• Journal of the Korean School Mathematics Society
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• v.4 no.1
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• pp.103-114
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• 2001

The purpose of this study is to develop learning materials for functional concept on variable and to verify the effect of how well students could learn functional concept after they studied with those materials. To accomplish the purpose of this study, I developed learning materials and after teaching students with them. I have concluded the followings : First, there was little effect in teaching functional concept on variable between two experimental groups, whereas teaching functional concept had greater effect on forming functional concept in high level groups in those two experimental groups. Second, teaching functional concept on variable had little effect on students' understanding of functional concept and perfecting tables in Black box, graph, and mathematical problems, whereas there was much effect in students' understanding functional concept and solving relation formula, image, and range problems related to everyday life or general things. On the basis of the problems which appeared in the process of this study, the following can be suggested : First, we should develop learning materials fit for low level students so that they could understand functional concept. Second, we should continue to teach the basic problems like solving relation formula, image, and range, and understanding functional concept in graph until students are able to understand them exactly. Third, since the goals of Unit Function in a middle school textbook is to solve problems related to everyday life through functional thinking, there should be change in constructing systematic contents of Unit Function in a middle school textbook.

• Science of Emotion and Sensibility
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• v.13 no.2
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• pp.337-346
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• 2010

The purposes of this research were to evaluate the color sensibility and preferences, and to analyze the effect of the tactile preferences and purchasing preference on structural properties, color characteristics and color sensibility for the black color fabrics. Male and female university students were asked to evaluate the color sensibility, tactile preference and purchasing preference to the nine different black fabrics which were selected on the basis of the previous research results. Data were analyzed by using frequency analysis, mean, factor analysis, t-test, Kruskal-Wallis test, correlation and regression analysis. The color sensibility for black color fabrics was classified into four factors: simplicity/classic, elegance, modernity and dignity. This color sensibility factors showed a significant correlative relationship to the structural properties and color characteristics of black color fabrics. On the other hand, fabrics which were evaluated with good tactile preference among the black color fabrics tended to show higher purchasing preference. Also, among the color sensibility, the structural properties and color characteristics of black color fabrics, major variable factor of influencing on the tactile preference and the purchasing preference was turned out to be the color sensibility.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.4
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• pp.241-247
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• 1991

Electric charge characteristics of volcanic ash soils in Cheju Island were investigated. For this study, soils of toposequence distributed along the sourthern slope of Mt. Halla, and the major soil groups such as dark brown soils, very dark brown soils, black soils, and brown forest soils were collected and analyzed for extratable acidity, KCl ext. Al, CEC, base saturation, permanent charge and variable charge, etc.. Weolpyeong and Yongheung soils developed on the lower elevations have high $NH_4OAc$ ext. bases, permanent charge and base saturation, and relatively low ext. acidity, CEC and variable charge. For other soils, whose colloidal fractions are dominated by allophane or Al-humus complexes, ext. acidity, CEC, variable charge, and variable charge ratio were very high, and $NH_4OAc$ ext. bases, permanent charge, and base saturation were very low. These trends were especially prominant in the surface. horizons of black soils and brown forest soils dominated by Al-humus complexes. Ext. acidity, CEC($NH_4OAc$), CEC(sum of cations), and variable charge strongly correlated with pyrophosphate ext. carbon. Very dark brown soils and cinder cone soils dominated by allophane showed low KCl ext. Al and relatively high pH, despite their very low base saturation.

• The Research Journal of the Costume Culture
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• v.12 no.6 s.53
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• pp.971-983
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• 2004

The purpose of this study was to investigate the effect of perceiver's social value, hair style, and hair color of object person on image perceptions. For social value variable, materialism and traditionalism were investigated. Subjects were 343 women in Seoul. Perceiver's materialism gave a significant influence on perception of elegance. The less materialistic group evaluated the hair style of object person more elegant than the more materialistic group. The more traditional group evaluated bright brown hairs less pretty than the less traditional group. This means that traditional people have less preferable image on bright brown hairs compared to the black and dark brown hair as it is different from Korean traditional hair color. Medium straight hair styles were evaluated lowest in preference and individuality. Short straight hairs were evaluated as the most elegant style and medium permanent hairs as the least elegant one. Long wavy hairs were evaluated highest in femininity, and straight hairs were evaluated lower in prettiness and activity than wavy hairs. The bright brown hairs were evaluated as the most individual color, and black was the least one. The bright brown was perceived lowest in elegance. Black and dark brown of the short straight hair style were perceived much more elegant than the bright brown of the same style, and black long wavy hairs were evaluated highest in femininity. The present findings provide that social value, hair style, and hair color are significant characteristics when perceiving women's image.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.553-566
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• 1997

