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Nondestructive Evaluation and Microfailure Mechanisms of Single Fibers/Brittle Cement Matrix Composites using Electro-Micromechanical Technique and Acoustic Emission (Electro-Micromechanical 시험법과 Acoustic Emission을 이용한 단섬유/시멘트 복합재료의 미세파괴 메커니즘과 비파괴적 평가)

  • 박종만;이상일;김진원;윤동진
    • Composites Research
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    • v.14 no.3
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    • pp.18-31
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    • 2001
  • Interfacial and microfailure properties of the modified steel, carbon and glass fibers/cement composites were investigated using electro-pullout test under tensile and compressive tests with acoustic emission (AE). The hand-sanded steel composite exhibited higher interfacial shear strength (IFSS) than the untreated and even neoalkoxy zirconate (Zr) treated steel fiber composites. This might be due to the enhanced mechanical interlocking, compared to possible hydrogen or covalent bonds. During curing process, the contact resistivity decreased rapidly at the initial stage and then showed a level-off. Comparing to the untreated case, the contact resistivity of either Zr-treated or hand-sanded steel fiber composites increased to the infinity at latter stage. The number of AE signals of hand-sanded steel fiber composite was much more than those of the untreated and Zr-treated cases due to many interlayer failure signals. AE waveforms for pullout and frictional signals of the hand-sanded composite are larger than those of the untreated case. For dual matrix composite (DMC), AE energy and waveform under compressive loading were much higher and larger than those under tensile loading, due to brittle but well-enduring ceramic nature against compressive stress. Vertical multicrack exhibits fur glass fiber composite under tensile test, whereas buckling failure appeared under compressive loading. Electro-micromechanical technique with AE can be used as an efficient nondestructive (NDT) method to evaluate the interfacial and microfailure mechanisms for conductive fibers/brittle and nontransparent cement composites.

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Review of Anti-Leukemia Effects from Medicinal Plants (항 백혈병작용에 관련된 천연물의 자료조사)

