• Journal of Forest and Environmental Science
• /
• v.28 no.4
• /
• pp.205-211
• /
• 2012

Yield tables are a frequently used data base for regional timber resource forecasting. A normal yield table is based on two independent variables, age and site (species constant), and applies to fully stocked (or normal) stands while empirical yield tables are based on average rather than fully stocked stands. Normal and empirical yield tables essentially have many limitations. The limitations of normal and empirical yield tables led to the development of variable density yield tables. Mathematical models for estimating timber yields are usually developed by fitting a suitable equation to observed data. The model is then used to predict yields for conditions resembling those of the original data set. It may be accurate for the specific conditions, but of unproven accuracy or even entirely useless in other circumstances. Thus, these models tend to be specific rather than general and require validation before applying to other areas. Dalbergia sissoo forms a major portion of irrigated plantations in the hot desert of India and is an important timber tree species where stem wood is primarily used as timber. Variable density yield model is not available for this species which is very crucial in long-term planning for managing the plantations on a sustained basis. Thus, the objective of this study was to develop variable density yield model based on the data collected from 30 sample plots of D. sissoo laid out in IGNP area of Rajasthan State (India) and measured annually for 5 years. The best approximating model was selected based on the fit statistics among the models tested in the study. The model develop was evaluated based on quantitative and qualitative statistical criteria which showed that the model is statistically sound in prediction. The model can be safely applied on D. sissooo plantations in the study area or areas having similar conditions.

• Journal of the Korea Society for Simulation
• /
• v.28 no.4
• /
• pp.1-10
• /
• 2019

The Sea Water Reverse Osmosis (SWRO) plant should take into account the availability of the plant from the design stage for long-term and continuous fresh water production. As it occurs, it is necessary to establish a corrective maintenance plan and preventive maintenance plan to maintain availability. In the field of complex engineering structures such as seawater desalination plants, it is difficult to estimate the reliability or availability of the system in a mathematical way. This study develops RAM analysis framework and model, and proposes discrete event simulation model as a application sowtware specialized for seawater desalination plant. Considering the characteristics of the plant maintenance, in case of corrective maintenance, we propose a preventive maintenance policy that not only repairs or replaces a single-broken part, but also simultaneously maintains all accessible parts according to the level of overhaul. A case study was conducted to estimate the availability of the system based on the field data of the seawater desalination plant in Korea and Saudi Arabia. The result was close to the expected availability of the plant.

• Journal of Elementary Mathematics Education in Korea
• /
• v.15 no.2
• /
• pp.301-316
• /
• 2011

In this study, some discordance between curriculum and textbooks in usage of mathematics terms, dual meaning of some terms in the usage of those terms in textbooks, and inconsistency of defining methods of terms are discussed through some examples. Generally it can not be expected that there are any discordance between curriculum and textbooks, because textbooks are developed in the basis of curriculum. But actually, some discordance between curriculum and textbooks can be found out. Some terms are used with two different meaning, geometric figure and measure. It can be causative of troubles in teaching and learning mathematics. Terms of same kind can be expected to be consistent in the way of defining, but some examples defined inconsistently can be found out. The following four suggestions are offered as conclusions. First, textbooks must be consistent with curriculum. Second, The meaning of terms used in textbooks must be stipulated obviously. Third, terms of same kind must be defined consistently. Fourth, it is necessary to supplement a system for developing elementary mathematics textbooks. The result of this study can help develop new textbooks, and revise curriculum, and develop new curriculum.

