• Applied Biological Chemistry
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• v.22 no.3
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• pp.135-141
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• 1979

These experiments were conducted to investigate the conditions of the acid protease production by Rhizopus oryzae and the characteristics of crude enzyme. The results obtained were as follows: 1. The optimum culture time and the optimum amount of added water to the wheat bran medium were about 48 hrs and $80{\sim}120%$, respectively. 2. The addition of $(NH_4)_6Mo_7O_{24},\;(NH_4)_2SO_4,\;NH_4NO_3$, casein, and albumin, respectively, as nitrogen sources to the wheat bran medium was effective. Of these, the optimum concentrations of addition of $(NH_4)_6Mo_7O_{24}$ and casein which were the most effective were 0.1% and 1.0%, respectively. 3. The addition of glucose, galactose, maltose, lactose, and soluble starch, respectively, as carbon sources to the wheat bran medium was effective. Of these, the optimum concentration of addition of glucose which was the most effective was 3.0%. 4. The addition of $KH_2PO_4$ as a phosphate salt to the wheat bran medium was effective. The optimum concentration of addition of $KH_2PO_4$ was 0.3%. 5. The optimum pH for the enzyme action was 2.4, the optimum temperature about $40^{\circ}C$, and the stable pH range $2.0{\sim}5.0$. The enzyme was stab1e below $40^{\circ}C$. 6. The enzyme activity increased rapidly for 10 minutes after addition, thereafter it increased slowly. 7. The enzyme activity increased rapidly to 2 ml of addition, but nearly did not increase at the amounts greater than 2ml.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.69-79
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• 2007

The purpose of this study was to investigate the effects of composite resin restorations on the stress distribution of notch shaped noncarious cervical lesion using three-dimensional (3D) finite element analysis (FEA). Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072 ; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). ANSYS (Swanson Analysis Systems, Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid or flowable resin and each restoration was simulated with adhesive layer thickness ($40{\mu}m$) A static load of 500 N was applied on a point load condition at buccal cusp (loading A) and palatal cusp (loading B). The principal stresses in the lesion apex (internal line angle of cavity) and middle vertical wall were analyzed using ANSYS. The results were as follows 1. Under loading A, compressive stress is created in the unrestored and restored cavity. Under loading B, tensile stress is created. And the peak stress concentration is seen at near mesial corner of the cavity under each load condition. 2. Compared to the unrestored cavity, the principal stresses at the cemeto-enamel junction (CEJ) and internal line angle of the cavity were more reduced in the restored cavity on both load con ditions. 3. In teeth restored with hybrid composite, the principal stresses at the CEJ and internal line angle of the cavity were more reduced than flowable resin.

• Journal of Korean Society of Forest Science
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• v.78 no.2
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• pp.177-188
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• 1989

The habitat typing method of classification based on community has been developed on many forested areas in the ROCKY MOUNTAINS of WESTERN NORTH AMERICA, and is being used in providing an objective principle of guide for classification of forest sites, land classification, vertical distribution and multipurpose management of forest. I actually made a trial of forest habitat type classification - The methodology can be segmented into a number of tasks including reconnaissance, selection of stands to be sampled, location of plots, data gathering, preliminary and computer analysis, preparation of key- and map of habitat type and description for each habitat type in a view of forest management - on UNIVERSITY OF MONTANA FORESTS in order to examine whether its application is fit or not in korean forest circumstances : these are composed mainly of artificial forest and forest in the early stage of succession. The main results obtained from this study were summarized as follows 1. A hierarchical classification-Climax, Habitat type and Phases-of forest sites was developed using the habitat typing method of classification. 2. A diagnostic key is provided for field identification of the types based upon presence and number of indicator species, and forest managers could prepare a map of habitat type and classify forest habirat types by reference to it. 3. The classified habitat types were considered to be effective on providing an objective principle of guide for multipurpose management of forest including potential productivity for timber, feed productivity of forage and wildlife, selection of the right species in the right sites, application of method of treatment and so forth. 4. Forest habitat type classifications based upon extrapolation which used relict species and associated stands is considered to be suitable for korean forest circumstances and objective in studying potential vegetation, vertical and horizontal distribution of forest.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.260-279
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• 2021

