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Context-Based Design and Its Application Effects in Science Classes (맥락을 중요시하는 과학 수업 전략의 개발 및 적용)

  • Jung, Suk-Jin;Shin, Young-Joon
    • Journal of Korean Elementary Science Education
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    • v.43 no.1
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    • pp.48-63
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    • 2024
  • This study aims to develop a class procedure for the application of classrooms that value context and to conduct science classes using this procedure to examine the effects. Among various contexts related to scientific knowledge, the study develops a teaching procedure for designing classes that focus on the contexts of discovery and real life. After verifying the content validity of the context-based design and the program to which it was applied, a class was conducted, and the responses of the children were checked. The final draft of the lesson design completed after revision and supplementation is as follows: context-based design was presented in four stages, namely, presenting, exploring the context, adapting the context, and organizing (share and synthesizing; PEAS). The goal is to enable people to experience the overall flow of scientific knowledge instead of focusing on the acquisition of fragmentary knowledge by covering a wide range of topics from the social and historical contexts in which scientific knowledge was created to its use in real life. To aid in understanding the newly proposed class procedure and verifying its effectiveness, we developed a program by selecting the "My Fun Exploration," 2. Biology and Environment unit of the second semester of the fifth grade. The result indicated that the elementary science program that applied the context-centered design effectively improved the self-directed learning ability of students. In addition, the effect was especially notable in terms of intrinsic motivation. As the students experienced the contexts of discovery and real life related to scientific knowledge, they developed the desire to actively participate in science learning. As this becomes an essential condition for deriving active learning effects, a virtuous cycle in which meaningful learning can occur has been created. Based on the implications, developing programs that apply context-based design to various areas and contents will be possible.

The Essence and Significance of the Concept of 'Return to the Former World' in Donghak-gyo (동학교 '도로 선천(先天)'사상의 내용과 의의)

  • Kim Tak
    • Journal of the Daesoon Academy of Sciences
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    • v.48
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    • pp.199-237
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    • 2024
  • Donghak-gyo, the Teaching of Eastern Learning, is a new religious order founded by Kim Ju-hee, centered around the Donghak (Eastern Learning) lineage. The core thought conveyed in the lyrics of Donghak-gyo songs (gasa) can be identified as the concept of 'Return to the Former World (先天),' considering the frequency of the term and the content of the recited verses. The view of time and destiny (時運觀) held by Eastern Learning emphasizes the concept of 'Another Great Opening.' Donghak-gyo's perspective on time and destiny is further rooted in the concept of 'Return to the Former World.' Donghak-gyo particularly emphasizes the term 'Former World,' and incorporates the Study of Changes (易學) into their songs. They recite verses that depict the situation of the Great Opening as an interaction between yin and yang. In Donghak-gyo, it is emphatically asserted that the completion of the Later World's destiny leads to the achievement of the 'Return to the Former World.' It is sung that with the restoration of destiny associated with the 'Return to the Former World,' the symbolic 'Spring (春)' represented by the virtue of Wood (木德) will return. Donghak-gyo describes the unfolding of a new cycle of destiny (運數) as the 'restoration of Changes (易).' When this occurs, they refer to the emerging new world, characterized by a new order and norms, as the 'Return to the Former World,' asserting that a 'moral world' will be established, leading to the development of a moral civilization. It is also sung that the restoration of the destiny associated with the Return to the Former World is akin to the restoration of the Heavenly Dao (天道). The characteristics of the concept of the Return to the Former World are threefold: firstly, it advocates a nostalgic system; secondly, it is a backward-looking thought; and thirdly, the idea of 'cyclical repetition' encourages tangible actions such as 'returning to the origin' or 'restoring fundamentals.' The concept of Return to the Former World in Donghak-gyo, unlike many new religions of those days, provided a unique conceptualization and understanding of the Former World and presented a new framework for interpretation. It moved away from the notion of discarding the Former World as a relic of an outdated era, and instead interpreted it as a new era to be embraced. Therefore, the concept of 'Return to the Former World' in Donghak-gyo should be re-assessed as one of the ideologies that inherits the pursuit of returning to and restoring the past in Eastern traditions. However, it can be criticized for lacking a concrete methodology with regards to the 'Return to the Former World.' Additionally, it is noted for deficiencies in ethical consciousness and moral virtues. Furthermore, its explanation about the Former World come across as insufficient. Thus, the concept of the 'Return to the Former World' in Donghak-gyo seems to be characterized more by declarative slogans than substantive content.