  • Pae Hyun Ock;Lim Chang Kyung;Jang Seon Il;Han Dong Min;An Won Gun;Yoon Yoo Sik;Chon Byung Hun;Kim Won Sin;Yun Young Gab
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.17 no.3
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    • pp.605-610
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    • 2003
  • According to the Leukemia and Lymphoma Society, leukemia is a malignant disease (cancer) that originates in a cell in the marrow. It is characterized by the uncontrolled growth of developing marrow cells. There are two major classifications of leukemia: myelogenous or lymphocytic, which can each be acute or chronic. The terms myelogenous or lymphocytic denote the cell type involved. Thus, four major types of leukemia are: acute or chronic myelogenous leukemia and acute or chronic lymphocytic leukemia. Leukemia, lymphoma and myeloma are considered to be related cancers because they involve the uncontrolled growth of cells with similar functions and origins. The diseases result from an acquired (not inherited) genetic injury to the DNA of a single cell, which becomes abnormal (malignant) and multiplies continuously. In the United States, about 2,000 children and 27,000 adults are diagnosed each year with leukemia. Treatment for cancer may include one or more of the following: chemotherapy, radiation therapy, biological therapy, surgery and bone marrow transplantation. The most effective treatment for leukemia is chemotherapy, which may involve one or a combination of anticancer drugs that destroy cancer cells. Specific types of leukemia are sometimes treated with radiation therapy or biological therapy. Common side effects of most chemotherapy drugs include hair loss, nausea and vomiting, decreased blood counts and infections. Each type of leukemia is sensitive to different combinations of chemotherapy. Medications and length of treatment vary from person to person. Treatment time is usually from one to two years. During this time, your care is managed on an outpatient basis at M. D. Anderson Cancer Center or through your local doctor. Once your protocol is determined, you will receive more specific information about the drug(s) that Will be used to treat your leukemia. There are many factors that will determine the course of treatment, including age, general health, the specific type of leukemia, and also whether there has been previous treatment. there is considerable interest among basic and clinical researchers in novel drugs with activity against leukemia. the vast history of experience of traditional oriental medicine with medicinal plants may facilitate the identification of novel anti leukemic compounds. In the present investigation, we studied 31 kinds of anti leukemic medicinal plants, which its pharmacological action was already reported through many experimental articles and oriental medical book: 『pharmacological action and application of anticancer traditional chinese medicine』 In summary: Used leukemia cellline are HL60, HL-60, Jurkat, Molt-4 of human, and P388, L-1210, L615, L-210, EL-4 of mouse. 31 kinds of anti leukemic medicinal plants are Panax ginseng C.A Mey; Polygonum cuspidatum Sieb. et Zucc; Daphne genkwa Sieb. et Zucc; Aloe ferox Mill; Phorboc diester; Tripterygium wilfordii Hook .f.; Lycoris radiata (L Her)Herb; Atractylodes macrocephala Koidz; Lilium brownii F.E. Brown Var; Paeonia suffruticosa Andr.; Angelica sinensis (Oliv.) Diels; Asparagus cochinensis (Lour. )Merr; Isatis tinctoria L.; Leonurus heterophyllus Sweet; Phytolacca acinosa Roxb.; Trichosanthes kirilowii Maxim; Dioscorea opposita Thumb; Schisandra chinensis (Rurcz. )Baill.; Auium Sativum L; Isatis tinctoria, L; Ligustisum Chvanxiong Hort; Glycyrrhiza uralensis Fisch; Euphorbia Kansui Liou; Polygala tenuifolia Willd; Evodia rutaecarpa (Juss.) Benth; Chelidonium majus L; Rumax madaeo Mak; Sophora Subprostmousea Chunet T.ehen; Strychnos mux-vomical; Acanthopanax senticosus (Rupr.et Maxim.)Harms; Rubia cordifolia L. Anti leukemic compounds, which were isolated from medicinal plants are ginsenoside Ro, ginsenoside Rh2, Emodin, Yuanhuacine, Aleemodin, phorbocdiester, Triptolide, Homolycorine, Atractylol, Colchicnamile, Paeonol, Aspargus polysaccharide A.B.C.D, Indirubin, Leonunrine, Acinosohic acid, Trichosanthin, Ge 132, Schizandrin, allicin, Indirubin, cmdiumlactone chuanxiongol, 18A glycyrrhetic acid, Kansuiphorin A 13 oxyingenol Kansuiphorin B. These investigation suggest that it may be very useful for developing more effective anti leukemic new dregs from medicinal plants.

Human Parechovirus: an Emerging Cause of Sepsis-Like Syndrome in Infants Aged under 3 Months

  • Roh, Da Eun;Kwon, Jung Eun;Kim, Yeo Hyang
    • Pediatric Infection and Vaccine
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    • v.27 no.2
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    • pp.102-110
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    • 2020
  • Purpose: This study aimed to investigate the clinical characteristics of human parechovirus (HPeV) infection in sepsis-like syndrome in infants aged under 3 months. Methods: Medical records of infants aged under 3 months with sepsis-like symptoms who were admitted between July 1, 2018 and August 31, 2018 were reviewed. A multiplex reverse transcription-polymerase chain reaction panel test was performed on the cerebrospinal fluid (CSF). Thirty-nine enrolled infants were categorized into three groups: 11 in group 1 (HPeV detected in the CSF), 13 in group 2 (enterovirus detected in the CSF), and 15 in group 3 (no virus detected in the CSF). Results: Compared with groups 2 and 3, a higher proportion of group 1 had tachycardia, tachypnea, apnea, and hypotension (P<0.05). A significantly lower white blood cell (WBC) count was noted in group 1 than in groups 2 and 3 (5,622±2,355/μL, 9,397±2,282/μL, and 12,312±7,452/μL, respectively; P=0.005). The CSF WBC count was lower in group 1 than in groups 2 and 3 (0.9±1.7/μL, 85.1±163.6/μL, and 3.7±6.9/μL, respectively; P=0.068). The proportion of patients requiring inotrope support (36.6% vs. 0% and 6.6%), mechanical ventilation (18.1% vs. 0% and 0%), and high flow nasal cannula (45.4% vs. 15.3% and 6.6%) was higher in group 1 than in groups 2 and 3. All patients recovered completely without complications. Conclusions: HPeV infection shows a severe clinical course and can cause a severe sepsis-like syndrome in infants aged under 3 months. Early diagnosis and proper treatment of HPeV infection are required.

