• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.142-147
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• 2005

The embrittlement of fast neutron-irradiated reactor pressure vessel (RPV) steels was investigated by X-ray diffraction patterns at room temperature and $M\ddot{o}ssbauer$ spectroscopy at room- and liquid nitrogen-temperature. Neutron fluence on the samples were $10^{12},\;10^{13},\;10^{14},\;10^{15},\;10^{16},\;10^{17},\;10^{18}\;n/cm^2$. The X-ray diffraction patterns showed that the structure of the neutron unirradiated sample was bcc type, where as but the neutron irradiated samples with the fluence higher than $10^{17}\;n/{\cal}cm^2$ were so severely damaged, that bcc type structure disappeared. The $M\ddot{o}ssbauer$ spectra of all samples showed superposition of two or more sextets. In this paper all $M\ddot{o}ssbauer$ spectra were fitted by three set of sextet. The isomer shift and quadrupole splitting values were found around zero. At liquid nitrogen temperature, magnetic hyperfine field and absorption area increase rapidly S 1 sextet in the samples of $10^{17}\~10^{18}\;n/{\cal}cm^2$ neutron fluences. And at room temperature, magnetic hyperfine field and absorption increased rapidly at SI sextet in the samples of $10^{17}\~10^{18}\;n/{\cal}cm^2$ neutron fluences. This rapid increase of magnetic hyperfine field and absorption area were inferred to be caused by the change of $^{56}Fe,\;^{55}Mn$ into $^{57}Fe$ due to by neutron irradiation.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.429-444
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• 1988

Considering the recent trent toward the development of multiple-use of forest trees, investigations for comprehensive information on these young stands of Hinoki cypress are necessary for rational forest management. From this point of view, 83 sample trees were selected and cut down from 23-ear old stands of Hinoki cypress at Changsung-gun, Chonnam-do. Various stem growth factors of felled trees were measured and canonical correlaton analysis, principal component analysis and factor analysis were applied to investigate the stem growth characteristics, relationships among stem growth factors, and to get potential information and comprehensive information. The results are as follows ; Canonical correlation coefficient between stem volume and quality growth factor was 0.9877. Coefficient of canonical variates showed that DBH among diameter growth factors and height among height growth factors had important effects on stem volume. From the analysis of relationship between stem-volume and canonical variates, which were linearly combined DBH with height as one set, DBH had greater influence on volume growth than height. The 1st-2nd principal components here adopted to fit the effective value of 85% from the pincipal component analysis for 12 stem growth factors. The result showed that the 1st-2nd principal component had cumulative contribution rate of 88.10%. The 1st and the 2nd principal components were interpreted as "size factor" and "shape factor", respectively. From summed proportion of the efficient principal component fur each variate, information of variates except crown diameter, clear length and form height explained more than 87%. Two common factors were set by the eigen value obtained from SMC (squared multiple correlation) of diagonal elements of canonical matrix. There were 2 latent factors, $f_1$ and $f_2$. The former way interpreted as nature of diameter growth system. In inherent phenomenon of 12 growth factor, communalities except clear length and crown diameter had great explanatory poorer of 78.62-98.30%. Eighty three sample trees could he classified into 5 stem types as follows ; medium type within a radius of ${\pm}1$ standard deviation of factor scores, uniformity type in diameter and height growth in the 1st quadrant, slim type in the 2nd quadrant, dwarfish type in the 3rd quadrant, and fall-holed type in the 4 th quadrant.

