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Chemo-Mechanical Analysis of Bifunctional Linear DGEBA/Linear Amine (DDM, DDS) Resin Casting Systems (DGEBA/방향족 아민(DDM, DDS) 경화제의 벤젠링 사이의 관능기 변화가 물성 변화에 미치는 영향에 대한 연구)

  • 명인호;정인재;이재락
    • Composites Research
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    • v.12 no.4
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    • pp.71-78
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    • 1999
  • To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with diaminodiphenyl methane (DDM), diaminodiphenyl sulphone (DDS) in a stoichiometrically equivalent ratio. From this work, the effect of aromatic amine curing agents. In contrast, the results show that the DGEBA/DDS cure system having the sulfone structure between the benzene rings had higher values in the conversion of epoxide, density, shrinkage (%), glass transition temperature, tensile modulus and strength, flexural modulus and strength than the DGEBA/DDM cure system having methylene structure between the benzene rings, whereas the DGEBA/DDM cure system presented higher values in the maximum exothermic temperature, thermal expansion coefficient, and thermal stability. These results are caused by the relative effects of sulfone group having strong electronegativity and methylene group having (+) repulsive property and stem from the effect of the conversion ratio of epoxide group. The result of fractography shows that the each grain size of the DDM/DGEBA system with feather-like structure is larger than that of the DDS/DGEBA system.

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백악기 미국 걸프만 퇴적층의 지구조적, 퇴적학적, 석유지질학적 고찰 (A Review of Tectonic, Sedinlentologic Framework and Petroleum Geology of the Cretaceous U. S. enlf Coast Sedimentary Sequence)

  • Cheong Dae-Kyo
    • The Korean Journal of Petroleum Geology
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    • v.4 no.1_2 s.5
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    • pp.27-39
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    • 1996
  • In the Cretaceous, the Gulf Coast Basin evolved as a marginal sag basin. Thick clastic and carbonate sequences cover the disturbed and diapirically deformed salt layer. In the Cretaceous the salinities of the Gulf Coast Basin probably matched the Holocene Persian Gulf, as is evidenced by the widespread development of supratidal anhydrite. The major Lower Cretaceous reservoir formations are the Cotton Valley, Hosston, Travis Peak siliciclastics, and Sligo, Trinity (Pine Island, Pearsall, Glen Rose), Edwards, Georgetown/Buda carbonates. Source rocks are down-dip offshore marine shales and marls, and seals are either up-dip shales, dense limestones, or evaporites. During this period, the entire Gulf Basin was a shallow sea which to the end of Cretaceous had been rimmed to the southwest by shallow marine carbonates while fine-grained terrigengus clastics were deposited on the northern and western margins of the basin. The main Upper Cretaceous reservoir groups of the Gulf Coast, which were deposited in the period of a major sea level .rise with the resulting deep water conditions, are Woodbinefruscaloosa sands, Austin chalk and carbonates, Taylor and Navarro sandstones. Source rocks are down-dip offshore shales and seals are up-dip shales. Major trap types of the Lower and Upper Cretaceous include salt-related anticlines from low relief pillows to complex salt diapirs. Growth fault structures with rollover anticlines on downthrown fault blocks are significant Gulf Coast traps. Permeability barriers, up-dip pinch-out sand bodies, and unconformity truncations also play a key role in oil exploration from the Cretaceous Gulf Coast reservoirs. The sedimentary sequences of the major Cretaceous reseuoir rocks are a good match to the regressional phases on the global sea level cuwe, suggesting that the Cretaceous Gulf Coast sedimentary stratigraphy relatively well reflects a response to eustatic sea level change throughout its history. Thus, of the three main factors controlling sedimentation (tectonic subsidence, sediment input, and eustatic sea level change) in the Gulf Coast Basin, sea-level ranks first in the period.