Developmental Genetic Analysis of Avian Primordial Germ Cells and the Application to Poultry Biotechnology

  • Kagami, H.
    • Korean Journal of Poultry Science
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    • v.28 no.2
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    • pp.135-142
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    • 2001
  • A novel sterategy has been established to determine the origin of the Primordial Germ Cells (PGCs) in avian embryos directly and the developmental fate of the PGCs for the application to Poultry biotechnology. Cells were removed from 1) the centre of area pellucida, 2) the outer of area pellucida and 3) the area opaca of the stage X blastoderm (Eyal-Giladi & Kochav, 1976). When the cells were removed from the centre of area pellucida, the mean number of circulating PGCs in blood was significantly decreased in the embryo at stage 15 (Hamburger & Hamilton, 1951) as compared to intact embryos. When the cells were replenished with donor cells, no reduction in the PGCs number was observed. The removal of cells at the outer of area pellucida or at the area opaca had no effect on the number of PGCs. In case, another set of the manipulated embryos were cultured ex vivo to the hatching and reared to the sexual maturity, the absence of germ cells and degeneration of seminiferous tubules was observed in resulting chickens derived from the blastoderm in which the cells were removed from the centre of the area pellucida. It was concluded that the avian Primordial Germ cells are originated at the center of area pellucida. Developmental ability of the cells to differentiate into somatic cells and germ cells in chimeras were analyzed. Somatic chimerism was detected as black feather attributed from donor cells. Molecular identification by use of female - specific DNA was performed. It was confirmed that the donor cells could be differentiated into chimeric body and erythrocytes. Donor cells retained the ability to differentiate into germline in chimeric gonads. More than 70% of the generated chimeras transmitted donor derived gametes to their offspring indicating that the cells at the center of area pellucida had the high ability to differentiate into germ cells. A molecular technique to identify germline chimerism has been developed by use of gene scan analysis. Strain specific DNA fragments were amplified by the method. It would be greatly contributed for the detection of germline chimerism. Mixed- sex chimeras which contained both male and female cells were produced to investigate the developmental fate of male and female cells in ovary and testes. The sex combinations of donor and recipient of the resulting chimeras were following 4 pairs; (1) chimeras (ZZ/ZZ) produced by a male donor (ZZ) and a male recipient (ZZ), (2) chimeras (ZW/ZW) produced by a female donor (ZW) and a female recipient (ZW), (3) chimeras (ZZ/ZW) Produce by a male donor (ZZ) and a female recipient (ZW), (4) chimeras (ZW/ZZ) produced by a female donor (ZW) and a male recipient (ZZ). It was found that genetically male avian germ cells could differentiate into functional ova and that genetically female germ cells can differentiate into functional spermatozoa in the gonad of the mixed- sex chimeras. An ability for introduction of exogenous DNA into the PGCs from stage X blastoderms were analyzed. Two reporter genes, SV-$\beta$gal and RSV-GFP, were introduced into the PGCs. Expression of bacterial/gal was improved by complexing DNA with liposome detectedcc in 75% of embryos at 3 days embryos. At the embryos incubated for 1 day, expression of the GFP was observed all the embryos. At day 3 of incubation, GFP was detected in about 70% of the manipulated embryos. In case of GFP, expression of the transgene was detected in 30 %e of the manipulated embryos. These results suggested that the cells is one of the most promising vectors for transgenesis. The established strategy should be very powerfull for application to poultry biotechnology.