• The Korean Journal of Applied Statistics
• /
• v.33 no.4
• /
• pp.421-437
• /
• 2020

This paper implemented a method to predict the fertility rate, mortality rate, and international migration rate using the R program, which has been widely used in recent years, that calculates population projection by substituting the results into the Leslie matrix. In particular, the generalization log gamma model for the fertility rate by Kaneko (2003), LC-ER model for mortality rate by Li et al. (2013), and functional data model for international migration rates proposed by Ramsay and Silverman (2005) and Hyndman and Booth (2008), Hyndman et al. (2013) can be directly demonstrated with R programs. Demography and bayesPop have been introduced as a representative demographic package implemented in R; however, it can be analyzed only for data uploaded to Human Mortality Database (HMD) and Human Fertility Database (HFD) with data changes and modifications requiring application of other data. In particular, in Korea, there is a limitation in applying this package because it is provided only for short-term data in HMD. This paper introduces an R program that can reflect this situation and the different patterns of low fertility, aging, migration of domestic and foreigners in Korea, and derives a population projection for the year 2117.

• Journal of architectural history
• /
• v.12 no.4 s.36
• /
• pp.49-62
• /
• 2003

Vesely explains, the main source of our confusion and nihilism comes most probably from the ambiguous relationship between modem architecture, technology and aesthetics. Also, to overcome such crucial problems, many theorists recently emphasize to take part in cultural civilization and to preserve creative genes of great culture that is based on our interpretation of 'ethical and mythical nucleus of mankind,' rather than in technical modernization that constitutes a sort of subtle destruction of mytho-ethical nucleus of a society. They for architecture also strongly stress on a mythopoetic imagination and an ontological construction of building, which could make a form symbolic and mythical rather than mathematical and aesthetic representation. On this point, 'myth' becomes a vital idea for constructing and construing architectural form and space. And it is also one of the essential concepts to understand both the motive power of cultural continuation of place and the meaning of architecture. Nevertheless, its meaning and the citation of word in architectural essay are still obscure. It might be because the original concept of myth not only has been lain in the matter of philosophical contemplation. Thus, the intention of the research is focused on lightening the meaning of myth in architectural term. Especially, it is, first, concentrated on interpreting philosopher Ernst Cassirer's reflections which were written in order to emphasize the importance of 'mythical consciousness' for the world's cultural civilization. And, the second, it will continue to interpret the myth as a sign within the semiotic concept of Charles Sanders Peirce, and further to emphasis the significance of mythic signs for the continuance of artistic and cultural idea including architecture. The contents of the paper is not that of architectural planning and design methodology, rather architectural philosophy and epistemology. Nevertheless, in regard to architecture, the research will, against today's un-discriminated use of symbolic motifs and instrumental representation of form, suggest a concrete architectural and aesthetic theory of myth and sign, especially of the relationship between the idea of semiology and the function of cultural continuity.

• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.4
• /
• pp.295-301
• /
• 2013

Long-term global energy-demand growth is expected to increase driven by strong energy-demand growth from developing countries. Fusion power offers the prospect of an almost inexhaustible source of energy for future generations, even though it also presents so far insurmountable scientific and engineering challenges. One of the challenges is safe handling of hydrogen isotopes. Metal hydrides such as depleted uranium hydride or ZrCo hydride are used as a storage medium for hydrogen isotopes reversibly. The metal hydrides bind with hydrogen very strongly. In this paper, we carried out a modeling and simulation work for absorption/desorption of hydrogen by ZrCo in a horizontal annulus cylinder bed. A comprehensive mathematical description of a metal hydride hydrogen storage vessel was developed. This model was calibrated against experimental data obtained from our experimental system containing ZrCo metal hydride. The model was capable of predicting the performance of the bed for not only both the storage and delivery processes but also heat transfer operations. This model should thus be very useful for the design and development of the next generation of metal hydride hydrogen isotope storage systems.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.4
• /
• pp.497-503
• /
• 2012

The aim of this study was to optimize S-tube shape of heat exchanger in term of reducing the size of tube bundle and improving the mechanical properties such as the thermal stress and resonance. The geometric parameters such as offset length, the straight distance between one end and other end of tube, the tube length in straight portion and fillet radius was assessed as a valid parameters. The structural analysis was performed to estimate the structural characteristics. Main effect analysis was performed to investigate the main effect for the various geometric parameters. The response surface methodology was employed to establish mathematical approximation models as a function of the geometric parameters of the S-tube. Also, The optimization was performed to optimize geometric parameters of S-tube using the regression equations and optimization tool. The optimized tube shape has been proposed. Those could be used in the heat exchanger design used in high temperature.

