• Transactions of Materials Processing
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• v.26 no.4
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• pp.228-233
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• 2017

In flat rolling mills, demands for precise process set-up and control are increasing than ever before. Consequently, it is imperative to establish a novel approach, which would provide valuable information regarding the detailed aspects of deformation behavior of the strip, and rolls during rolling. In this paper, we present a finite element (FE) approach for 3-D coupled analysis of the elastic-plastic deformation of the strip and the elastic deformation of rolls in the roll-stack of a mill stand.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.93-98
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• 2001

This paper studies on the design of an ILQ(Inverse Linear Quadratic optimal control) looper control system for hot strip mills. The looper which is placed between each stand plays an important role in controlling strip width by regulating strip tension variation generated from the velocity difference of main work rolls. The mathematical model for looper is firstly obtained by Taylor's linearization of nonlinear differential equations, where it is given as a linear and time invariant state-space equation. Secondly, a looper servo controller is designed by ILQ control algorithm, which is an inverse problem of LQ(Linear Quadratic optimal control) control. By tunning control gain arbitration parameters and time constants, it is shown that the ILQ looper servo controller has the performance that makes well to follow desired trajectories of both strip tension and looper angle.

• Journal of Korean Society of Forest Science
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• v.72 no.1
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• pp.16-26
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• 1986

Allozyme study on a small pitch pine stand originating and expanded rather rapidly from a few founder trees indicated that the colonization of the pitch pine population was made progressively from the place where the founder trees located to another by moving in cohorts of seeds from a limited number of family or genetically closely related family groups in line with the succeeding generations. This pattern of migration and colonization resulted marked differences in allelic and genotypic frequencies at many of the allozyme loci between the initially colonized subpopulation on the south-facing slope and the lately colonized subpopulation on north-facing slope of a hill. It appeared that gene fixation due to inbreeding and genetic drift occurred at some loci in the pitch pine population or subpopulations. However, even in t 1e inbreeding small pitch pine population or subpopulations, a comparatively large amount of genetic diversity or heterozygosity was maintained due to the high levels of gene recombination at many of the gene loci and natural selections favoring for heterozygotes.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.82-90
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• 2006

To examine the effects of nitrogen and phosphorus fertilization on soil nitrogen (N) mineralization, we monitored rates of soil nitrogen mineralization and nitrification in 41-year-old pitch pine (Pinus rigida Mill.) and Japanese larch (Larix kaempferi Gordon) stands growing on similar soil condition in central Korea. For this study, we used the buried-bag incubation method. Fertilizers were applied at three levels [control (C), 200 N kg/ha+25 P kg/ha (LNP), and 400 N kg/ha+50 P kg/ha(HNP)] on 5 June, 1996. Mineral soils (0~20 cm) were incubated 6 times with 45-day-interval from 5 June 1996 to 4 June 1997. Initial soil moisture contents were significantly different among sampling dates and between tree species. Initial soil moisture contents were 32% for C, 28% for LNP, and 26% for HNP at the P. rigida stand, and 31% for C, 31% for LNP, and 33% for HNP at the L. kaempferi stand, respectively. Mean daily N mineralization rates were significantly different among sampling dates and treatments. Annual net N mineralization and nitrification were also significantly different between the two tree species. The annual net N mineralization was 10.6 kg/ha/year for C, 23.3 kg/ha/year for LNP and 6.6 kg/ha/year for HNP at the P. rigida stand, and 2.0 kg/ha/year for C, 12.1 kg/ha/year for LNP and 16.7 kg/ha/year for HNP at the L. kaempferi stand. The annual nitrification was 2.8 kg/ha/year for C, 7.6 kg/ha/year for LNP and 4.3 kg/ha/year for HNP at the P. rigida stand, and 4.3 kg/ha/year for C, 14.8 kg/ha/year for LNP and 6.6 kg/ha/year for HNP at the L. kaempferi stand. The ratios of annual net nitrification to annual net N mineralization were 26% for C, 33% for LNP, 65% for HNP at the P. rigida stand, and 100% for C, 100% for LNP, 40% for HNP at the L. kaempferi stand, respectively. This study indicates that N mineralization in forest may be different by the predominant tree species and fertilization even under similar environments. It is likely that the quality of organic matter might control nitrogen mineralization and nitrification in soils.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.723-730
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• 1998

With the introduction of edge drop control system in Tandem Cold Rolling Mill, it is necessary to develop te numerical expression for the set-up and edge drop automatic control of cold rolled sheet. As a first step we developed a simulation program which predicts profile and the amounts of edge drop at the delivery side of each stand by using roll deformation anlysis with the slit roll model. And by using the program the effect of various rolling conditions on edge drop was investigated. As a result the relations were obtained between the amounts of edge drop and rolling conditions. Based on above relations, the numerical expression was developed for the set-up and automatic control of edge drop by multi-regression of simulation results for the variation of edge drop amount with each rolling condition.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.561-563
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• 1999

The looper of a hot strip finishing mill is installed between each pair of stands and plays a key role to enhance the product quality of strip by controlling the tension and height of strip in each inter-stand. Though the conventional looper control has achieved the mass products of strip so far, it has difficulties not only tuning gains by means of errors which are caused by coupling effects between strip tension and looper angle both utilizing tension feedback. Therefore, the non-interactive control employing cross controller and tension feedback has been introduced in looper control system in order to overcome the coupling effects existing between tension and looper angle and track the reference tension efficiently. In this paper, we present the cross controllers which play a role to decouple reciprocal effects between tension and looper angle and show better performance.

