreed well in inland.

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A Review of Recent Climate Trends and Causes over the Korean Peninsula (한반도 기후변화의 추세와 원인 고찰)

  • An, Soon-Il;Ha, Kyung-Ja;Seo, Kyong-Hwan;Yeh, Sang-Wook;Min, Seung-Ki;Ho, Chang-Hoi
    • Journal of Climate Change Research
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    • v.2 no.4
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    • pp.237-251
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    • 2011
  • This study presents a review on the recent climate change over the Korean peninsula, which has experienced a significant change due to the human-induced global warming more strongly than other regions. The recent measurement of carbon dioxide concentrations over the Korean peninsula shows a faster rise than the global average, and the increasing trend in surface temperature over this region is much larger than the global mean trend. Recent observational studies reporting the weakened cold extremes and intensified warm extremes over the region support consistently the increase of mean temperature. Surface vegetation greenness in spring has also progressed relatively more quickly. Summer precipitation over the Korean peninsula has increased by about 15% since 1990 compared to the previous period. This was mainly due to an increase in August. On the other hand, a slight decrease in the precipitation (about 5%) during Changma period (rainy season of the East Asian summer monsoon), was observed. The heavy rainfall amounts exhibit an increasing trend particularly since the late 1970s, and a consecutive dry-day has also increased primarily over the southern area. This indicates that the duration of precipitation events has shortened, while their intensity became stronger. During the past decades, there have been more stronger typhoons affecting the Korean peninsula with landing more preferentially over the southeastern area. Meanwhile, the urbanization effect is likely to contribute to the rapid warming, explaining about 28% of total temperature increase during the past 55 years. The impact of El Nino on seasonal climate over the Korean peninsula has been well established - winter [summer] temperatures was generally higher [lower] than normal, and summer rainfall tends to increase during El-Nino years. It is suggested that more frequent occurrence of the 'central-Pacific El-Nino' during recent decades may have induced warmer summer and fall over the Korean peninsula. In short, detection and attribution studies provided fundamental information that needed to construct more reliable projections of future climate changes, and therefore more comprehensive researches are required for better understanding of past climate variations.

Analysis of the Causes of Subfrontal Recurrence in Medulloblastoma and Its Salvage Treatment (수모세포종의 방사선치료 후 전두엽하방 재발된 환자에서 원인 분석 및 구제 치료)

  • Cho Jae Ho;Koom Woong Sub;Lee Chang Geol;Kim Kyoung Ju;Shim Su Jung;Bak Jino;Jeong Kyoungkeun;Kim Tae_Gon;Kim Dong Seok;Choi oong-Uhn;Suh Chang Ok
    • Radiation Oncology Journal
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    • v.22 no.3
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    • pp.165-176
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    • 2004
  • Purpose: Firstly, to analyze facto in terms of radiation treatment that might potentially cause subfrontal relapse in two patients who had been treated by craniospinal irradiation (CSI) for medulloblastoma, Secondly, to explore an effective salvage treatment for these relapses. Materials and Methods: Two patients who had high-risk disease (T3bMl, T3bM3) were treated with combined chemoradiotherapy CT-simulation based radiation-treatment planning (RTP) was peformed. One patient who experienced relapse at 16 months after CSI was treated with salvage surgery followed by a 30.6 Gy IMRT (intensity modulated radiotherapy). The other patient whose tumor relapsed at 12 months after CSI was treated by surgery alone for the recurrence. To investigate factors that might potentially cause subfrontal relapse, we evaluated thoroughly the charts and treatment planning process including portal films, and tried to find out a method to give help for placing blocks appropriately between subfrotal-cribrifrom plate region and both eyes. To salvage subfrontal relapse in a patient, re-irradiation was planned after subtotal tumor removal. We have decided to treat this patient with IMRT because of the proximity of critical normal tissues and large burden of re-irradiation. With seven beam directions, the prescribed mean dose to PTV was 30.6 Gy (1.8 Gy fraction) and the doses to the optic nerves and eyes were limited to 25 Gy and 10 Gy, respectively. Results: Review of radiotherapy Portals clearly indicated that the subfrontal-cribriform plate region was excluded from the therapy beam by eye blocks in both cases, resulting in cold spot within the target volume, When the whole brain was rendered in 3-D after organ drawing in each slice, it was easier to judge appropriateness of the blocks in port film. IMRT planning showed excellent dose distributions (Mean doses to PTV, right and left optic nerves, right and left eyes: 31.1 Gy, 14.7 Gy, 13.9 Gy, 6.9 Gy, and 5.5 Gy, respectively. Maximum dose to PTV: 36 Gy). The patient who received IMRT is still alive with no evidence of recurrence and any neurologic complications for 1 year. Conclusion: To prevent recurrence of medulloblastoma in subfrontal-cribriform plate region, we need to pay close attention to the placement of eye blocks during the treatment. Once subfrontal recurrence has happened, IMRT may be a good choice for re-irradiation as a salvage treatment to maximize the differences of dose distributions between the normal tissues and target volume.

