• Korean Journal of Materials Research
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• 제4권8호
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• pp.906-914
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• 1994

Plastic behavior of two-phase intermetallic compounds based on $LI_{2}$-type $(Al, Cr)_3$ Ti was investigated using compression test at R.T. and 77K. $LI_{2}$ single phase alloys and two-phase alloys consisting of mainly $LI_{2}$ phase and a few or 20% second phases were selected from AI-Ti-Cr phase diagram. In general, compared with Llz single phase, two-phase alloys consisting of 20% second phase showed relatively high yield strength and poor ductility. Among the alloys, however, AI-21Ti-23Cr alloy consisting of 20% $Cr_{2}Al$ phase showed available ductility as well as high yield strength. Plastic behavior of $LI_{2}$ single phase alloys and two-phase alloys consisting of a few% $Cr_{2}Al$ was also investigated. Homogenization of arc melted ingots substantially reduced the amount of second phases but introduced extensive pore. When Cr content increased in $Ll_{2}$ single phase alloys after the homogenization, the volume fraction of pore in the alloys decreased, and no residual pore was observed in two-phase alloys consisting of a few% $Cr_{2}Al$ phase. Environmental effect on the ductility of the alloys was investigated using compression test at different strain rates($1.2 \times 10^{-4}/s$ and $1.2 \times 10^{-2}/s$). Environmental embrittlement was least significant in A1-25Ti-10Cr alloy consisting of LIZ single phase among the alloys tested in this study. However, based on the combined estimation of the pore formation, environmental embrittlement and ingot cast structure, AI-21Ti-23Cr alloy consisting of 20% $Cr_{2}Al$ as the second phase is expected to show the best tensile elongation behavior.

• Journal of the Korea Concrete Institute
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• 제21권3호
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• pp.245-253
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• 2009

The importance of chloride ions in the corrosion of steel in concrete has led to the concept for chloride threshold level (CTL). The CTL can be defined as the content of chlorides at the steel depth that is necessary to sustain local passive film breakdown and hence initiate the corrosion process. Despite the importance of the CTL, due to the uncertainty determining the actual limits in various environments for chloride-induced corrosion, conservative values such as 0.4% by weight of cement or 1.2 kg in 1 $m^3$ concrete have been used in predicting the corrosion-free service life of reinforced concrete structures. The paper studies the CTL for blended cement concrete by comparing the resistance of cementitious binder to the onset of chloride-induced corrosion of steel. Mortar specimens were cast with centrally located steel rebar of 10 mm in diameter using cementitious mortars with ordinary Portland cement (OPC) and mixed mortars replaced with 30% pulverized fuel ash (PFA), 60% ground granulated blast furnace slag (GGBS) and 10% silica fume (SF), respectively, at 0.4 of a free W/B ratio. Chlorides were admixed in mixing water ranging 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, 2.0, 2.5 and 3.0% by weight of binder(Based on $C1^-$). Specimens were curd 28 days at the room temperature, wrapped in polyethylene film to avoid leaching out of chloride and hydroxyl ions. Then the corrosion rate was measured using the polarization resistance method and the order of CTL for binder was determined. Thus, CTL of OPC, 60%GGBS, 30%PFA and 10%SF were determined by 1.6%, 0.45%, 0.8% and 2.15%, respectively.

• Geophysics and Geophysical Exploration
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• 제8권4호
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• pp.262-269
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• 2005

Since the buried cultural relics are three-dimensional (3-D) objects in nature, 3-D survey is more preferable in archeological exploration. 3-D Ground Penetrating Radar (GPR) survey based on very dense data in principle, however, might need much higher cost and longer time of exploration than other geophysical methods commonly used for the archeological exploration, such as magnetic and electromagnetic methods. We developed a small-scale continuous data acquisition system which consists of two sets of GPR antennas and the precise positioning device tracking the moving-path of GPR antenna automatically and continuously. Since the high cost of field work may be partly attributed to establishing many profile lines, we adopted a concept of data acquisition at arbitrary locations not along the pre-established profile lines. Besides this hardware system, we also developed several software packages in order to effectively process and visualize the 3-D data obtained by the developed system and the data acquisition concept. Using the developed system, we performed 3-D GPR survey to investigate the possible historical remains of Baekje Kingdom at Buyeo city, South Korea, prior to the excavation. Owing to the newly devised system, we could obtain 3-D GPR data of this survey area having areal extent over about $17,000m^2$ within only six-hours field work. Although the GPR data were obtained at random locations not along the pre-established profile lines, we could obtain high-resolution 3-D images showing many distinctive anomalies, which could be interpreted as old agricultural lands, waterways, and artificial structures or remains. This cast: history led us to the conclusion that 3-D GPR method is very useful not only to examine a small anomalous area but also to investigate the wider region of the archeological interests.