CHOBUN, Understanding the Double Burial Custom in Korea from a Jungian Perspective : Focusing on Putrefaction and Reduction to Bones (초분, 한국 이중장제의 분석심리학적 고찰 : 부패와 뼈로의 환원을 중심으로)

  • Jahyeon Cho
    • Sim-seong Yeon-gu
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    • v.31 no.2
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    • pp.113-150
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    • 2016
  • Chobun refers to a temporary grave covered with straw thatch that contains a corpse until its flesh is gone. When all the flesh has rotted away, the straw grave is disassembled and only the bones are retrieved. Therefore, Chobun is an example of a secondary burial custom (German : Doppel Bestattung) that is composed of a first temporary funeral for processing the corpse's flesh, and a second permanent burial of the final remains (bones or ashes). The duration of the temporary burial is determined by the time needed for decomposing the flesh of the deceased. Building a Chobun progresses putrefaction and reduction to bone. In the literature of alchemy, putrefaction and new life occur simultaneously. The purpose of rotting is to make the flesh disappear, leaving only its essence. It is making the physical body enter a spiritual state, so that the dead can enter into a different world. One must endure the unstable rotting process until the smell of flesh has faded. The rotting process is the attitude of accepting the terrible, polluted aspect of the corpse, while maintaining a helpless, passive posture, in order to allow new possibilities. When we try to approach an archetypal aspect of the unconscious, it is often experienced in threatening, aggressive ways. In the individuation process, the unconscious offers us the blessing of a new spiritual awakening and renewed sense of life, only when we have the courage to see this terrifying and contaminated side of our psyche. This is exactly what putrefaction means. Bone and skeleton symbolize the indestructible, imperishable, and essential elements of life. Bone is the minimum unit and foundation for regeneration, where new life can grow. Reduction to bone is moving back to the origin of life, to the womb. Psychologically, it means discarding one's ego-centeredness and allowing the Self to lead the entire process of individuation. Going through the painful process of reduction to a skeleton for the purpose of further development is a declaration of the death of the ego, aiming at the liberation from perishable flesh and acquisition of the spiritual, regenerative, and immortal elements of life. Chobun also denotes the yearly decay and revival of life, especially of vegetal life. In Chobun, this symbolic meaning of the vegetal cycle of life is emphasized to represent the part of life that survives even after death. Vegetation related to Chobun deals with the continuity of life and psychologically with the Self. Images of vegetation are closely related to the existence of life beyond death, which is the existence of the Self, the source of energy that constantly renews and rejuvenates the consciousness.

Actual Experience of the Oracle of the I Ching-Death, God and Love: In Front of My Father's Spirit (주역 점(占)의 실제 체험-죽음, 신 그리고 사랑: 아버지의 영전(靈前)에서)

  • Ju Hyun Lee;Bou-Yong Rhi
    • Sim-seong Yeon-gu
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    • v.37 no.2
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    • pp.149-183
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    • 2022
  • The oracle of the I Ching, divination can be understood as 'synchronicity phenomenon' in analytic psychology. In order to experience divination actually, it requires a religious attitude that asks questions with a serious mind when a person is in trouble that consciousness reaches its limit. It is not just a passive attitude, but a modest, active attitude to ask what I can do now. The experience of the oracle of the I Ching connected to supra-consciousness is similar to 'active imagination'-talking with the archetype of collective unconsciousness-and is 'the process of finding the rhythm of Self-archetype, the absolute wisdom of unconsciousness.' One month before my father's death, I took care of him who couldn't communicate verbally and I divination with a question 'What can I do for my father and me now?' The I Ching's answer was hexagram 19 Lin 臨, nine at the beginning. It's message was '咸臨貞吉 joint approach. perseverance brings good fortune.' 志行正也 we must adhere perseveringly to what is right.' Through this phrase, I learned the attitude of waiting for life after death as if 'joyful obedient' to the providence of nature that spring comes after winter. And I found that keeping the touching emotion of meeting infinity (in analytical psychological terms, 'Self') with perseveration is to do the true meaning of life beyond popular money-mindedness. And six months before my father's death, I had a dream about the afterlife. In the process of interpreting that dream, I learned not only from the shock of the direct message that 'it is a truth that there is something after death,' but also the regeneration of the mind through introversion from the similarity between the closed ward and '黃泉'-chinese underworld through amplification. And I learned the importance of an open attitude to accept new things through the 'window to eternity' symbolized by the white iron gate. In my father's catholic funeral ritual, I had hope that the catholic doctrine 'Communio Sanctorum'-A spiral cycle in which the living and the dead help each other may be real as well as a symbol of the individuation process in which consciousness and unconsciousness interact in our minds. Through the consolation received through the funeral visit of many people I met in my life, I found the answer that the path to contact with infinity begins with loving the beings in front of me. I tried to understand this continuous experience by the perspective of analytical psychology.