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A Study on the Actual Conditions of Smoking in Middle and High School Students in One Region (일 지역 중·고등학생의 흡연실태)

  • Kim, Hyeon-Ok
    • Journal of the Korean Society of School Health
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    • v.12 no.1
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    • pp.149-167
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    • 1999
  • To investigate the actual conditions of smoking in middle and high school students in Chinan County, I used a sturctured questionnaire for 1,579 students attending twelve middle-high schools from December 1, 1998 to December 20, 1998. I collected and data correlated the using an $SPSS-PC^+$ 1. The smoking rate of middle-high schoo1 students in Chinan County was 17.9%, relatively high. This smoking rate was different according to the gender, grade, religion, and economic situation. In mals, high school students, non-religious, students low income family students, the smoking rate was higher. The smoking rate of high school students was almost the same as the smoking rate of adults, generally higher than that of foreign teenagers. Because the smoking rat of studinets in the third grade of middle school and in the first grade of high School was six times higher, increased education should be conducted during this time in an attempt to curb the sudden increase of the smoking rate. The smoking rate of girl students was 5.0%; this has increased mor than three times from ten years ago. Consequently, counter measures should be taken against the smoking of female students as well as juvenile smoking in general. In addition, the smoking rate of middle-high school students showed interesting differences when correnated with enviornmental factors. Students with low grades, who are not satisfied with school life, who don't have both parents, who have uncaring parents who nare too strict or too arbitary, who have smoking parents, or who have experienced smoking commonly smoked. Therefore, to lower the smoking rate we should improve the school environment, improve a student's interest in school life. And parents or siblings should lead by example and quit smoking at home. Schools should educate students more effectively concerning the harmful effects of smoking and create an accurate understanding of its dancers. From the beginning, we should teach students never ever to touch cigaretts. 2. The surve discovered that most students started out of curiosity, or solicitantion from friends or elders at middle school, and had been smoking one to five cigarettes for more than a year. They obtained cigarettes at stores and most of them have friends who smoke. As a result anti-smoking education should be conducted at elementary schools prior to middle school. More than 95% of the teenagers who smoke had friends who smote and smoked out of curiosity or the recommendation of elders. Thus, we must focus on teenagers who smoke in group, rather than individually. Fuyrthermore, the strict application of the regulation of tobacco sales as well as tobacco cooperation from retailers are needed. While students did not show any mood or academic achievement difference after beginning smoking, 58.1% of the students a health situdation that was worse. Juvenile smoking is more harmful to the juvenile than adult smoking is to the adult. This should be focused on in an anti-smoking campaign. 3. Students who smoke hada more positive attitude toward smoking than students who don't smoke. Students who smoke had a tendency to have a nuetral position and are not concerned about smoking compared to non-smoking students. The survey showed that the great number of students had a nuetral position. Because this nuetrality may increase Juvenile smoking, education that provides an exact understanding of smoking should be performed to build the correct attidude toward smoking. 4. Middle school students smoke when angry, gloomy, anxious, a lone and when they have some problems to solve, on when they feel inconveniened in other wores, they smoke to reliver stress. They also smok due to addiction. Because smoking is not a praetical method to relieve stress, a program which helps to acquire positive relief stress should be provided to help reduce smoking. 5. About 65% of students who smoke want to quit smoking because of health problem, 78% of them have tried mor than once to quit but failed due to weak will power and peer pressure from friends who smoke. Juvenile smoking is group, oriented. Thus, the program that advances less smoking will be the one that focuseds on groups. 6. As for advice to students who want to quit smoking, "persuasion" was used most commonly, followed by a "presentation on how to quit smoking". Another method were severe punishment. About 70% of the students wanted the anti-smoking guide at school. 7. Most students (73.5%) had a position that more anti-smoking education at school is needed. Obriously, then, anti-smoking education at middle-high schools should be reinfoced. Although the education which explains the harmful influence of tobacco is known as an efficient way prevent smoking; it does not influence students who already smoke. Therefore, for students who smoke, multi-dimensional approaches must be attempted that include physical training, phychokogical approache, consultation and discussion, medical chek-ups, audio-visual education technigues, and professonal instructors, in addition, because smoking students have more negative on lukewarm attitude to anti-smoking education anti-smoking education should be conducted through a communicative style by dedicated teachers who care about students. In order to increase the effectiveness of this program.