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Assessment of Water Quality in Pyeongtaek Reservoir and Its Main Tributaries (평택호와 유역 주요 하천의 수환경 및 오염도 평가)

  • Hwang, Soon-Jin;Cho, Kyung-Je;Shin, Jae-Ki
    • Korean Journal of Ecology and Environment
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    • v.36 no.1 s.102
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    • pp.38-47
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    • 2003
  • The water quality of the Pyeongtaek Reservoir and its main streams has been eval uated far water pollution state in March, June, September and December,2000. The following are the findings: $NH_4$ accounts for the majority of TN in the inflow streams. In the reservoir, TN and $NH_4$ are the more present in the winter season and less in the summer season, with $1.6{\sim}2.4$ times of $NO_3$ and $5.3{\sim}11.4$ times of $NO_2$ found in December and June compared with other seasons. The concentration of each component is different between streams: $NH_4$ among inorganic nitrogen has the highest concentration in the upstream, and $NO_3$ is more prevalent in the downstream. SRP accounts for $25{\sim}69%$ of TP in the stream. Unlike N component, P component in the reservoir rapidly decreases from upstream toward downstream, except in the summer. Average SRSi slightly increases in the fall, i.e., immediately after rainfall. In the streams, the average concentration of chlorophyll-a ranges from 9 to $33{\mu}g/l$, and is relatively high in the downstream. In contrast, in the reservoir, it is the highest in the upstream where $NH_4$ and SRP are frequently found. In particular, diatom and cryptomonad algae are bloomed in March, and blue-green algae in September; their maximum values are $108{\mu}g/l$ and $130{\mu}g/l$, respectively. Considering the concentration of N and P nutrients, pollution loads can affect the Pyeongtaek Reservoir in the downstream in this order: Ansong Stream

Ad libitum Pasture Feeding in Late Pregnancy Does Not Improve the Performance of Twin-bearing Ewes and Their Lambs

  • Corner-Thomas, R.A.;Back, P.J.;Kenyon, P.R.;Hickson, R.E.;Ridler, A.L.;Stafford, K.J.;Morris, S.T.
    • Asian-Australasian Journal of Animal Sciences
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    • v.28 no.3
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    • pp.360-368
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    • 2015
  • The present study evaluated the effect of controlled ryegrass-white clover herbage availability from day 128 until day 142 of pregnancy in comparison to unrestricted availability, on the performance of twin-bearing ewes of varying body condition score (BCS; 2.0, 2.5, or 3.0) and their lambs. It was hypothesised that under conditions of controlled herbage availability, the performance of lambs born to ewes with a greater BCS would be greater than those born to ewes with a lower BCS. During the period that the nutritional regimens were imposed, the pre- and post-grazing herbage masses of the Control regimen ($1,070{\pm}69$ and $801{\pm}30$ kg dry matter [DM]/ha) were lower than the ad libitum regimen ($1,784{\pm}69$ and $1,333{\pm}33kg\;DM/ha$; p<0.05). The average herbage masses during lactation were $1,410{\pm}31kg\;DM/ha$. Nutritional regimen had no effect on ewe live weight, BCS and back fat depth or on lamb live weight, indices of colostrum uptake, maximal heat production, total litter weight weaned or survival to weaning (p>0.05). The difference in ewe BCSs and back fats observed among body condition groups was maintained throughout pregnancy (p<0.05). At weaning, ewes from the BCS2.0 group had lower BCS and live weight ($2.4{\pm}0.2$, $74.3{\pm}2.6kg$) than both the BCS2.5 ($2.6{\pm}0.2$, $78.6{\pm}2.4kg$) and BCS3.0 ewes ($2.7{\pm}0.2$, $79.0{\pm}2.6kg$; p<0.05), which did not differ (p>0.05). Ewe BCS group had no effect on lamb live weight at birth or weaning or on maximal heat production (p>0.05). Serum gamma glutamyl transferase concentrations of lambs born to BCS3.0 ewes were higher within 36 hours of birth than lambs born to BCS2.0 ewes and BCS2.5 ewes ($51.8{\pm}1.9$ vs $46.5{\pm}1.9$ and $45.6{\pm}1.9IU/mL$, respectively [p<0.05]). There was, however, no effect of ewe body condition on lamb plasma glucose concentration (p>0.05). Lamb survival was the only lamb parameter that showed an interaction between ewe nutritional regimen and ewe BCS whereby survival of lambs born to BCS2.5 and BCS3.0 ewes differed but only within the Control nutritional regimen ewes (p<0.05). These results indicate farmers can provide twin-bearing ewes with pre- and post-grazing ryegrass-white clover herbage covers of approximately 1,100 and 800 kg DM/ha in late pregnancy, provided that herbage covers are 1400 in lactation, without affecting lamb performance to weaning. The present results also indicate that under these grazing conditions, there is little difference in ewe performance within the BCS range of 2.0 to 3.0 and therefore they do not need to be managed separately.