State of Health and State of Charge Estimation of Li-ion Battery for Construction Equipment based on Dual Extended Kalman Filter (이중확장칼만필터(DEKF)를 기반한 건설장비용 리튬이온전지의 State of Charge(SOC) 및 State of Health(SOH) 추정)

  • Hong-Ryun Jung;Jun Ho Kim;Seung Woo Kim;Jong Hoon Kim;Eun Jin Kang;Jeong Woo Yun
    • Journal of the Microelectronics and Packaging Society
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    • v.31 no.1
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    • pp.16-22
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    • 2024
  • Along with the high interest in electric vehicles and new renewable energy, there is a growing demand to apply lithium-ion batteries in the construction equipment industry. The capacity of heavy construction equipment that performs various tasks at construction sites is rapidly decreasing. Therefore, it is essential to accurately predict the state of batteries such as SOC (State of Charge) and SOH (State of Health). In this paper, the errors between actual electrochemical measurement data and estimated data were compared using the Dual Extended Kalman Filter (DEKF) algorithm that can estimate SOC and SOH at the same time. The prediction of battery charge state was analyzed by measuring OCV at SOC 5% intervals under 0.2C-rate conditions after the battery cell was fully charged, and the degradation state of the battery was predicted after 50 cycles of aging tests under various C-rate (0.2, 0.3, 0.5, 1.0, 1.5C rate) conditions. It was confirmed that the SOC and SOH estimation errors using DEKF tended to increase as the C-rate increased. It was confirmed that the SOC estimation using DEKF showed less than 6% at 0.2, 0.5, and 1C-rate. In addition, it was confirmed that the SOH estimation results showed good performance within the maximum error of 1.0% and 1.3% at 0.2 and 0.3C-rate, respectively. Also, it was confirmed that the estimation error also increased from 1.5% to 2% as the C-rate increased from 0.5 to 1.5C-rate. However, this result shows that all SOH estimation results using DEKF were excellent within about 2%.

Characteristics of New Microsporidia S80 Isolated from Silkworm, Bombyx mori L. in Korea (가잠(家蠶)으로부터 분리(分離)된 새로운 Microsporidia S80의 특성(特性))

  • Lim, Jong Sung;Cho, Sae Yun
    • Current Research on Agriculture and Life Sciences
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    • v.1
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    • pp.67-83
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    • 1983
  • The new microsporidia S80 isolated from, Bombyx mori L. in Korea showed ovoid in the morphology of the spores and the size were measured $2.9{\pm}0.28{\mu}$ in length and $1.7{\pm}0.29{\mu}$ width. No other microsporidian spore like this has not been so far isolated from Silkworm. The length of the polar filament extruded in hydrogen peroxide ($H_2O_2$) at $30^{\circ}C$ was $26{\mu}$ of a round cytoplasm on the top. The spores were partly stained with Giemsa, Safranin-O and Gram as the same staining properties as Nosema bombycis, Microsporidia K 79 and other microsporidian spores. The fine structures were observed under scanning eleceron microscope through ultrathin sectioning. The spore wall was composed of three layers ; the thin exospore of an electron dense rippled layer, the thick electron lucent endospore which was thinning considerably at the polar filament insertion point, and the inner limiting membrane. Polar cap present at the sporeapex, with a long polar filament of 12-13 coils, subtending angle of $60^{\circ}$ to spore axis, which is tubular made up of a multilayered and are a benes core, light ring structure enclosing the dance core, the dark ring structure enclosing the inner light ring structure and the other than and light ring structure bounded from cytoplasm. Lamellate polaroplast occupied the anterior part of the spore, and the two neclei with dense nucleoplasm bounded by a double nuclear envelope were cited in the slight downer middle portion of spore. From the characteristics of the shape, size and fine structures, it is certain to reason the Microsporidia S80 belong to the phylum Microspora, class Microspora, order Microsporida, order Microsporida. The shape of two nuclei cited seems to be genus Nosema, but in the classification for the suborder it should be defined wheather pansporoblasts be formed or not and for the genis especial attempts have been made to define the characters which distinguish the disporous genera in the life cycle. Survey through the infection of the bad cocoons during 1980 to 1982 in South Korea the areas contaminated with new microsporidia were revealed 5 provinces of Kyung-Gi, Kang-Won, Chung-Nam and Chun-Nam. Pathological effects inoculated per os at second instar larvae of silkworm, the LD 50 was $7.1{\times}10^7/ml$ as lower pathogenecity than that of Nosema bombycis Naegeli of $1.2{\times}10_7/ml$. While on the other hand the inoculation of the microsporidia at fourth instar larvae lowerd the whole cocoon weight and cocoon shell weight and significant at 1% level. The microsporidia S80 defined it can not be transmitted transovarially from the result of predictive and collective examination of 21 egg batches from the infected female moth.