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The Dynamic and Histologic Changes of Variously Fixed Bovine Pericardiums Specimens after Mechanical Fatigue Stimuli (다양한 고정 처리법을 이용한 소 심낭의 기계적 피로 자극 후 역학적 및 조직학적 변화)

  • Chang, Hyoung-Woo;Kim, Yong-Jin;Kim, Soo-Hwan;Park, Ji-Eun;Park, Chun-Soo;Kim, Woong-Han;Kim, Kyung-Hwan
    • Journal of Chest Surgery
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    • v.42 no.2
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    • pp.148-156
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    • 2009
  • Background: As cardiovascular operations become more complex and sophisticated, there is an increasing need for various bioprostheses for use as components of blood vessels and heart valves. We developed a fatigue stimuli test instrument to objectively evaluate the mechanical durability of a bioprosthesis, and we tested several currently known processing methods for bovine pericardium and we then compared the results. Material and Method: Fresh bovine pericardium was collected at the butcher shop with using aseptic technique, and each piece of pericardium was fixated and/or decellularized by 16 representative methods. We measured the permeability and compliance of the processed bovine pericardium samples, and measured them again after exposure to the fatigue stimuli. All the pieces of pericardium underwent microscopic examinations before and after the fatigue stimuli. Result: A mixture of glutaraldehyde and solvent treatment showed better mechanical durability than did the single glutaraldehyde treatment. High concentration glutaraldehyde treatment showed equal or no worse results than did low concentration glutaraldehyde treatment. After SDS (sodium dodecylsulfate) decellularization, the mechanical property of the bioprosthesis became much worse ($20{\sim}190$ times) and the mechanical durability to the fatigue stimuli was also very poor. Conclusion: We obtained the basic durability data after various fixation methods with using a home-made fatigue test instrument.

Environmental Assessment for Acid Mine Drainage by Past Coal Mining Activities in the Youngwol, Jungseon and Pyungchang areas, Korea (영월, 정선 및 평창지역 폐 석탄광 산성광산배수의 환경오염 평가)

  • 정명채
    • Economic and Environmental Geology
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    • v.36 no.2
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    • pp.111-121
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    • 2003
  • The objective of this study is to investigate the physical and chemical properties for environmental assessment of water system affected by acid mine drainage (AMD) from coal mining activities in the Youngwol, Jungseon and Pyungchang areas in Korea. During November 2000 to July 2002, 6 times of water samples were collected season-ally from acid mine drainage and nearby streams at 13 coal mines in the study area. The physical and chemical properties including pH, Eh, TDS, salinity, bicarbonates and DO were measured in the field. Eighteen cations includ-ing Al, Ca, Fe, Mg, Mn and Zn, and 6 anions including nitrates and sulfates were also analyzed by ICP-AES and If, respectively. Acid water from the Jungam coal mine has typical characteristics of AMD with very low pH(3∼4) and high TDS(1,000∼5,000 mg/1). Relatively high concentrations(mg/kg) of heavy meals, especially for Al(380), Fe(80), Mn(44) and Zn(8), were found in water samples from the Jungam coal mine area. Water samples from the Seojin, Sebang and Sungjin coal mines also contained over 50 mg/l of Al, >100 mg/1 of Fe and )10 mg/1 of Mn. In addition to anioins, over 1,000 mg/l of sulfate was found in several water samples. Seasonally, the concentrations of metals and sulfates varied; wet season samples were relatively higher in metals and sulfates than dry season samples. It is needed to establish the proper remediation and environmental monitoring of the AMD continuously.

Electricity Production Performance of Single- and Dual-cathode Microbial Fuel Cells Coupled to Carbon Source and Nitrate (Single-cathode와 Dual-cathode 미생물연료전지의 탄소원과 질산성질소의 전류발생 특성)