암환자 인식에 관한 연구 - 간호사ㆍ의사를 중심으로

  • Jo, In-Hyang
    • Korean Journal of Hospice Care
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    • v.2 no.1
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    • pp.58-74
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    • 2002
  • This paper constitutes a descriptive investigation and used a structured questionnaire to investigate nurses' and doctors' recognition of cancer patients. The subjects were extracted from the medical personnel working at the internal medicine, the surgery ward, the obstetrics and gynecology department, the pediatrics department, the cancer ward, and the emergency room of five general hospitals located in Seoul and Gyeonggi Province. The research lasted from August, 2001 to September 2001. Total 137 nurses and 65 doctors were included and made out the questionnaires directly distributed by the investigator. The study tool was also developed by the investigator and consisted of such items as the demographic and social characteristics, the medical personnel's recognition degree of cancer and cancer patients, their recognition of the management of cancer patients, and their participation in a hospice. The results were analyzed using the SPSS Window program in terms of technological statistics, ranks, t-test, and ANOVA. The reliability was represented in Cronbach' α=.75. The nurses' and doctors' recognition degree of cancer and cancer patients had an overall average of 3.86 at the 5 point-scale. The items that received an average of 4.0 or more included 'Medical personnel should explain about the cancer cure plans to the cancer patient and his or her family', 'A patient whose case has been diagnosed as a terminal cancer should be notified of it, 'If I were a cancer patient, I would want to get informed of it,' and 'Cancer shall be conquered whenever it is'. In the meantime, the items that received an average of 3.0 or less was 'My relationship with the cancer patient's family has gotten worse since I announced his or her impending death.' And according to the general characteristics and the difference test, the recognition degree of cancer and cancer patient was high among the subgroups of nurses, females, married persons, who were in their 30s, who had a family member that was a cancer patient, and who received a hospice education. The biggest number of the nurses and doctors saw 'a gradual approach over several days'(68.8%) as a method to tell a cancer patient about his or her cancer diagnosis or impending death. Those who usually tell tragic news were the physician in charge(62.8%), the family members or relatives(32.1%) and the clergymen(3.8%) in the order. The greatest number of them recommended a cancer patient's home as the place where he or she should face death because they thought 'it would stabilize his or her mentality'(91.9%) while a number of them recommended the hospital because they 'should give the psychological satisfaction to the patient'(40%) or 'should try their best until the last moment of the patient's death'(30%). A majority of the medical personnel regarded 'smoking or drinking' and 'diet' as the causes of cancer. The biggest symptom of a cancer patient was 'pain' and the pain management of a cancer patient was mostly impeded by the 'excessive fear of drug addiction, tolerance to drugs and side effects of drugs' by medical personnel, the patient, and his or her family. The most frequently adopted treatment plan of a terminal cancer patient was 'to do whatever the patient or his or her family wants' to resort to a hospice' and 'to continue active treatment efforts' in the order. The biggest reasons why a terminal cancer patient went to see a doctor were 'pain alleviation' 'control of symptoms other than pain(intravenous supply)' and 'incapability of the patient's family' in the order. Terminal cancer patients placed their major concern in 'spiritual(religious) matter' 'emotional matters' their family' 'existence' and 'physical matters' in the order. 113(58.5%) of the whole medical personnel answered they 'would recommend' an alternative treatment to a terminal cancer patient mostly because they assumed it would 'stabilize the patient's mentality.' Meanwhile, 80(41.5%) of them chose 'not to recommend it mostly due to the unverified effects and high cost of it(78.7%). A majority of them, I. e. 190(94.1%) subjects said they 'would recommend' a hospice to a terminal cancer patient mostly because they thought it would help the patient to 'mentally prepare'(66.6%) Only 17.3% of them, however, had received a hospice education, most of which was done through the hospital duty education(41.4%) and volunteer training(34.5%). The follows are results of this study: 1. The nurses and the doctors turned out to be still passive and experience confusion in dealing with a cancer patient despite their great sense of responsibility for him or her. 2.Nurses and Doctors realize the need of a hospice, but an extremely small number of them participate in a hospice education or performance. Thus, a whole recognition of a hospice should be changed, for which purpose a hospice education for nurses and doctors should be provided. 3.Terminal cancer patients preferred their home to a hospital as the place to face their impending death because they felt it would bring 'mental stability.' And most of nurses and doctors think it would be unnecessary for them to be hospitalized just for control of their symptoms. Accordingly a terminal cancer patient can be cared at home, and a home hospice care needs to be activated.