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Stock Identification of Todarodes pacificus in Northwest Pacific (북서태평양에 서식하는 살오징어(Todarodes pacificus) 계군 분석에 대한 고찰)

  • Kim, Jeong-Yun;Moon, Chang-Ho;Yoon, Moon-Geun;Kang, Chang-Keun;Kim, Kyung-Ryul;Na, Taehee;Choy, Eun Jung;Lee, Chung Il
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.17 no.4
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    • pp.292-302
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    • 2012
  • This paper reviews comparison analysis of current and latest application for stock identification methods of Todarodes pacificus, and the pros and cons of each method and consideration of how to compensate for each other. Todarodes pacificus which migrates wide areas in western North Pacific is important fishery resource ecologically and commercially. Todarodes pacificus is also considered as 'biological indicator' of ocean environmental changes. And changes in its short and long term catch and distribution area occur along with environmental changes. For example, while the catch of pollack, a cold water fish, has dramatically decreased until today after the climate regime shift in 1987/1988, the catch of Todarodes pacificus has been dramatically increased. Regarding the decrease in pollack catch, overfishing and climate changes were considered as the main causes, but there has been no definite reason until today. One of the reasons why there is no definite answer is related with no proper analysis about ecological and environmental aspects based on stock identification. Subpopulation is a group sharing the same gene pool through sexual reproduction process within limited boundaries having similar ecological characteristics. Each individual with same stock might be affected by different environment in temporal and spatial during the process of spawning, recruitment and then reproduction. Thereby, accurate stock analysis about the species can play an efficient alternative to comply with effective resource management and rapid changes. Four main stock analysis were applied to Todarodes pacificus: Morphologic Method, Ecological Method, Tagging Method, Genetic Method. Ecological method is studies for analysis of differences in spawning grounds by analysing the individual ecological change, distribution, migration status, parasitic state of parasite, kinds of parasite and parasite infection rate etc. Currently the method has been studying lively can identify the group in the similar environment. However It is difficult to know to identify the same genetic group in each other. Tagging Method is direct method. It can analyse cohort's migration, distribution and location of spawning, but it is very difficult to recapture tagged squids and hard to tag juveniles. Genetic method, which is for useful fishery resource stock analysis has provided the basic information regarding resource management study. Genetic method for stock analysis is determined according to markers' sensitivity and need to select high multiform of genetic markers. For stock identification, isozyme multiform has been used for genetic markers. Recently there is increase in use of makers with high range variability among DNA sequencing like mitochondria, microsatellite. Even the current morphologic method, tagging method and ecological method played important rolls through finding Todarodes pacificus' life cycle, migration route and changes in spawning grounds, it is still difficult to analyze the stock of Todarodes pacificus as those are distributed in difference seas. Lately, by taking advantages of each stock analysis method, more complicated method is being applied. If based on such analysis and genetic method for improvement are played, there will be much advance in management system for the resource fluctuation of Todarodes pacificus.