Study for the Deficiency and Excessiveness Diagnosis in the Front Point by Elastic State (모혈(募穴)의 탄력(彈力) 상태(狀態) 측정(測定)에 의한 허실(虛實) 진단(診斷) 연구(硏究))

  • Na, Chang-Su;Yoon, Yeo-Choong;Park, Hyun-Cheal;Lee, Dong-Kyu;Choi, Chan-Hern;Jang, Kyung-Sun;So, Cheal-Ho
    • Journal of Acupuncture Research
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    • v.17 no.1
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    • pp.27-41
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    • 2000
  • The meridian system is the most essential and basic connecting structure that maintains the vital activities of viscera and bowels by connecting them with each part of body's surface. Doctors can understand the healthy condition, and the region and deficiency-excessiveness of disease by observing the condition of Qi flowing. Deficiency and excessiveness could be differentiated by various symptoms expressed in meridian system. Especially there could be several clues like pain, heat-cold, protuberance-depression, change of color and shine in the line of channel leads to the judgment of deficiency-excessiveness The diagnosis of deficiency and excessiveness can be generalized by quantification of elastic status in skin surface along the meridian system. By comparing data from measurement of elastic condition with those from traditional deficiency and excessiveness, it could be utilized for the development of oriental medicine. All biological activities in the human body are based on meridian system according to the oriental medicine. Also the meridian system is viewed as basic and essential structure connecting internal viscera and each part of body. The areas of expressed channel phenomena are muscle to bone, muscle to muscle and bone to bone. These areas are called depression where meridian system is present and any changing state on those points can be measured. It could be difficult in diagnosing the reaction of meridian system because doctor can depend on his own judgment. Therefore, it is necessary to quantify and indexate channel reactions. To quantify the channel reactions, specially manufactured instrument was used to quantify the protuberance and depression to differentiate the deficiency and excessiveness. The results follow as below; 1. The elastic index measurement by the equipment proved a pattern of agreement showing the values that ranged within standard deviation 0.05kgf/cm throughout the experiment except few cases' measurement in CV-17. 2. To evaluate the state of deficiency & excessiveness of elastic index measurements in frontal point, elastic index measurements in the front paint were compared to the elastic index measured surrounding the point within 2.5 cm. Such result of indexing procedure was closely matched to the concept of palpitation. 3. If the elastic index values in the surrounding front point closely located to the elastic index values in the front point, the judgement on the state of deficiency and excessiveness was delayed. Otherwise, it was judged as deficiency or excessiveness. 4. Out of total 12 cases of comparing the elastic index values to the elastic index values in the surrounding front point, Three to nine front points were judged as either in the state of deficiency or excessiveness. 5. Among the nine front points judged as either in the state of deficiency or excessiveness, Four cases were matched to the electric index measured by EAV that evaluating the internal organs by five different phases. If more clinical cases are accumulated, it is expected to systematically theorize and improve the concept of deficiency and excessiveness in the internal organs using the front point.