• Korean Journal of Veterinary Research
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• 제27권2호
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• pp.277-290
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• 1987

This paper dealt with etiological studies on the acute fatal disease of Angora rabbits occurring as a group in Korea. The disease was confirmed as an acute infectious disease caused by virus. The results obtained were summarized as follows: The disease produced a high morbidity in the rearing Angora rabbits and a high mortality in the infected rabbits, and was acute. The infected rabbits died soon without premonitory signs after inappetence. The body temperature of the affected rabbits rose to $40^{\circ}C$ and nearly all deaths occurred within 48 hours after inoculation. In many cases a bloody foam was visible from the nostrils after death. According to the progress of the disease the nervous signs, such as ataxia, paralysis of the legs, and torticollis could be recognized in the some cases. Rabbits that had recovered from the disease were severe emaciation, and bristly and sparse hairs. In macroscopical findings, there were hemorrhage and edema of the lung, hemorrhage or hyperemia of the tracheal and broncheal mucosae, appearance of blood-tinged effusion in the respiratory tract. The principal lesions were found in the liver. Usually the lobular necrosis of the liver cells was progressed, and focal necrosis and hemorrhagic spots of various sizes were often observed in the liver. Liver was as a whole pale. In chronic cases, however, there was a slight liver cirrhosis with the atrophy of the parenchymal cells. The other lesions encountered grossly consisted of swelling and petechiae of the kidney, hyperemia and hemorrhage of the spleen, catarrh of the small intestine, and hyperemia of the brain. The urinary bladder contained a lot of turbid urine or bloody urine and urinary cast, and was distended with the urine. In microscopical findings, the most striking lesions occurred in the liver and may be classified as viral hepatitis. The hepatic lesions were initially characterized by progression from periportal to peripheral necrosis of the lobules with the infiltration of mononuclear cells. Focal necrosis of various sizes, hemorrhage and hyperemia were often observed in the hepatic lobules. In chronic cases, there were intensive infiltration of lymphocytes, proliferation of fibroblasts, appearance of plasmal cells, and atrophy of parenchymal cells in the hepatic tissue. Perivascular lymphocytic infiltration and meningitis were seen in the brain and spinal cord. In the kidney, there were acute glomerulonephritis, hemorrhage, necrosis of the uriniferous tubules, and retention of eosinophilic substance within the renal tubules. Proliferation of fibroblasts and infiltration of mono-nuclear cells were found in the interstitial stroma of the kidney in chronic case. There were also hemorrhage and edema in the lung, hyperemia and hemorrhage in the trachea and bronchus, perivascular lymphocytic infiltration and focal myocardial necrosis in the heart, hyperemia and hemorrhage in the spleen, vacuolization and desquamation of mucous epithelia in the urinary bladder, catarrhal inflammation of the small intestine, hemorrhage in the adrenal cortex and hyperemia in the other organs. In the electron microscopical findings of the hepatic tissue, crystals of viral particles appeared in the cytoplasm of the hepatocytes and the sinusoidal endothelial cells, and the viral particles, were small in size and polygonal. The authors suppose the virus may belong to picornaviridae family of RNA viruses. Also immature virus-like particles, dilated rough endoplasmic reticulum and destruction of nuclear membrane were seen in the hepatocytes. From these results, it is concluded that the sudden death is an acute viral disease characterized by hepatitis and the affected rabbits may be died of viremia.

• Journal of Korean Academy of Nursing
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• 제10권1호
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• pp.41-55
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• 1980