• Journal of Korea Foresty Energy
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• v.2 no.2
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• pp.1-12
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• 1982

To study tile comparison of aboveground biomass of Pinus rigida Mill. of 18-year-old, plantations located in Whaseong, Yuseong and Wanju district were selected. Ten sample trees in each district selected taking account of DBH distribution were felled carefully to minimize loss of branches and stem analysed by 1m lag segment sectioned from base . The tree height and DBH were measured for sample trees in total growing within $200m^2$ experimental plot. The diagram of oven-dry weight distribution of stem, branch and needle for each 1m segment was constructed. The logarithmic regression equations between dry weight of each component and the two variables, $DBH^2$ and tree height, combined term were presented. The standing crops in the sample stand was estimated to be as much as 23.88, 54.09 and 42.68 tons of dry matter, above ground , per ha in Whaseong, Yuseong anf Wanju district respectively. Annual net production was estimated at 253,657 and 3.65 tons per ha per year respectively. The net assimilation rate was 1.65,1.95 and 1.81 kg/kg/yr in Whaseong, Yuseong and Wanju district respectively. The efficency of leaf to produce stem was 0.99, 1.12 and 1.30 kg/kg/yr respectively.

• Journal of the Korean Society of Food Culture
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• v.28 no.4
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• pp.356-370
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• 2013

The purpose of this study is to examine the Western perspective on the food and food culture of Modern Times in Korea (from the late of Joseon Dynasty until Japanese colonial era). Literature and written records were analyzed. This analysis revealed that the heart of the mill in this period involved rice, and that a common beverage was sungnyung made from boiled scorched rice (in contrast to tea as the common beverage in Japan or China). The most important subsidiary food in Joseon was vegetables, especially Kimchi. Westerners viewed Kimchi as a smell symbolizing Joseon and their meal times. Even though both Kimchi and cheese are fermented food, just like Westerners could not stand the smell of Kimchi, Koreans viewed the smell of cheese unpleasant. Westerners viewed German sauerkraut as Western food counterpart to Kimchi, as sauerkraut is also fermented food made of cabbage. Regarding the eating of dog meat in Joseon, most Westerners viewed it as brutal; however some interpreted it as a difference in food culture. In addition, the eating of raw fish and its intestines felt crude to Westerners. The biggest difference between Joseon's food and Western food was that Joseon had no dairy products and no sugar. The most highly preferred fruit for Westerners was the persimmon, and ginseng was already widely recognized and recorded as a medicinal plant. Joseon's desserts were also favorably evaluated. In contrast, the excessive gluttony, heavy drinking, and unsanitary conditions in Joseon were problems pointed out in many records.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.59-69
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• 2001

Ths paper presents an algorithm of detecting eccentricity signal and diagnosing the cause in rolling process. A designed technique uses only the outputs of load cell and tachorreter, which are generally utilized in rolling process, and need not any acklitional sensors. Detecting signals related to eccentricity is done by combining outputs of 6 digital bandPass filters whose center frequency are varied with roll's rotating frequency. A function of diagnosing the cause of occentricity from extracted data having occentricity components is implemented by defining reasonable variables. In order to show validity of an algorithm designed in this paper, simulation was accomplished for three groups. The first is that some portion of roll in the direction of roll circumference is distorted. The second is that rotating axis and roll center is not identical. The third is that composite cause is occmed Simulation results show that every kind of eccentricity can be diagnosed in terms of algorithm proposed.oposed.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.101-106
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• 2010

CB100 is one of the channel type products in the steel beam. In this study, rolling process of CB100 is analyzed by 3D FEM simulation and rolling process. FEM simulation result is compared with rolling process data. Also the intermediate & finishing roll stress analysis is carried out and the suitability of the roll through roll stress resultant analysis is evaluated. In order to decrease the roll stress, new pass schedule is developed for stable load balance between intermediate and finishing rolling stand. Therefore new rolling pass schedule is verified by the analysis results of rolling process and roll stress. By the analysis results, the credibility of rolling process analysis was obtained and it was determined that the possibility of roll damage between intermediate and finishing mill was high. So the new pass schedule was developed. Through the result of rolling process and roll stress analysis, it was obtained that the reduction of roll stress and stable load balance.