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Treatment of Skin Diseases in Hyungsang Medicine (피부병의 형상의학적 치료)

  • Suk Min He;Hwang Won Duek;Jung Haeng Gyu;Lee Yong Tae
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.18 no.3
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    • pp.646-669
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    • 2004
  • By treating skin diseases with Hyungsang medicine and reviewing the clinical cases of them through classifying skin diseases into general care and into Hyungsang medical care, the writer came to the conclusion as followings. The skin is a house of Kyungnak, and it' s a place which Ki comes in and out, which human body controls conditions of his physiological function and which doctors can make a diagnosis from seeing it. The skin is subject to lung and large intestine in the point of organ, but in the point of movement, to spleen and stomach. Skin diseases come from unbalance of Ki and Hyul, mostly from fever in blood and also from Dam, Wind, Dampness and Dryness because of including fire. Generally skin diseases are treated according to classifying into distinctive symptoms, region, cause or time being occurred, and concomitant symptoms. After being divided into man and woman, age and youth, fatness and leanness, Jung Ki Shin Hyul type, visceral figures, Yukkyung shapes on Hyungsang medicine method, the remedy of skin diseases which is combined common meditation with Hyungsang medical method is efficacious. In distinguishing into man and woman, age and youth, man gets sick mainly by drinking liquor and exhausting Jung, woman is taken ill generally by indigestion and Damwha, especially by drinking liquor. Young child gets ill mostly from inherent weakness, but in many cases he is occurred by disturbed digestion, so he must be taken care of ingesting food. The aged becomes ill from weakening, so he must be treated according to reasons of diseases. To fatness and leanness, skin diseases are showed symptoms by weakened Yang, insufficient Yin or excess fever on the theory of upper and lower parts, by unbalance of Ki and Hyul on the theory of left and right, by Dryness and Dampness on the theory of front and rear and by insufficiency of vitality and combined fever on the theory of inside and outside. Therefore doctors must cure the symptoms according to the theory of upper and lower, left and right, front and rear and inside and outside. In type of Jung Ki Shin Hyul, the balances between Jung-Hyul and Shin-Ki are important points. Concretely Jung type comes to easily shortage of Jung or gathering abnormally Dampness and Dam, Ki type is easy to make a mass with Ki or to be deficient of Ki, Shin type comes to press seven emotions togather or to be insufficient of Yin and fever inside, and Hyul type is inclined to be deficient of Hyul and to become feverish or to be deficient of Ki. Therefore on the ground of the above reasons skin diseases come into existence. Inclusively in Jung-Hyul type , Ki must be moved on the base of full Jung-Hyul, so Wukmijiwhangtang or Samultang is prescribed basically. In Shin-Ki type , Jung-Hyul is saved on the base of moving Ki, so Hyangsosan or Yijintang is the proper prescription. Considering the visceral figures, doctors judge for diagnosis and remedy by putting together the elements, that is, great and small sizes of a set of features (eye, ear, mouth, nose), color and temper. The yukkyung types are classified according to many or few of Ki-Hyul, and then skin diseases appear by being inclined toward one side between Ki and hyul, or among the six atmospheric elements(wind, cold, heat, dampness, dryness, and fire). Especially because Yangmyung type is full of much Ki and Hyul, and also has much fever in stomach, he gets skin symptoms frequently. So his prescription is based on taking off fever in stomach, and also he must be careful about regimen certainly.

Geological Characteristics of Extra Heavy Oil Reservoirs in Venezuela (베네주엘라 초중질유 저류층 지질 특성)