Origin, behavior and enrichment of environmental toxic elements from the Deokpyeong area were investigated on the basis of major, trace and rare earth element geochemistry. Coaly metapelites of the Deokpyeong area are subdivided into grey phyllite, dark grey phyllite, coaly slate and black slate, which are interbedded along the Ogcheon Supergroup. The coaly slate had been mined for coal, but mining is closed. The coaly and black slates are lower contents of $SiO_2$ and $Al_2O_3$, and higher contents of LOI, CaO, $Na_2O$ and BaO as compared with the phyllitic rocks. Rare earth elements are highly enriched in the coaly and black slate. Average compositions (ppm) of minor and/or environmental toxic elements in the coaly and black slate are revealed as As=127, Ba=30,163, Cd=18, Cr=740, Cu=84, Mo=378, Pb=43, Sb=12, Se=44, U=144, V=8,147 and Zn=292, which are extremely high concentrations than those in the NASC compositions. Major elements (average enrichment index; 5.34) in the coaly metapelites are mostly depleted, excepting $P_2O_5$ and BaO, normalized by NASC. Rare earth elements (average enrichment index; 1.48) are enriched in the coaly slate. On the basis of NASC, minor and/or environmental toxic elements in the coaly metapelites were strongly enriched of all the elements with the exception of Co, Cs, Ni and Sr. Average enrichment index of trace elements in coaly metapelite is 31.51 (coaly slate; 51.94 and black slate; 15.46). Especially, enrichment index of potentially toxic elements (As, Ba, Cr, Cu, Mo, Ni, Sb, Se, U, V and Zn) of the rock is 46.10 (grey phyllite; 7.15, dark grey phyllite; 4.77, coaly slate; 88.96 and black slate; 22.11). These coal formations were deposited in basin of boundary between terrestrial and marine environments deduced to carbon, sulfur (C/S=2.2 to 275.7), trace and rare earth elements characteristics. Irregular behavior and dispersion between major, minor and rare earth elements of those metapelites indicates a variable source materials, incomplete mixing of differential source and/or reequilibrium of diagenesis and metamorphism.

• Mycobiology
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• v.29 no.2
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• pp.110-112
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• 2001

A black scab was observed on strawberry(Fragaria ananassa) in plastic film houses around Jinju area during the winter of 2000. The disease started from leaves then moved to calyx and runner. At the beginning, the infected area started with small dark brown spots then gradually expanded. The pathogenic fungus was purely isolated from the diseased leaves, calyx and runner. The fungus was inoculated to test Koch's postulates and proved to be the causal agent of the disease. The isolated fungus grew readily on potato dextrose agar, forming dark green to dark gray colonies. The optimum temperature for mycelial growth was about $25^{\circ}C$. The diameter of growing hyphae was $3.8{\sim}5.6{\mu}m$. Conidia were ellipsoidal, ovoid or subspherical, mostly one-celled but occasionally septate. The size of conidia were $4.1{\sim}11.7{\times}3.8{\sim}5.3$ 1-cell, $9.3{\sim}18.8{\times}4.0{\sim}7.4{\mu}m$ 2-cell and formed in long branched chains on the erected conidiophores which were dark brown and variable in length between $28.8{\sim}236.2{\times}3.0{\sim}6.2{\mu}m$ in size. The fungus was identified as Cladosporium herbarum on the basis of its morphological characteristics. The black scab disease of strawberry caused by C. herbarum has not been reported in Korea previously.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.1
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• pp.1-21
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• 2015