  • Jang, Jae-Kyung;Lee, Eun-Young;Ryou, Young-Sun;Lee, Sung-Hyoun;Hwang, Ji-Hwan;Lee, Hyung-Mo;Kim, Jong-Goo;Kang, Youn-Koo;Kim, Young-Hwa
    • Microbiology and Biotechnology Letters
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    • v.39 no.4
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    • pp.382-386
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    • 2011
  • Microbial fuel cells (MFC), devices that use bacteria as a catalyst to generate electricity, can utilize a variety of organic wastes as electron donors. The current generated may differ depending on the organic matter concentrations used, when other conditions, such as oxidant supply, proton transfer, internal resistance and so on, are not limiting factors. In these studies, a single-cathode type MFC (SCMFC) and dual-cathode type MFC (DCMFC) were used to ascertain the current's improvement through an increase in the contact area between the anode and the cathode compartments, because the cathode reaction is one of the most serious limiting factors in an MFC. Also an MFC was conducted to explore whether an improvement in electricity generation resulted from oxidizing the carbon sources and nitrates. About 250 mg $L^{-1}$ sodium acetate was fed to an anode compartment with a flow rate of 0.326 mL $min^{-1}$ by continuous mode. The current generated from the DCMFC was higher than the value produced from MFC with a single cathode. COD removal of dual-cathode MFC was also higher than that of single-cathode MFC. The nitrate didn't affect current generation at 2 mM, but when 4 and 8 mM nitrate was supplied, the current in the single-cathode and dual-cathode MFC was decreased by 98% from $5.97{\pm}0.13$ to $0.23{\pm}0.03$ mA and $8.40{\pm}0.23$ to $0.20{\pm}0.01$ mA, respectively. These results demonstrate that increasing of contact area of the anode and cathode can raise current generation by an improvement in the cathode reaction.

Risk Factors Affecting Severity of Menopausal Symptoms in Early and Late Postmenopasusal Woman (초기와 후기 폐경후기 여성에서의 폐경기 증상의 심각도와 위험 요인들)

  • Kim, Jong-Hun;Lee, Moon-Soo;Yang, Jae-Won;Ko, Young-Hoon;Ko, Seung-Duk;Joe, Sook-Haeng
    • Korean Journal of Psychosomatic Medicine
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    • v.17 no.2
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    • pp.52-61
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    • 2009
  • Objectives : The aim of this study was to assess health-related quality of life and evaluate the risk factors affecting severity of menopausal symptoms in early and late postmenopausal women based on the stages of reproductive aging workshop(STRAW) paradigm. Methods : This cross-sectional study examined 497 Korean postmenopausal women aged 41-59 years in Seoul and Gyeonggi province. We divided subjects into early postmenopause group and late postmenopause group. Menopause Rating Scale(MRS) was used to measure the quality of life. MRS scores, sociodemographic variables, smoking, alcohol use, age at menopause, and risk factors such as attitude to menopause, depression, history of premenstrual dysphoric disorder were compared between early and late postmenopause groups. Multiple regression analysis was performed in each group to assess the independent contribution of several variables. Results : Early postmenopause group showed significantly higher MRS scores, more negative attitude toward menopause, higher scores of depressive symptoms than late postmenopause group. Moderate to very severe hot flush group showed significantly, more negative attitude toward menopause, higher score of depressive symptoms, and higher MRS scores than none to mild hot flush groups. Depressive symptoms and attitude toward menopause contributed to the severity of menopausal symptom in both early and late postmenopause groups. Chronological age, age at menopause, history of PMDD contributed to severity of menopausal symptoms in early postmenopause group while marital status and occupation contributed in late postmenopause group. Conclusion : Health-related quality of life in postmenopause women was significantly lower in early postmenopause group than the late. Attitude toward menopause and depressive symptoms contributed significantly to quality of life in both early and late postmenopause groups but other variables contributed differently in each group. Further studies on clinical samples of postmenopausal women in order to confirm quality of life and its risk factor are needed to be done.

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The Roles of Excitatory Amino Acid System in the Organophosphate-induced Brain Damage (유기인제에 의한 뇌 손상에 있어서 흥분성 아미노산의 역할)