The Goguryeo kingdom established a unique defense system centered on a series of mountain fortresses. However, modern-day studies on its defense system have tended to focus on how they were positioned and generally consist of little more than individual surveys or introductions to the relevant materials, leaving much to be desired. This study attempts to extend the scope of studies about fortresses dating back to the Goguryeo period, taking into account the limitations of the available materials. As such, this study reviews the defense system of Goguryeo during the Gungnaeseong Period (i.e., the period when Gungnaeseong was the capital of Goguryeo) using the GIS system, with the focus on fortresses that are thought to have been built in the area extending from the middle and upper reaches of the Amnok River to the mid-stream region of the Liohe River, based on the aforementioned studies. The results of the study are as follows. First, the major roads built during the Gungnaeseong Period were as stated in the foregoing studies to some extent. Researchers believed that during the middle period of the dynasty, a major road ran along the Suzihe, Fuer and Xinkai rivers before finally reaching Jian. The study found that fortified walls and fortress strongholds were built along this road. Second, there were seven fortresses between the middle and upper reaches of the Amnokgang River and the midstream region of the Liaohe River. A primary defense line was closely established between the strongholds and the nearby walls, with secondary and tertiary defense lines established more loosely and encompassing a much wider area. Third, regarding the defense system along the major roads, the Choejinbosanseong, Goisanseong and Cheolbaesanseong fortresses served as strongholds along the 60-kilometer-long primary defense line, with 80-kilometer-long secondary and tertiary defense lines set up behind it. The final 120-kilometer-long defense line of the capital was established along with the Onyeosanseong Fortress, while a stumbling block was set up close to the capital as a defense system, rather than building a fortified wall. To summarize, a primary defense system was established centered on a series of fortresses, with each stronghold maintaining a closely-knit defense system in connection with other nearby strongholds to repel invaders.

• Journal of Korean Society of Forest Science
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• v.2 no.1
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• pp.59-65
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• 1962

The objects of this experiment are to find out the local variation of the Dendrolimus Spectabilis Butler, of which sample was first collecteted 15 bodies of male and 35 bodies of female adult at Suwon area. the wing veins and the scale shape have been observed through the microscope (100) and the scale size (from the bottom of the scale to the top of the lobe) has also been measured by the micrometer. The results of this experiment are as follows: 1. There is nodifference between the venation of the male body and that of the female body. Also we can not find any differences between the right and the left wing, and between each body. The fore wings consit of 13 longitudinal veins and the only one "V" shape cross vein which is between the 5th and 6th vein. The hind wings consist of 9 longitudinal veins and the only one "V" shape cross vein which is mentioned above. 2. The scale types are divided into 4 Groups in its shape. (A) The scales of I Group are short and the lower parts of them almost look like a circle, having a small projection at their bottom. The upper parts of them have 2 or 10 lobes. We can find the lobes with fine hairs or the lobes without them at the top of the scales. (B) The scales of II Group are longer than that of I Group. The shape of the lower parts of the scales is similar to that of I Group. The upper parts of the scales have 2 or 10 lobes. (C) The scales of III Group are long and almost alike in a long wedgeshape. The upper parts of the scales have 2 Or IO lobes and we can find long fine hairs at the top of each lobe. (D) The scales of IV Group are long and the shape of the lower parts of the scales is similar to that of III Group. The lobes are short and not sharp. We can find 2 or 9 lobes. 3. The scales of I Group and II Group are distributed on the whole surface except on the outer margin. The most scales of III Group are distributed on the wing base. The scales of IV Group are distributed on the outer margin only. The scales with 4 or 5 lobes are most widely distributed not considering their Group or distributing parts. 4. In I Group the variation of the scale length become gradually greater as the number of the lobes are increasing. In II, III, IV Group, however, the variation of the scale length is in direct opposition to the above mentioned. The variation of the scale width becomes pretty small in any Groups and the scale width become wider as the number of the lobes are increasing. 5. The source of the wing colouration is pigmnetal colour, and the wing colouration is expressed by the amount of brown and white scales.

• Journal of the Korean Wood Science and Technology
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• v.2 no.2
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• pp.5-7
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• 1974