• Proceedings of the KOR-KST Conference
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• 1996.02a
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• pp.59-86
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• 1996

Current methods for evaluating unsignalized intersections, and estimating level-of-service (LOS) is determined from efficiency-based criteria such as little or no delay to very long delays. At present, similar procedures to evaluate intersections using safety-based criteria do not exist. The improvement of sight distances at intersections is the most effective way of improving intersection safety. However, a set of procedures is necessary to account for the limitations in current methodology. Such an approach would build upon such methods, but also account for: deficiencies in the current deterministic solution for the determination of intersection sight distances; opportunity for an accident and severity of an accident; and cost-effectiveness of attaining various levels of sight distances. In this research, a model that estimates the degree of safety at two-way stop-controlled intersections is described. Only crossing maneuvers are considered in this study because accidents caused by the crossing maneuvers are the dominate type among intersection accidents. Monte Carlo methods are used to estimate the hazard at an intersection as a function of roadway features and traffic conditions. Driver`s minimum gap acceptance in the crossing vehicles and headway distribution on the major road are used in the crossing vehicles and headway distribution on the major road are used in the model to simulate the real intersectional maneuvers. Other random variables addressed in the model are: traffic speeds; preception-reaction times of both drivers in the crossing vehicles and drivers in oncoming vehicles on the major road; and vehicles on the major roads. The developed model produces the total number of conflicts per year per vehicle and total potential kinetic energy per year per vehicle dissipated during conflicts as measurements of safety at intersections. Based on the results from the developed simulation model, desirable sight distances for various speeds were determined as 350 feet, 450 feet and 550 feet for 40 mph, 50 mph and 60 mph prevailing speed on the major road, respectively. These values are seven to eight percent less than those values recommended by AASHTO. A safety based level-of-service (LOS) is also developed using the results of the simulation model. When the total number of conflicts per vehicle is less than 0.05 at an intersection, the LOS of the intersection is `A' and when the total number of conflicts per vehicle is larger than 0.25 at an intersection, the LOS is `F'. Similarly, when the total hazard per vehicle is less than 350, 000 1b-ft2/sec2, the LOS is `F'. Once evaluation of the current safety at the intersection is complete, a sensitivity analysis can be done by changing one or more input parameters. This will estimate the benefit in terms of time and budget of hazard reduction based upon improving geometric and traffic characteristics at the intersection. This method will also enable traffic engineers in local governments to generate a priority list of intersection improvement projects.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.163-171
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• 2001

It is important to pay careful attention to the backfill construction for the structural integrity of concrete box culvert. To increase the structural integrity of culvert good compaction by the dynamic compaction roller with big capacity is as effective as good backfill materials. However structural distress of the culvert could be occurred due to the excessive earth pressure by great dynamic compaction load. In this study, two box culverts were constructed with change compaction materials and construction methods. Two type of on-site soils such as subbase and subgrade materials were used as backfill materials. In most case, dynamic compaction rollers with 11 to 12 ton weights were used and vibration frequency were applied from 2000 to 2500 rpm for the great compaction energy. Backfill compactions with good quality soils were carried out to examine the effect of cushions on dynamic lateral soil pressure. Expanded polystyrene (EPS) and rubber of tire were adapted as cushion materials and they are set on the culverts before backfill construction. This paper presents the main results on the characteristics of dynamic earth pressures. Test result indicates that the amounts of increased dynamic pressures are affected with backfill materials, depth of pressure cell, and compaction condition. The earth pressure during compaction can give harmful effect to box culvert because the value of dynamic earth pressure coefficient $(\DeltaK_{dyn}=\DeltaK\sigma_h\DeltaK\sigma_v)$ during compaction is greater than that of static condition. It was observed that cushion panels of EPS(t=10cm) and rubber(t=5cm) are effective to mitigate dynamic lateral pressure on the culverts.

• Applied Biological Chemistry
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• v.28 no.1
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• pp.19-27
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• 1985