  • Ko, Bong-Woo;Park, Eun-Hae;Kim, Dong-Sik;Bang, Sung-Hyun;Jin, Joo-Yeon;Kim, Dae-Sung;Ju, Chang-Wan;Lee, Kyung-Kap;Cho, Moon-Jae;Kimcho, So-Mi;Lee, Bong-Hee;Riu, Key-Zung;Park, Min-Kyoung;Lee, Young-Jae
    • Applied Biological Chemistry
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    • v.44 no.3
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    • pp.148-152
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    • 2001
  • This study investigated the role of excitatory amino acid systems in the initiation of organophosphate-induced seizures and brain damages in rats through quantitative in vivo microdialysis. Microdialysates were collected from the hippocampus of rat brain, treated with diisopropylfluorophosphate (DFP; 2.67 mg/kg, s.c.) alone, and/or atropine sulfate (15 mg/kg, i.m.) and procyclidine (30 mg/kg, i.m.). The protective effects of atropine, a muscarinic blocker, and/or procyclidine, a N-methyl-D-aspartate and cholinergic antagonist, against DFP were examined. DFP treatment increased the levels of aspartate (Asp) and glutamate (Glu) significantly in the hippocampal persuate with the induction of seizures. Treatment of procyclidine could effectively block the increase of Asp and Glu levels. Atropine treatment showed no significant anticonvulsive effects against DFP-induced seizures. The increases of Asp and Glu levels by DFP were also completely blocked through the combined treatment of atropine and procyclidine. Histopathological findings on the hippocampus confirmed the above results. More effective protection was observed through the treatments of procyclidine alone or of both procyclidine and atropine than atropine alone against DFP-induced brain damage. Procyclidine was shown to be effective in DFP-induced seizures.

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Studies on LED Wavelength to Enhance Growth and Bio-active Compounds of Carrots (당근의 성장과 생리활성물질 함량을 증진시키는 LED 파장에 관한 연구)

  • Kang, Suna;Kim, Min-Jung;Kim, Bong Soo;Park, Sunmin
    • Journal of Applied Biological Chemistry
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    • v.58 no.2
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    • pp.131-137
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    • 2015
  • Commercial greenhouse plant factories are highly efficient for controlling external factors such as floods, drought, insects, air pollution etc. However, they require substantial startup & maintenance investments and experimental research to optimize production. These facilities are especially useful for urban farming where high efficiency in small spaces is required. In this study, we investigated whether light emitting diode (LED) lights with mixed dominant wavelengths (650 nm : 550 nm : 445 nm=8:1:1, 650 nm : 445 nm=6:4) can increase the growth rate and bio-active compound content of carrots in comparison to that of fluorescent light (FL). LED with mixed wavelength (650 nm : 550 nm : 445 nm=8:1:1) increased the total weight and root circumference of carrots compared to FL. However, ${\beta}$-carotene contents were not significant in LED (650 nm : 550 nm : 445 nm=8:1:1). However, LED (650 nm : 445 nm=6:4) increased the ${\beta}$-carotene (FL: 7.27, LED: 10.48 mg/g ${\beta}$-carotene dried weight). These results suggested that using LED light at the ideal wavelength, at the antithesis color of the plant, might enhance plant growth and bio-active compound contents.

On the Secretion and Functions of Equine Chorionic Gonadotropin (말의 융모성 성선자극 호르몬의 분비와 기능)

  • Min, K.S.
    • Korean Journal of Animal Reproduction
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    • v.24 no.2
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    • pp.125-142
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    • 2000
  • 13). Analysis of a purified preparation of eCG revealed that its $\beta$ -subunit consists of 149 amino acids, which was confirmed by the molecular cloning of its cDNA. There seem to be at least four to six, or even as many as 11, O-glycosylation sites on the extended C-tenninal region of the eCG $\beta$-subunit. Interestingly, eCG is a unique member of this family, as it appear to be a single molecule that possesses both LH- and FSH-like activities. Using the cDNA prepared from mRNA extracted from equine placental and pituitary tissues, we cloned the cDNA of eCG $\alpha$- and $\beta$ -subunits and eFSH $\beta$ -subunit. The mRNA expression of each subunit seems to be independently regulated, which may account for differences in the quantities of $\alpha$ - and $\beta$ -subunits in the placenta and pituitary. Thus, eCG is a distinct molecule from the view points of its biological function and glycoresidue structures. Recombinant eCGs including the mutants which lack oligosaccharides will be useful tools for analyzing the structure-function relationships of gonadotropins in the horse as well as other species. Similar experiments will also clarify the proposed structure and biological functions for the glycoprotein hormones. These experimental are now possible, and hopefully a resolution of the existing controversy will be forthcoming in the near future.

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