  • Kim, Dae-Suk;Kwon, Yi-Kyun;Chang, Chan-Dong
    • Economic and Environmental Geology
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    • v.44 no.1
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    • pp.83-94
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    • 2011
  • Extra heavy oil reservoirs are distributed over the world but most of them is deposited in the northern part of the Orinoco River in Venezuela, in the area of 5,500 $km^2$, This region, which has been commonly called "the Orinoco Oil Belt", contains estimated 1.3 trillion barrels of original oil-in-place and 250 billion barrels of established reserves. The Venezuela extra heavy oil has an API gravity of less than 10 degree and in situ viscosity of 5,000 cP at reservoir condition. Although the presence of extra heavy oil in the Orinoco Oil Belt has been initially reported in the 1930's, the commercial development using in situ cold production started in the 1990's. The Orinoco heavy oil deposits are clustered into 4 development areas, Boyaco, Junin, Ayachoco, and Carabobo respectively, and they are subdivided into totally 31 production blocks. Nowadays, PDVSA (Petr$\'{o}$leos de Venzuela, S.A.) makes a development of each production block with the international oil companies from more than 20 countries forming a international joint-venture company. The Eastern Venezuela Basin, the Orinoco Oil Belt is included in, is one of the major oil-bearing sedimentary basins in Venezuela and is first formed as a passive margin basin by the Jurassic tectonic plate motion. The major source rock of heavy oil is the late Cretaceous calcareous shale in the central Eastern Venezuela Basin. Hydrocarbon materials migrated an average of 150 km up dip to the southern margin of the basin. During the migration, lighter fractions in the hydrocarbon were removed by biodegradation and the oil changed into heavy and/or extra heavy oil. Miocene Oficina Formation, the main extra heavy oil reservoir, is the unconsolidated sand and shale alternation formed in fluvial-estuarine environment and also has irregularly a large number of the Cenozoic faults induced by basin subsidence and tectonics. Because Oficina Formation has not only complex lithology distribution but also irregular geology structure, geological evolution and characteristics of the reservoirs have to be determined for economical production well design and effective oil recovery. This study introduces geological formation and evolution of the Venezuela extra heavy oil reservoirs and suggest their significant geological characteristics which are (1) thickness and geometry of reservoir pay sands, (2) continuity and thickness of mud beds, (3) geometry of faults, (4) depth and geothermal character of reservoir, (5) in-situ stress field of reservoir, and (6) chemical composition of extra heavy oil. Newly developed exploration techniques, such as 3-D seismic survey and LWD (logging while drilling), can be expected as powerful methods to recognize the geological reservoir characteristics in the Orinoco Oil Belt.

Development of a Ranging Inspection Technique in a Sodium-cooled Fast Reactor Using a Plate-type Ultrasonic Waveguide Sensor (판형 웨이브가이드 초음파 센서를 이용한 소듐냉각고속로 원격주사 검사기법 개발)

  • Kim, Hoe Woong;Kim, Sang Hwal;Han, Jae Won;Joo, Young Sang;Park, Chang Gyu;Kim, Jong Bum
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.1
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    • pp.48-57
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    • 2015
  • In a sodium-cooled fast reactor, which is a Generation-IV reactor, refueling is conducted by rotating, but not opening, the reactor head to prevent a reaction between the sodium, water and air. Therefore, an inspection technique that checks for the presence of any obstacles between the reactor core and the upper internal structure, which could disturb the rotation of the reactor head, is essential prior to the refueling of a sodium-cooled fast reactor. To this end, an ultrasound-based inspection technique should be employed because the opacity of the sodium prevents conventional optical inspection techniques from being applied to the monitoring of obstacles. In this study, a ranging inspection technique using a plate-type ultrasonic waveguide sensor was developed to monitor the presence of any obstacles between the reactor core and the upper internal structure in the opaque sodium. Because the waveguide sensor installs an ultrasonic transducer in a relatively cold region and transmits the ultrasonic waves into the hot radioactive liquid sodium through a long waveguide, it offers better reliability and is less susceptible to thermal or radiation damage. A 10 m horizontal beam waveguide sensor capable of radiating an ultrasonic wave horizontally was developed, and beam profile measurements and basic experiments were carried out to investigate the characteristics of the developed sensor. The beam width and propagation distance of the ultrasonic wave radiated from the sensor were assessed based on the experimental results. Finally, a feasibility test using cylindrical targets (corresponding to the shape of possible obstacles) was also conducted to evaluate the applicability of the developed ranging inspection technique to actual applications.