This paper presents two algorithms based on the Jamshidian equation which is from the Black-Scholes partial differential equation. The first algorithm is for American call options and the second one is for American put options. They compute numerically free boundary and then option price, iteratively, because the free boundary and the option price are coupled implicitly. By the upwind finite-difference scheme, we discretize the Jamshidian equation with respect to asset variable s and set up a linear system whose solution is an approximation to the option value. Using the property that the coefficient matrix of this linear system is an M-matrix, we prove several theorems in order to formulate a bisection method, which generates a sequence of intervals converging to the fixed interval containing the free boundary value with error bound h. These algorithms have the accuracy of O(k + h), where k and h are step sizes of variables t and s, respectively. We prove that they are unconditionally stable. We applied our algorithms for a series of numerical experiments and compared them with other algorithms. Our algorithms are efficient and applicable to options with such constraints as r > d, $r{\leq}d$, long-time or short-time maturity T.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.1
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• pp.25-31
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• 2001

The titanium miniplate osteosynthesis system has been used for fixation of bone fragments in the maxillofacial areas due to easy manipulation and even has been proposed for unnecessity of miniplate removal because of the biocompatibility and the corrosion resistance. But recently, there have been some suggestions for its removal, on the basis of findings that there have been pigmentations around the adjacent tissues during miniplate removal procedure and they are the depositions of metal particles. Purposes of this study are to ascertain the presence and nature of pigmentation observed within tissues adjacent to titanium miniplate, and to suggest possible causes of it. We could observe the black pigmentation during miniplate removal procedure for recent about 1.5 year. Pigmented tissues were stained with hematoxylin-eosin(H-E) for light microscophic(LM) examination to investigate the black pigmentations and the histomorphology around them. The scanning electron microscopy(SEM) with energy dispersive X-ray(EDX) analysis was used to examine the ultrastructural nature of pigmentations. Many metal particles with variable sizes and shapes were seen in the connective tissue by SEM and were identified as titanium by EDX.

• The Plant Pathology Journal
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• v.19 no.4
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• pp.200-202
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• 2003

Leaf spots were first observed on watermelon (Citrullus vulgaris Schrad) under polyethylene film-covered green-house in November 2002. Symptoms appeared as dark-brown circles or large irregular spots on the leaves of watermelon. Occasionally, zonal growth of the lesions was observed. Under humid conditions, small black sclerotium-like bodies (sporodochia) were produced on the surface of the lesions. The sporodochia on leaf lesions were sessile, polymorphic, variable in size, 35-850 $\mu\textrm{m}$ in diameter, and 30-470 $\mu\textrm{m}$ in depth. Conidia in sporodochium were black in mass, one-celled, rod-shaped, with rounded ends, hyaline, guttulate, and measured 6-8$\times$1.6-2.2 $\mu\textrm{m}$ in size. The pathogen was identified as Myrothecium roridum Tode ex Fr. This is the first report of Myrothecium leaf spot on watermelon naturally occurring in commercial greenhouses.

• Journal of the Korean Society of Costume
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• v.47
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• pp.33-46
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• 1999

The purpose of this study is to investigate the Aksu(握手) a kind of shroud This study classifies Aksu by its size shape cloths and color. Korean Aksu through literatures are as follows: The length of Aksu was one Ch'ok(尺) two Ch'on(寸) and the width of Aksu was five Ch'on. The surface pf Alsi were mostly black and the liniing was mostly red. The cloths of Aksu were Paek(帛) and Chu(紬). Aksu through relics was various in size and the cloths were Kongdan(貢緞) Myongchu(明紬) and Sa(紗) and the color was various. Actual conditions of current Aksu were various. The size shape cloths and color were more variable than the literatures and relics. The band of Aksu was all two. n the Chinese Aksu through literatures the length was one Ch'ok two Ch'on and the width waf five Ch'on The cloths of Aksu were Paek and Kyon. The surface of Aksu were mostly black and the lining was mostly red. Aksu in Munkonggaryoieuichul(文公家禮儀節) was tide by the strings of four corners. The Size of the Korean Aksu was the same as Chinese Aksu. The shape of the current Aksu was various than the literatures and relics.