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A Study on Relationship between Physical Elements and Tennis/Golf Elbow

  • Choi, Jungmin;Park, Jungwoo;Kim, Hyunseung
    • Journal of the Ergonomics Society of Korea
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    • v.36 no.3
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    • pp.183-196
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    • 2017
  • Objective: The purpose of this research was to assess the agreement between job physical risk factor analysis by ergonomists using ergonomic methods and physical examinations made by occupational physicians on the presence of musculoskeletal disorders of the upper extremities. Background: Ergonomics is the systematic application of principles concerned with the design of devices and working conditions for enhancing human capabilities and optimizing working and living conditions. Proper ergonomic design is necessary to prevent injuries and physical and emotional stress. The major types of ergonomic injuries and incidents are cumulative trauma disorders (CTDs), acute strains, sprains, and system failures. Minimization of use of excessive force and awkward postures can help to prevent such injuries Method: Initial data were collected as part of a larger study by the University of Utah Ergonomics and Safety program field data collection teams and medical data collection teams from the Rocky Mountain Center for Occupational and Environmental Health (RMCOEH). Subjects included 173 male and female workers, 83 at Beehive Clothing (a clothing plant), 74 at Autoliv (a plant making air bags for vehicles), and 16 at Deseret Meat (a meat-processing plant). Posture and effort levels were analyzed using a software program developed at the University of Utah (Utah Ergonomic Analysis Tool). The Ergonomic Epicondylitis Model (EEM) was developed to assess the risk of epicondylitis from observable job physical factors. The model considers five job risk factors: (1) intensity of exertion, (2) forearm rotation, (3) wrist posture, (4) elbow compression, and (5) speed of work. Qualitative ratings of these physical factors were determined during video analysis. Personal variables were also investigated to study their relationship with epicondylitis. Logistic regression models were used to determine the association between risk factors and symptoms of epicondyle pain. Results: Results of this study indicate that gender, smoking status, and BMI do have an effect on the risk of epicondylitis but there is not a statistically significant relationship between EEM and epicondylitis. Conclusion: This research studied the relationship between an Ergonomic Epicondylitis Model (EEM) and the occurrence of epicondylitis. The model was not predictive for epicondylitis. However, it is clear that epicondylitis was associated with some individual risk factors such as smoking status, gender, and BMI. Based on the results, future research may discover risk factors that seem to increase the risk of epicondylitis. Application: Although this research used a combination of questionnaire, ergonomic job analysis, and medical job analysis to specifically verify risk factors related to epicondylitis, there are limitations. This research did not have a very large sample size because only 173 subjects were available for this study. Also, it was conducted in only 3 facilities, a plant making air bags for vehicles, a meat-processing plant, and a clothing plant in Utah. If working conditions in other kinds of facilities are considered, results may improve. Therefore, future research should perform analysis with additional subjects in different kinds of facilities. Repetition and duration of a task were not considered as risk factors in this research. These two factors could be associated with epicondylitis so it could be important to include these factors in future research. Psychosocial data and workplace conditions (e.g., low temperature) were also noted during data collection, and could be used to further study the prevalence of epicondylitis. Univariate analysis methods could be used for each variable of EEM. This research was performed using multivariate analysis. Therefore, it was difficult to recognize the different effect of each variable. Basically, the difference between univariate and multivariate analysis is that univariate analysis deals with one predictor variable at a time, whereas multivariate analysis deals with multiple predictor variables combined in a predetermined manner. The univariate analysis could show how each variable is associated with epicondyle pain. This may allow more appropriate weighting factors to be determined and therefore improve the performance of the EEM.