The medical care insurance system, being put into practice nearly for three years, seem to have brought about some considerable problems as serious for the government as to consider a revision of that system. As one of the most serious problems of present system, the treatment cost of insurance patients is so remarkably low in comparison with than of non-insurance cases that normal operation of hospitals is threatened and care services of low quality are induced. The researcher carried out this survey to analyze and bring to light several aspects of treatment cost of non-insurance patients as a material for a re-assessment of the cost of insurance cases which shows a a considerable difference in amount at the standpoint of hospitals with than of non-insurance cases and further, hoping the significant blind spot of present insurance system(that is, the absence of regulations' for cost assessment by patterns or types of health care treatment) will be mended in near future. The survey was carried out with the treatment invoice sheets of total 902 in-hospital Patients of a general hospital in Seoul during the period of the 2 nd quarter of the year(1979). Among total 902 patients, 694 cases were used for analysis, because those disease or syndromes shared by less than 10% of the patients were put aside before procession. The data were analyzed by kinds or types of diseases, demographic characteristics of patients, hospitalization patterns, types of nursing treatment, etc. The result of analysis was as follows 1. Among all the non-insurance cases, those who received one or more kinds of nursing treatment mounted up to 96. 7 ％. The invoice issue frequency per person was 7.2 times, while that frequency per day for a person was 0.8, : the treatment cosr per person was ￦22,650 while its daily average was ￦2,430, due to the average 9.3 in-hospital days per person. 2. As to the nursing treatment types by the demographic characteristics of patients and hospitalization patterns. a. The unit cost female patients was generally more expensive them that of males, and independent nursing service was more given than other types of treatment. As to age, higher age groups received independent nursing service most, while the youngest group received instrumental and integrated nursing services. b. As to room grade, the unit cost of I.C.U. cases was the highest : and the cast of private room patients was higher than that of public room patients. By in-hospital days, the curve of function showed L. type : that is, the longer stay, the lower function. 3. State of treatment types by kinds of disease were ; a. Dependent nursing service showed comparatively high availability in surgical and neurologic disease and independent nursing service was most received by medical, obstetrical and urological patients, while instrumental and integrated services were most available for respiratory disease and obstetrical and neurologic diseases next. b. The invoice issue frequency per day for a patient was highest in obstetrical disease 3.8 times, and the unit cost(per one invoice sheet) was also highest in obstertrical disease(￦10,880) and next in neurologic cases(￦ 4,690 ). 4. As to the pertained departments. a. Cost amount per person was highest in department of Psychiatries daily cost was highest in obstetrical cases : while the invoice issue frequency was highest in obstetrics and next in pediatrics. b. In departments in need of surgical operation, dependent nursing care was highly availabl : while in internal medicine and obstetrics, independent service was higher. Psychiatrics showed the highest the of integrate nursing while pediatrics and obstetrics higher of instrumental services. The variation co-efficien of treatment cost came out to be relatively in high in special surgery, opthalmology and internal medicine. 5. State of treatment cost by types of nursing behavior was. a. The average frequency of invoice issue was 3.5 (times). Among the type four types of treatment, instrumetal service (4.3) and independent nursing behavior(3.9) showed higher frequency than average respectively. But as to unit cost (per invoice). dependent (￦5,200) and integrated (￦5,340) nursing care services were higher than average and considerably higher than the other two types. b. In repect patient distribution. independent nursing behavior(80.3% ) was the highest and depend ent nursing (31.7% ) the lowest. The variation co-efficient of treatment cost appeared highest in dependent nursing be havior as a whole, and among that, doctor's diagnosis showed the highest coefficient value (100.7). In conclusion, the variaty of treatment cost(treatment itself ) by various characteristics and treatment types pro- that treatment various sort of patients and treatment cost of various types of nursing behavior cannot be uniform. Therefore, to attain the equalization of health care service and its cost both for insurant and non-insurant patients, a more specific provision for assessment of cost should be added to the present medical care insurance system and, in addition, the cost of nursing treatment is desired to be inserted into the treatment invoice.

• Journal of the korean academy of Pediatric Dentistry
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• 제30권3호
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• pp.502-509
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• 2003

After 800 students of Chonbuk National University was examined, 86 people (male : 43, female : 43, mean age : 22.2 years old) was selected as a group of normal occlusion. From their gypsum cast, this conclusion was obtained. 1. Intra-observer measurement errors in buccolingual diameter, maxillary lateral incisors have somewhat bigger errors. In mesiodistal diameter, maxillary first molars and maxillary second molar have bigger numerical value. Mean errors of measurement are 0.051mm at buccolingual diameter of crown and 0.083mm at mesiodistal diameter. 2. Fluctuating asymmetry is 0.030 average in buccolingual diameter, and 0.037 average in mesiodistal diameter. Statistically there are no big differences. 3. Male has longer buccolingual diameter than female in every permanent teeth. Teeth which have statistical difference in buccolingual diameter are maxillary lateral incisor, maxillary canine, maxillary second molar, mandibular central incisor, mandibular canine, mandibular second premolar, and mandibular first molar. In mesiodistal diameter maxillary central incisor, maxillary canine, and mandibular first molar have statistically difference. 4. Tooth which has the biggest difference depending on gender is maxillary lateral incisor in buccolingual diameter and mandibular canine in mesiodistal diameter. 5. Both sexes have similar crown index. Male has bigger value of crown module measurement and crown area measurement in every tooth. Crown area considered as size of tooth from occlusal surface was bigger in male than in female statistically except some teeth, maxillary first premolar, mandibular lateral incisor, first premolar and second premolar.