The physicochemical properties of starch isolated from Yullmoo (Coix lachrymajobi var. mayuen stapf.) and Yeomjoo (Coix lachryma-jobi L.) were investigated. The average diameters of starch granules of Yullmoo and Yeomjoo were 12.0 microns, both of all, and the shape of these starch granules were hexagon, octagon and round. X-ray diffraction patterns of two samples were A-types and amylose contents of Yullmoo and Yeomjoo starch were 0% and 23%, respectively, iodine affinities of these were 0.08% and 4.2%, respectively, blue values and alkali numbers of these were 0.13 and 0.43, 2.4 and 7.2, and raising power of these were 280 and 20, respectively. Yullmoo starch had higher swelling power than Yeomjoo starch. The increase in optical transmittance of 0.1% suspensions of Yullmoo and Yeomjoo starches occurred at $60^{\circ}C$ and continued up to $75^{\circ}C$ for Yullmoo, $85^{\circ}C$ for Yeomjoo. Amylogram data on 5% of Yullmoo and Yeomjoo starch suspensions showed that gelatinization temperatures and maximum peak heights of Yullmoo and Yeomjoo were $68.5^{\circ}C\;and\;78^{\circ}C$, 920 and 310 B.U., respectiyely. Intrinsic viscosities of Yullmoo and Yeomjoo starches were 1.49 and 1.77, respectively, and interaction coefficients of the two starches were 0.57 and 0.56, respectively The extent of retrogradation determined at $2^{\circ}C$ showed that retrogradation occurred slowly with Yullmoo starch paste tut little with Yullmoo.

• Journal of Aquaculture
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• v.11 no.1
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• pp.99-103
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• 1998

Artemia often observed as a co-existing organism in the mass culture tank of marine rotifer. The rotifer and Atremia are commonly used as food organisms in the marine fish larvae rearing. In this study, interspecific relation between the rotifer Brachionus rotundiformis (formely called S-type) and anostracan Artemia of the two developmental stages (0 and 19 day old after hatching) were investigated in the larboratory. The population growth of B. rotundiformis and one of the stage (nauplius or adult) of Artemia in mixed culture was compared with that of each single species culture. Culture period was 16 days. Every two days, the number of organisms in each species was counted and transferred to a fresh medium containing $7{\times}10^5$cells/ml of food Nannochloropsis oculata. Culture volume, temperature, salinity and photoperiod were set at 40ml, $25^{\circ}C.$, 22ppt and 24h all dark except to observation time, respectively. The rotifer population growth was greatly decreased by co-existence with Artemia. The coexisting Artemia suppressed the rotifer population growth due to it's high filtering speed for food (N. oculata). This study suggested that contamination by Artemia must be prevented for the stable rotifer production in the rotifer mass culture tank.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.199-208
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• 2002

This paper introduces the method to make management network about milking cow farm tasks. The object of this research was to design of biological measuring system and managing network system in a livestock farm. This auto-management system provides informations about individual cows' temperature, conductivity of milk and weight for efficient management of feeding, and milking works by a micro-processor and RS -485 type serial COM. ports. And measured bio-data which are basic informations for remote raising management are saved to user PC by serial communication between the PLC and user PC. Milking cow farm is divided into three working place to each measurement work and feed. The first working place is milking station which has two thermometers, a conduct meter and a scale set. The second working place is feeding station, and the third place is cattle cage. These are combined by network system and the PLC which is used to drive network and sub-modules. Sub-modules have a micro-process to control the sensor and to interface with network. The PLC which drive network and control sequence has two serial communication port to be linked with user PC for sending the measured data and for receiving data. Above all, in this study tells the sequence operating method by the driving scenario of breeding milk cow for livestock auto-management using the PLC and network system.

• Korean Journal of Cognitive Science
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• v.13 no.2
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• pp.1-13
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• 2002

This Paper is concerned with the impact of linguistic markers of coherence, such as causal connectives. repetitions. and anchoring devices. on the comprehension of a scientific text in Korean. A scientific text on the process of lightning formation was selected. and two versions of the text were constructed by varying the strength of coherence. Eighty-two undergraduate students took Part in the experiment in which they were instructed to fill in the blanks in each text in a recall and a recognition task and to respond to a set of question in a comprehension test. The results of this experiment revealed a selective effect of the cohesive markers. It was found that the different linguistic signals seem to Play a facilitating role in varying degrees in accordance with the type of tasks involved Moreover an analysis of topic continuity from the beginning paragraphs through the last revealed that the text was better understood in the paragraphs containing the main topic better than those without it. This finding seems to indicate that the off-line processing of scientific text is not influenced solely by the local bottom-up processing alone The effect of topic continuity seems to suggest that a global. top-down processing effect has an important role to play. overriding the impact of cohesive devices.