A Study on Teaching-Learning and Evaluation Methods of Environmental Studies in the Middle School (중학교 "환경" 교과의 교수.학습 및 평가 방법 연구)

  • 남상준
    • Hwankyungkyoyuk
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    • v.7 no.1
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    • pp.1-17
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    • 1994
  • This study was performed to determine appropriate teaching-learning and evaluation methods for Environmental Studies. To promote the relevance of our study to the needs of the schools and concerned educational communities of environmental education, we reviewed related literature, conducted questionnaire surveys, interviewed related teachers and administrator, held meetings with experts, and field-tested our findings. For selecting and developing teaching-learning methods of Environmental Studies, findings of educational research in general are considered. moreover, principles of environmental education, general aim of environmental education, orientations of environmental education, and developmental stages of middle school students in educational psychology were attended. In addition, relevance to the purpose of the Environmental Studies curriculum, appropriateness for value inquiry as well as knowledge inquiry, small group centered class organization, social interaction centered teaching-learning process, regional environmental situation, significance of personal environment, evaluation methods of Environmental Studies, multi- and inter-disciplinary contents of the Environmental Studies textbook, suitability to the evaluation methods of Environmental Studies, and emphasis on the social interaction in teaching-learning process were regarded. It was learned the Environmental Studies can be taught most effectively in via of holding discussion sessions, conducting actual investigation, doing experiment-practice, doing games and plate, role-playing and carrying out simulation activities, and doing inquiry. These teaching-learning methods were field-tested and proved appropriate methods for the subject. For selecting and developing evaluation method of Environmental Studies, such principles and characteristics of Environmental Studies as objective domains stated in the Environmental Studies curriculum, diversity of teaching-learning organization, were appreciated. We categorized nine evaluation methods: the teacher may conduct questionnaire surveys, testings, interviews, non-participatory observations; they may evaluate student's experiment-practice performances, reports preparation ability, ability to establish a research project, the teacher may ask the students to conduct a self-evaluation, or reciprocal evaluation. To maximize the effect of these methods, we further developed an application system. It considered three variables, that is, evaluates, evaluation objectives domains, and evaluation agent, and showed how to choose the most appropriate methods and, when necessary, how to combine uses of different methods depending on these variables. A sample evaluation instrument made on the basis of this application system was developed and tested in the classes. The system proved effective. Pilot applications of the teaching-learning methods and evaluation method were made simultaneously; and the results and their implications are as follows. Discussion program was applied in a lesson dealing with the problems of waste disposal, in which students showed active participation and creative thinking. The evaluation method used in this lesson was a multiple-choice written test for knowledge and skills. It was shown that this evaluation method and device are effective in helping students' revision of the lesson and in stimulating their creative interpretations and responces. Pupils showed great interests in the actual investigation program, and this programme was proved to be effective in enhancing students' participation. However, it was also turned out that there must be pre-arranged plans for the objects, contents and procedures of survey if this program is to effective. In this lesson, non-participatory observation methods were used with a focus on the attitudes of students. A scaled reported in general description rather than in grade. Experiment-practice programme was adopted in a lesson for purifying contaminated water and in this lesson, instruction objectives were properly established, the teaching-learning process was clearly specified and students were highly motivated. On the other hand, however, it was difficult to control the class when some groups of students require more times to complete their experiment, and sometimes different results. As regards to evaluation, performance observation test were used for assessing skills and attitudes. If teachers use well-prepared Likert scale, evaluation of all groups within a reasonablely short period of time will be possible. The most effective and successful programme in therms of students' participation and enjoyment, was the 'ah-nah-bah-dah-market' program, which is kind of game of the flea market. For better organized program of this kind, however, are essential, In this program, students appraise their own attitudes and behavior by responding to a written questionnaire. In addition, students were asked to record any anecdotes relating to self-appraisal of changes on one's own attitudes and behaviours. Even after the lesson, students keep recording those changes on letters to herself. Role-playing and simulation game programme was applied to a case of 'NIMBY', in which students should decide where to located a refuse dumping ground. For this kind of programme to e successful, concepts and words used in the script should be appropriate for students' intellectual levels, and students should by adequately introduced into the objective and the procedures of the lessons. Written questionnaire was used to assess individual students' attitudes after the lesson, but in order to acquire information on the changes of students' attitudes and skills, pre-test may have to be made. Doing inquiry programme, in which advantages in which students actually investigated the environmental influence of the areas where school os located, had advantages in developing students' ability to study the environmental problems and to present the results of their studies. For this programme to be more efficient, areas of investigation should be clearly divided and alloted to each group so that repetition or overlap in areas of study and presentation be avoided, and complementary wok between groups bee enhanced. In this programme, teacher assessed students' knowledge and attitudes on the basis of reports prepared by each group. However, there were found some difficults in assessing students' attitudes and behaviours solely on the grounds of written report. Perhaps, using a scaled checklist assessing students' attitudes while their presentation could help to relieve the difficulties.