Ecological Characteristic between the Re-introduction Population and the Original Population (Jojong Stream, Sudong Stream) of Zacco koreanus in the Bongseonsa Stream, Korea (봉선사천의 참갈겨니(Zacco koreanus) 재도입 개체군과 원개체군(조종천, 수동천) 간 생태학적 특징)

  • Wang, Ju-Hyoun;Choi, Jun-Kil;Lee, Hyuk-Je;Lee, Hwang-Goo
    • Korean Journal of Environment and Ecology
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    • v.31 no.6
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    • pp.537-548
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    • 2017
  • The purpose of this study was to investigate the species composition and the aquatic environment of Jojong Stream and Sudong Stream, which were the original habitats of Zacco koreanus population and restored population re-introduced in Bongseonsa Stream. It also compared and analyzed the states of the growth and reproductive ability of Z. koreanus habiting in each of the three streams. The investigation was conducted in June 2016 which was known as the spawning season of Z. koreanus. The results of the physical aquatic environments showed the slight differences in altitude, width and depth of water among three streams, but the bottom structure was found to be quite different in the composition of the boulder, cobble, and pebble among the streams. The result of the physicochemical aquatic environment analysis showed that there were no significant differences in water temperature, pH, DO, BOD, and EC among the three stream. In the fish fauna investigation, 530 individuals of 11 species of 3 families were collected in Bongseonsa Stream, 293 individuals of 12 species of 4 families were collected in Jojong Stream, and 361 individuals of 11 species of 4 families were collected in Sudong Stream. All three streams were dominated by Z. koreanus and Z. platypus. Six Korean endemic species appeared in each of the three streams, showing the high occurrence rate of indigenous species of 50.0% or more. The aggregation index analysis revealed that the mean dominance index ranged from 0.63 (${\pm}0.05$, BS) to 0.72(${\pm}0.01$, JJ), mean diversity index from 1.55 (${\pm}0.06$, JJ) to 1.78 (${\pm}0.11$, BS), mean evenness index from 0.71 (${\pm}0.03$, JJ) to 0.76 (${\pm}0.02$, BS), and mean richness index from 1.61 (${\pm}0.33$, JJ) to 1.73 (${\pm}0.24$, SD). The result indicated that the observed differences between the stream community indices were statistically nonsignificant. The similarity analysis showed that 75.4% similarity was divided into two groups of A and B and that the fish fauna on each analyzed point was similar. The quantitative habitat evaluation index (QHEI) analysis showed that the average value of QHEI was 151.0 (${\pm}46.0$), which means that it was a suboptimal habitat environment. The result of length-weight analysis of Z. koreanus populations showed that the regression coefficient b of the restoration population and the original habitat population were at 3.0 or higher while the condition factor had a positive slope. Moreover, it was found that the slopes of the regression coefficient b and condition factor of the original habitat population were larger than the restored population. The analysis of the length frequency distribution of the Z. koreanus population revealed that all three streams maintained the stable life cycle although it was found that the growth rate of the original habitat population was faster than the restored population in the one-year-old class. The result of the gonadosomatic index (GSI) analysis showed that the GSI median value of the Z. koreanus population in the restored habitat Bongseonsa Stream was higher than the population in the original habitat Jojong Stream and Sudong Stream for both of males and females.

A Study on Web-based Technology Valuation System (웹기반 지능형 기술가치평가 시스템에 관한 연구)

  • Sung, Tae-Eung;Jun, Seung-Pyo;Kim, Sang-Gook;Park, Hyun-Woo
    • Journal of Intelligence and Information Systems
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    • v.23 no.1
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    • pp.23-46
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    • 2017
  • Although there have been cases of evaluating the value of specific companies or projects which have centralized on developed countries in North America and Europe from the early 2000s, the system and methodology for estimating the economic value of individual technologies or patents has been activated on and on. Of course, there exist several online systems that qualitatively evaluate the technology's grade or the patent rating of the technology to be evaluated, as in 'KTRS' of the KIBO and 'SMART 3.1' of the Korea Invention Promotion Association. However, a web-based technology valuation system, referred to as 'STAR-Value system' that calculates the quantitative values of the subject technology for various purposes such as business feasibility analysis, investment attraction, tax/litigation, etc., has been officially opened and recently spreading. In this study, we introduce the type of methodology and evaluation model, reference information supporting these theories, and how database associated are utilized, focusing various modules and frameworks embedded in STAR-Value system. In particular, there are six valuation methods, including the discounted cash flow method (DCF), which is a representative one based on the income approach that anticipates future economic income to be valued at present, and the relief-from-royalty method, which calculates the present value of royalties' where we consider the contribution of the subject technology towards the business value created as the royalty rate. We look at how models and related support information (technology life, corporate (business) financial information, discount rate, industrial technology factors, etc.) can be used and linked in a intelligent manner. Based on the classification of information such as International Patent Classification (IPC) or Korea Standard Industry Classification (KSIC) for technology to be evaluated, the STAR-Value system automatically returns meta data such as technology cycle time (TCT), sales growth rate and profitability data of similar company or industry sector, weighted average cost of capital (WACC), indices of industrial technology factors, etc., and apply adjustment factors to them, so that the result of technology value calculation has high reliability and objectivity. Furthermore, if the information on the potential market size of the target technology and the market share of the commercialization subject refers to data-driven information, or if the estimated value range of similar technologies by industry sector is provided from the evaluation cases which are already completed and accumulated in database, the STAR-Value is anticipated that it will enable to present highly accurate value range in real time by intelligently linking various support modules. Including the explanation of the various valuation models and relevant primary variables as presented in this paper, the STAR-Value system intends to utilize more systematically and in a data-driven way by supporting the optimal model selection guideline module, intelligent technology value range reasoning module, and similar company selection based market share prediction module, etc. In addition, the research on the development and intelligence of the web-based STAR-Value system is significant in that it widely spread the web-based system that can be used in the validation and application to practices of the theoretical feasibility of the technology valuation field, and it is expected that it could be utilized in various fields of technology commercialization.