1. This study indicates that above the fiber saturation point the drying rate can be increased with increasing the velocity of the air circutation, i.e., the drying rate of sample boards is proportional to the air velocity, but below the fiber saturation point, the effect of the velocity of air circulation is very low as shown in Figs. 1 and 2. 2. Under the controlled temperature and humidity in the kiln, the more the sample boards have moisture, the higher drying rate of it can be obtained. In other words, this means that even though in the case of drying various moisture content of wood, at the final drying stage, approximately the same percentage of moisture content of wood can be secured by employing the higher velocity of air circulation. 3. This study shows that the rate of drying in kiln changes distinctly at the fiber saturation point, i, e., above the fiber saturation point, the drying curve shows concave aginst the X axsis, but below the fiber saturation point, in the range from 30 percent of moisture content to 20 percent of moisture content, the curve shows convex as shown in Fig. 3. As the drying progresses, however, the drying curve shows concave again below 20 percent of moisture content. This means that inflection point of drying curve may be located clearly at the fiber saturation point, i.e., 30 percent of moisture content. As mentioned above, the 30 percent of moisture content of wood at which the inflectional point appears can be recognized as a critical point, i. e., the fiber saturation point at which all free water was removed from wood. The existence of inflectional point indicates that the evaporation of hygroscopic water in a cell wall is more difficult than the evaporation of free water in a cell cavity and the minor space of cell wall. The convex curve in the range of moisture content from 30 percent to 20 percent means that the evaporation of capillary condensed water has a tendency of the same rates of drying approximately, but as approaching to the 20 percent of moisture, the transfusion of moisture from wood becomes difficult because of having less moisture in cell wall. Below 20 percent of moisture content, the drying curve shows concave again, which means that it is difficult to remove the moisture located nearer to the surface of cellulose molecules and the surface bound water. These relations were revealed in Fig. 4. In comparison AC curve which does not have the two inflection points with BD curve which has two inflection points, i.e., Band D, they are mentioned already, by existence of the inflection points, the curve BD shows that the change of drying rate in the interval from 20 percent of moisture content to 30 percent of moisture content is not greater than in the case of the curve AC in the same interval. At the inflection point of 30 percent of moisture content, it can be noticed that the changing of the drying rate is very conspicuous. This phenomenon also can be recognized, as it is noticed by the Fig. 3, the drying rate from green to 30 percent of moisture content is very great. But the inclination of the curve is very slow from 30 percent of moisture content to 20 percent of moisture content, i.e., the inclination of the curve becomes almost horizontal lines. Acknowledgments Gratitude is expressed to Fred E. Dickinson, Professor of 'Wood Technology, School of Natural Resources, University of Michigan, USA for his suggestion to carry out this study.

• Journal of Korean Society of Forest Science
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• v.33 no.1
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• pp.33-58
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• 1977

A bark comprises about 10 to 20 percents of a typical log by volume, and is generally considered as an unwanted residue rather than a potentially valuable resourses. As the world has been confronted with decreasing forest resources, natural resources pressure dictate that a bark should be a raw material instead of a waste. The utilization of the largely wasted bark of genus Pinus, Quercus, and Populus grown in Korea can be enhanced by learning its physical and mechanical properties. However, the study of tree bark grown in Korea have never been undertaken. In the present paper, an investigative study is carried out on the bark of three genus, eleven species representing not only the major bark trees but major species currently grown in Korea. For each species 20 trees were selected, at Suweon and Kwang-neung areas, on the same basis of the diameter class at the proper harvesting age. One $200cm^2$ segment of bark was obtained from each tree at brest height. Physical properties of bark studied are: bark density, moisture content of green bark (inner-, outer-, and total-bark), fiber saturation point, hysteresis loop, shrinkage, water absorption, specific heat, heat of wetting, thermal conductivity, thermal diffusivity, heat of combustion, and differential thermal analysis. The mechanical properties are studied on bending and compression strength (radial, longitudinal, and tangential). The results may be summarized as follows: 1. The oven-dry specific gravities differ between wood and bark, further more even for a given bark sample, the difference is obersved between inner and outer bark. 2. The oven-dry specific gravity of bark is higher than that of wood. This fact is attributed to the anatomical structure whose characters are manifested by higher content of sieve fiber and sclereids. 3. Except Pinus koraiensis, the oven-dry specific gravity of inner bark is higher than that of outer bark, which results from higher shrinkage of inner bark. 4. The moisture content of bark increases with direct proportion to the composition ratio of sieve components and decreases with higher percent of sclerenchyma and periderm tissues. 5. The possibility of determining fiber saturation point is suggested by the measuring the heat of wetting. With the proposed method, the fiber saturation point of Pinus densiflora lies between 26 and 28%, that of Quercus accutissima ranges from 24 to 28%. These results need be further examined by other methods. 6. Contrary to the behavior of wood, the bark shrinkage is the highest in radial direction and the lowest in longitudinal direction. Quercus serrata and Q. variabilis do not fall in this category. 7. Bark shows the same specific heat as wood, but the heat of wetting of bark is higher than that of wood. In heat conductivity, bark is lower than wood. From the measures of oven-dry specific gravity (${\rho}d$) and moisture fraction specific gravity (${\rho}m$) is devised the following regression equation upon which heat conductivity can be calculated. The calculated heat conductivity of bark is between $0.8{\times}10^{-4}$ and $1.6{\times}10^{-4}cal/cm-sec-deg$. $$K=4.631+11.408{\rho}d+7.628{\rho}m$$ 8. The bark heat diffusivity varies from $8.03{\times}10^{-4}$ to $4.46{\times}10^{-4}cm^2/sec$. From differential thermal analysis, wood shows a higher thermogram than bark under ignition point, but the tendency is reversed above ignition point. 9. The modulus of rupture for static bending strength of bark is proportional to the density of bark which in turn gives the following regression equation. M=243.78X-12.02 The compressive strength of bark is the highest in radial direction, contrary to the behavior of wood, and the compressive strength of longitudinal direction follows the tangential one in decreasing order.