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Chemical Age Dating of Zircon and Monazite by E1ectron Microprobe (전자현미분석기를 이용한 저어콘 및 모나자이트의 화학적 연대 측정법)

  • 이석훈
    • The Journal of the Petrological Society of Korea
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    • v.10 no.3
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    • pp.179-189
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    • 2001
  • The determination of trace concentration of U, Th and Pb was carried out for chemical dating of zircon and monazite by electron microprobe. Detection limit and error range should be considered to measure characteristic X-rays of M-line from those minerals, which are low in the ionization of atom and low peak intensity in the spectrum. The element of U, Th and Pb were simultaneously measured with 3 spectrometers equipped with PET crystal to reduce a total counting time and error due to drift of instrumental operating condition. Detection limit could be improved from increase of the peak/background ratio through adjusting pulse height analyzer about 1000 mv baseline. Under permissible maximum analytical conditions, theoretical detection limit of U, Th and Pb is down to 30 ppm (99% confidence level). The analytical result was maintained at a relative error $\pm$10% ($2{\sigma}$) in 800 ppm Pb, $\pm$5% ($2{\sigma}$) in 2330 ppm U and $\pm$10% ($2{\sigma}$) in dating from a single measurement of zircon at 15 keV and 100 nA. However, for the precise dating of zircon and monazite, if it is considered a 3 $\mu\textrm{m}$ spatial resolution, <100 ppm ($3{\sigma}$) detection limit and <$\pm$10% ($2{\sigma}$) relative error, optimum analytical conditions are given as 15~20 keV accelerating voltage, 100~200 nA beam current and 300~1200 sec total counting time. To reduce material damage by high current, there is need to be up to 3~5 $\mu\textrm{m}$ of electron beam diameter, or to use arithmetic average of multiple measuring at a shorter counting time. A younger or relatively low concentration rocks can be dated chemically by lower detection limit and improved precision resulted from increase of current and measuring time.

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