Effect of Strength Increasing Sizes on the Quality of Fiberboard (섬유판(纖維板)의 증강(增强)사이즈제(齊)가 재질(材質)에 미치는 영향(影響))

  • Shin, Dong So;Lee, Hwa Hyoung
    • Journal of Korean Society of Forest Science
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    • v.30 no.1
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    • pp.19-29
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    • 1976
  • The fiberboard and paper mills in this country are much affected by the price hikes and shortage of phenolic resins, since phenolic acid as a raw material depends on imported good. It is prerequisite to fiberboard industry to help replace with other sized and stabilize the prices and supply of them, improving the quality of boards. Thus, the present study was carried out to examine the effect of strength increasing sized such as urea formaldehyde resin (anion and cation type) and urea melamine copolymer resin, on the quality of the wet forming hardboard, and comparing them with two types of proprietary modified melamine resins, and ordinary size, phenol resin. The Asplund pulp was prepared from wood wastes mixed with 20 percent of lauan and 80 percent of pines as a fibrous material. After sizing agents were added at a pH of 4.5 for 10 minutes with alum in the beater, the stock was made in the form of wet sheet, prepared, and then performed by hot pressing cycle: $180^{\circ}C$, $50-6-5kg/cm^2$, 1-2-7 minutes. The properties of hardboard were examined after air conditioning. The results obtained are summarized as follows: 1. There is a significant difference in specific gravity among hardboards that were treated with strength increasing resins, but no difference is effected by the increase in the resin content. In the case of modified melamine resin, its specific gravity is highest. The middle group comprises cation type of urea resin, anion type of urea resin, and acid colloid of urea-melamine copolymer resin. The lowest is phenolic resin. 2. The difference of the moisture content of hardboard both by the resins and by the amount of each resin applied is significant. The moisture content of hardboard becomes lower along with the increase of each resin content, but there is no difference between 2 and 3 percent. 3. For water absorption, there is a significant difference both in the adhesives used and in the amount of paraffin wax emulsion. The water resistance becomes higher inn proportion to the content of the paraffin wax emulsion. To satisfy KS F standards of the water resistance, a proprietary modified melamine resin (p-6100) and modified cation type of urea resin (p-1500) do not require any paraffin wax emulsion, but in the case of anion type of urea resin, cation type of urea resin, and urea-melamine copolymer resin, 1 percent of paraffin wax emulsion is needed, and 2 percent of paraffin wax emulsion in the case of phenolic resin. 4. The difference of flexural strength of hardboard both by the resins and by the amount of each resin is significant. Modified melamine resin shows the highest degree of flexural strength. Among the middle group are urea-melamine copolymer resin, p-1500, anion type of urea resin, and cation type of urea resin. Phenolic resin is the lowest. The cause may be attributable to factors combined with the pressing temperature, sizing effect, and thermal efficiency of press platens heated electrically. 5. Considering the economic advantages and properties of hardboard, it is proposed that urea-melamine copolymer resin and cation type of urea resin be used for the development of the fiberboard industry. It is desirable to further develop the modified urea-melamine copolymer resin and cation type of urea resin through continuous study.

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