• Journal of Korean Orthopaedic Sports Medicine
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• 제5권1호
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• pp.69-74
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• 2006

Purpose: To perform the retrospective analysis of the sports injuries sustained by the college Taekwondo athletes in the respect of the injury patterns, mechanism of injury and clinical outcome Materials and Methods: This study is based on 47 out of 49 college Takwondo athletes, who had experienced the Takwondo related musculoskeletal injuries severe enough to visit the clinic for medical treatment. The mean age at the time of injury was 18.8 years and 39 were males and 8 females. The Taekwondo career was average 9.6 years and the injuries were sustained at average 6.7 years of their career. The injuries were analyzed by the detailed interview with thorough physical examination. Results: Forty-seven Taekwondo athletes in the study experienced average 1.8 injury/person (total 85 cases) with 26 persons of one time experience(55.3%), 11 persons of 2 times(23.4%),4 persons of 3 times (8.5%),5 persons of 4 times (10.6%) and 1 person of 5 times (2.2%). Injuries occurred during training in 50 cases (58.8%), while during match in 35 cases (41.2%). Injuries occurred during the attack phase of the match are 26 cases (31.7%) while 49 cases (57.6%) during the defense phase. As for the pattern of injury, fracture was the most common with 49 cases (57.6%), followed by ligament injury with 21 cases (24.7%). The upper extremity injuries were 32 cases (37.7%) while the lower extremity injuries were 44 cases (51.8%) Mode of medical treatment were operation in 15cases(17.7%), cast in 21 cases(24.7%), splint in 33 cases (38.8%), physical therapy in 15cases(17.7%) and acupuncture in 1 case(1.1%) Conclusion: Almost all the college Taekwondo athletes (96%) experienced sports injuries severe enough to receive medical treatments with the fracture being the most common injury pattern. The injuries occurred more commonly during the defense phase of the competition.

• The Mathematical Education
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• 제24권2호
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• pp.105-116
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• 1986

For any thought and knowledge, its growth and development has close relation with the society where it is developed and grow. As Feuerbach says, the birth of spirit needs an existence of two human beings, i. e. the social background, as well as the birth of body does. But, at the educational viewpoint, the spread and the growth of such a thought or knowledge that influence favorably the development of a society must be also considered. We would discuss the goal and the function of mathematics education in relation with the prosperity of a technological civilization. But, the goal and the function are not unrelated with the spiritual culture which is basis of the technological civilization. Most societies of today can be called open democratic societies or societies which are at least standing such. The concept of rationality in such societies is a methodological principle which completes the democratic society. At the same time, it is asserted as an educational value concept which explains comprehensively the standpoint and the attitude of one who is educated in such a society. Especially, we can considered the cultivation of a mathematical thinking or a logical thinking in the goal of mathematics education as a concept which is included in such an educational value concept. The use of the concept of rationality depends on various viewpoints and criterions. We can analyze the concept of rationality at two aspects, one is the aspect of human behavior and the other is that of human belief or knowledge. Generally speaking, the rationality in human behavior means a problem solving power or a reasoning power as an instrument, i. e. the human economical cast of mind. But, the conceptual condition like this cannot include value concept. On the other hand, the rationality in human knowledge is related with the problem of rationality in human belief. For any statement which represents a certain sort of knowledge, its universal validity cannot be assured. The statements of value judgment which represent the philosophical knowledge cannot but relate to the argument on the rationality in human belief, because their finality do not easily turn out to be true or false. The positive statements in science also relate to the argument on the rationality in human belief, because there are no necessary relations between the proposition which states the all-pervasive rule and the proposition which is induced from the results of observation. Especially, the logical statement in logic or mathematics resolves itself into a question of the rationality in human belief after all, because all the logical proposition have their logical propriety in a certain deductive system which must start from some axioms, and the selection and construction of an axiomatic system cannot but depend on the belief of a man himself. Thus, we can conclude that a question of the rationality in knowledge or belief is a question of the rationality both in the content of belief or knowledge and in the process where one holds his own belief. And the rationality of both the content and the process is namely an deal form of a human ability and attitude in one's rational behavior. Considering the advancement of mathematical knowledge, we can say that mathematics is a good example which reflects such a human rationality, i. e. the human ability and attitude. By this property of mathematics itself, mathematics is deeply rooted as a good. subject which as needed in moulding the ability and attitude of a rational person who contributes to the development of the open democratic society he belongs to. But, it is needed to analyze the practicing and pursuing the rationality especially in mathematics education. Mathematics teacher must aim the rationality of process where the mathematical belief is maintained. In fact, there is no problem in the rationality of content as long the mathematics teacher does not draw mathematical conclusions without bases. But, in the mathematical activities he presents in his class, mathematics teacher must be able to show hem together with what even his own belief on the efficiency and propriety of mathematical activites can be altered and advanced by a new thinking or new experiences.