• Journal of Korean Academy of Nursing
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• v.27 no.2
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• pp.444-453
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• 1997

The purpose of this study was to construct a grounded theory as the basis for nursing intervention by describing and analysing the holistic lived experiences of clients receiving long-term hemodialysis. The subjects of this study were fifteen persons receiving regular hemodialysis regimen at artificial kindey treatment centers in two different university hospitals, and who were able to participate in conversation and were available for long and dup interviews. Eight of the subjects were male and seven were female and their ages ranged from 30's to 60's. The length of the hemodialysis experience ranged from two months to six years. The collection and analysis of data were done in accordance with the grounded theory methodology of Strauss & Corbin. The method to collect the data mainly depended. on long and deep interviews, participant observation and focused group interviews and the equipment used to collect data were a portable tape recorder and field notes. The study is summarized as follows : 1. The meaning of holistic lived experiences of clients receiving long -term hemodialysis was found to be uncertainty. which was identified as the core category. 2. The main categories following the core category were found to be shock, ambiguity, social support and quality of life. 3. Through the main category the type of behavior newly formed by clients receiving long-term hemodialysis was found to be as follows. That is to say, in the circumstances of shock caused by the identified fact and the ambiguity of hemodilysis they formed a quality of life based on social support, which was found to be a kind of chaotic phenomenon. 4. The lived experiences of clients receiving long-tern hemodialysis was found to include nine categories : emotional shock, feelings of isolation, burden, unclearness, dependency, help from others, coping strategies, maintenance of self-esteem and transitional life. 5. The intervening factors influencing each category are as follows : 1) The factors influencing 'emetional shock' were found to be set age, the level of knowledge received in advance, locus of control, the period of struggle against the disease before hemodialysis and whether any serious illness existed. 2) The factors influencing 'feelings of isolation' were found to be religion and the length of the hemodialysis experience. 3) The factors influencing 'burden' were found to be sex, economic situation, employment status and the length of the hemodialysis experience. 4) The factors influencing 'unclearness' were found to be sex, age, religion. economic situation, the length of the hemodiaysis experience, whether they had had a transfusion and whether there were any complications. 5) The factors influencing 'help from others' were found to be religion. economic situation, past experiences and whether family members lived together. 6) The factors influencing 'coping strategies' were foung to be age, level of education, experiences of illness and locus of control. 7) The factors influeruing 'maintenance of self-esteem' were found to be the length of the hemodialysis experience and self-actualization. 8) The factors influencing 'transitional life' were found to be age, religion, economic situation, employment status. locus of control. past experiences and whether there was a plan for a kidney transplant.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.86-94
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• 2000

In order to extract the spatio-temporal characteristics of long-term variability of the net heat flux on the sea surface in the East Asian marginal seas, empirical orthogonal function (EOF) analysis was conducted using data set calculated every 12 hours interval during 1978-1995. Among the first three modes explaining 73% of the total variance, the first mode having high peak at 1 year period indicates high variability area around the Sandong Peninsula and central and northeastern part of the East Sea. In the second mode which has spatial distribution of dipole type at the north and south, the peaks appear at 3.6 year and 2.3 year cycles. Time coefficient of the second EOF is believed to have close relation with the E1 Nino and has out-of-phase variation with NINO3 SST. Lagged correlation between NINO3 SST and time coefficient of the second EOF indicates four month time delay in the NINO3 SST. In the third mode which has opposite sign at the east and west, the periodicity of 6-9 year cycle has relatively clear appearance compared to other two EOFs. Also, high heat loss exceeding 800 W/$m^{2}$ in winter time occured at the south part of the Sandong Peninsula and Vladivostok. It reveals more frequent occurrence of about two times at the Sandong Peninsula than Vladivostok. The event is concentrated in January at Vladivostok, but it occurs primarily in December and January at the Sandong Peninsula.