• Journal of Elementary Mathematics Education in Korea
• /
• v.5 no.1
• /
• pp.55-75
• /
• 2001

The purpose of this paper is to find out the full extent of abilities of elementary students on area of operations and the effects on student's affective domain toward mathematics, after providing 3rd grade students with Skemp's play activities instead of providing activities suggested in the textbook of 7th curriculum. For this study, we will first analyse new elementary mathematics curriculum of 3rd grade and then explore mathematical factors for play activities related to operational sections. The play activities are revised from that of Skemp's for our classroom circumstances, but the ideas included from Skemp's such as thinking aloud were not changed. The experimental group while consists of 39 students were taught Skemp's play activities instead of usual textbook activities for 30 hours for the second term. In all other area, both the experimental group and the comparative group were taught the same contents. Statistical data is as follows 1) In addition and subtraction, the experimental group had 5.6% higher score than the comparative's, but the difference of mean of the both groups is not significant within 5% level. 2) In multiplication and division, the experimental group had 7.8% higher score than the comparative's and also the difference of mean of the beth within 5% level is significant. 3) When measured the effects in affective domain, the interests, attitude, and values for mathematics had about 10% higher score after the experiment than before the experiment. So we conclude that Skemp's activities are more effective than the activities suggested in the textbook on the area of operations, especially in multiplication and division.

• Steel and Composite Structures
• /
• v.16 no.6
• /
• pp.703-718
• /
• 2014

The initial clamping forces of high strength bolts subjected to different faying surface conditions drop within 500 hours regardless of loading, any other external force or loosening of the nut. This study develops a mathematical model for relaxation confined to creep on a coated faying surface after initial clamping. The quantitative model for estimating relaxation was derived from a regression analysis for the relation between the creep strain of the coated surface and the elapsed time for 744 hours. This study establishes an expected model for estimating the relaxation of bolted joints with diverse coated surfaces. The candidate bolts are dacro-coated tension control bolts, ASTM A490 bolt, and plain tension control bolts. The test parameters were coating thickness, species of coating. As for 96, 128, 168, and $226{\mu}m$ thick inorganic zinc, when the coating thickness was increased, relaxation after the initial clamping rose to a much higher range from 10% to 18% due to creep of the coating. The amount of relaxation up to 7 days exceeded 85% of the entire relaxation. From this result, the equation for creep strain can be derived from a statistical regression analysis. Based on the acquired creep behavior, it is expected that the clamping force reflecting relaxation after the elapse of constant time can be calculated from the initial clamping force. The manufacturer's recommendation of inorganic zinc on faying surface as $75{\mu}m$, appears to be reasonable.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.24 no.3
• /
• pp.245-250
• /
• 2014

Addiction can be largely divided into two categories. One is called medium addiction in which medium itself causes an addiction. Another is called cause addiction that brings addiction through combination of sensitive self and latent personal action. The medium addiction involves addiction phenomena directly caused by illegal drugs, alcohol and various other chemicals. The cause addiction is dependent on personal sensitivities as a sensitive problem of personal and includes cyber addictions such as shopping, work, game, internet, TV, and gambling. In this paper we propose two-dimensional addiction model that are equivalent to using an R-L-C series circuit of Electrical circuit and a Spring-Damper-mass of mechanical system. We also organize a Duffing equation that is added a nonlinear term in the proposed two-dimensional addiction model. We represent periodic motion and chaotic motion as time series and phase portrait according to parameter's variation. We confirm that among parameters chaotic motion had addicted state and periodic motion caused by change in control coefficient had pre-addiction state.