• Journal of Dental Rehabilitation and Applied Science
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• 제29권1호
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• pp.45-58
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• 2013

The purpose of this study was to analyze the area of occlusal contact points using visual method. One subject was selected who had Angle Class I, normal dentition, without dental caries, periodontal disease and temporomandibular disorders. Forty times PVS impressions were taken and 10 pairs casts were fabricated using dental super hard stone. After mounting the casts with customized loading apparatus, 78.9kg/f force was loaded as a maximum biting force. In T-Scan method, occlusal contact points measurement was repeated twice. Then, using Photoshop program (Adobe photoshop CS3, Adobe. San Jose, USA), the pixels which indicated occlusal contact points by color was recognized, and the distribution of recognized pixels were calculated to area. In Add picture method, polyether bite material applied to the occlusal surface of the casts. Then, the image of the translucent areas was recorded and classified $0{\sim}10{\mu}m$, $0{\sim}30{\mu}m$, $0{\sim}60{\mu}m$ area by the amount of transmitted light. To acquire occlusal surface, the numbers of pixels from the photograph of the contact area indicated cast converted to $mm^2$. The mean occlusal contact area by two methods was statistically analyzed (paired t-test). Part of the red and pink area in T-Scan image were almost equivalent to the $0{\sim}10{\mu}m$, $0{\sim}30{\mu}m$, $0{\sim}60{\mu}m$ area in Add picture image. The distribution of occlusal contact points were similar, but the average area of occlusal contact points was wider in T-scan image (P<.05). Pink and red area in T-scan image was wider than $0{\sim}10{\mu}m$, $0{\sim}30{\mu}m$ area in Add picture image (P<.05), but similar to $0{\sim}60{\mu}m$area in Add picture image (P>.05). Occlusal contact points in T-scan image did not indicate real occlusal contact points. Occlusal contact areas in T-scan method were enlarged results comparing with those in Add picture method.

• Applied Chemistry for Engineering
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• 제7권5호
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• pp.877-887
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• 1996

The ideal membranes for membrane-covered oxygen probes system should be selectively permeable for oxygen and chemically inert, and have good mechanical strength. Polysulfone(PSf) was selected to develop the membrane for membrane-covered oxygen electrodes system. PSf membranes have properties such as good reproducibility, good mechanical strength, chemical inertness, and high heat resistance. PSf membranes were cast from polymer solution on the glass plate at constant temperature, and casting solvents used were tetrahydrofuran(THF), methylene chloride, and N-methyl-2-pyrrolidone(NMP). Tricresyl phosphate(TCP) as plasicizer was added to PSf to increase the softness of membrane. The permeation characteristics were observed for pure oxygen and nitrogen through pure PSf membranes by variable volume method and membrane-covered electrode system. The permeability coefficients of oxygen and nitrogen measured by variable volume method were slightly decreased with increasing of upstream pressure. The permeation properties of PSf membrane using methylene choride as casting solvent were not affected by the PSf amount of polymer solution. The permeability coefficients of oxygen and nitrogen for PSf membrane containing TCP were very slightly lower than those for pure PSf membrane, but ideal separation factors were slightly higher. The flexibility of PSf membrane containing 2wt% TCP was better than that of pure PSf membrane. It was expected that this increase in flexibility would solve the difficulty of fixing the membrane to the cathode. The membrane-covered oxygen probes system was composed of anode, cathode and electrolyte. The type of the anode was Ag/AgCl half-cell, that of cathode was Ag, and the electrolyte was 4N KCl solution. The result of sampled current voltametry for PSf membrane showed the plateu region at -0.3V~-1.0V. The correlation coefficient of oxygen partial pressure versus current for PSf membrane was relatively high, 0.99949. It was concluded that PSf membrane was the good candidate for the membrane-covered oxygen probes system.