• Title/Summary/Keyword: delayed argument

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Delayed Luminescence of Biophotons from Plant Leaves

  • Sung, Baeck-Kyoung;Yi, Seung-Ho;Lee, Chang-Hoon;Yang, Joon-Mo;Kim, Jai-Soon;Soh, Kwang-Sup;Yang, Jong-Soo
    • Journal of the Optical Society of Korea
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    • v.8 no.3
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    • pp.132-136
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    • 2004
  • Delayed luminescence of plant leaves was imaged by a 2-D cooled charge-coupled device. We report the delayed luminescence imaging of normal/injured leaves picked ami the leaves intact. The luminescent intensity was lower in leaf veins, scars and edge cut. The intensity of delayed luminescence from intact leaves was higher than that of picked leaves. These results indirectly support the argument that the delayed luminescence of a photosynthetic system is closely related to the electron transfer process of PSII in the thylakoid membrane.

A New Technique for Solving Optimal Control Problems of the Time-delayed Systems

  • Ghomanjani, Fateme
    • Kyungpook Mathematical Journal
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    • v.58 no.2
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    • pp.333-346
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    • 2018
  • An approximation scheme utilizing Bezier curves is considered for solving time-delayed optimal control problems with terminal inequality constraints. First, the problem is transformed, using a $P{\acute{a}}de$ approximation, to one without a time-delayed argument. Terminal inequality constraints, if they exist, are converted to equality constraints. A computational method based on Bezier curves in the time domain is then proposed for solving the obtained non-delay optimal control problem. Numerical examples are introduced to verify the efficiency and accuracy of the proposed technique. The findings demonstrate that the proposed method is accurate and easy to implement.

OSCILLATION AND NONOSCILLATION CRITERIA FOR DIFFERENTIAL EQUATIONS OF SECOND ORDER

  • Kim, RakJoong
    • Korean Journal of Mathematics
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    • v.19 no.4
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    • pp.391-402
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    • 2011
  • We give necessary and sufficient conditions such that the homogeneous differential equations of the type: $$(r(t)x^{\prime}(t))^{\prime}+q(t)x^{\prime}(t)+p(t)x(t)=0$$ are nonoscillatory where $r(t)$ > 0 for $t{\in}I=[{\alpha},{\infty})$, ${\alpha}$ > 0. Under the suitable conditions we show that the above equation is nonoscillatory if and only if for ${\gamma}$ > 0, $$(r(t)x^{\prime}(t))^{\prime}+q(t)x^{\prime}(t)+p(t)x(t-{\gamma})=0$$ is nonoscillatory. We obtain several comparison theorems.

The Change of High School Students' Mechanics Conceptions by the Types of Cognitive Conflict Situations (인지갈등 상황 제시유형에 따른 고등학생들의 역학 개념 변화)

  • Lee, Chae-Eun;Lee, Gyoung-Ho;Kim, Ji-Na;Kwon, Jae-Sool
    • Journal of The Korean Association For Science Education
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    • v.21 no.4
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    • pp.697-709
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    • 2001
  • Researchers on conceptual change have been proposed that confronting a cognitive conflict situation would be important for a student to change his/her preexisting conception. There have been reported that there are three different methods of producing a cognitive conflict situation; the first is logical argument(LC), the second is demonstration of an actual phenomenon(DC), and the third is kinesthetic conflict which is a kind of physical experience(EC). In this study, the researcher tried to find out the differences in the conceptual changes by the three different conflict situations. Seventy two high school students were chosen in a high school in Kyungkido, Korea. The students were tested four times; pretest, posttest, one week delayed posttest, and one month delayed posttest. Six different test situations on mechanics were developed for this study. Test item for each situation was developed. Each item consisted of a multiple choice question and explanation of the choice. The result showed a clear differences among the three conflict groups. In general, kinesthetic conflict which is a kind of physical experience(EC) was proved to be the most efficient strategy for the conceptual change; however, logical argument(LC) seemed to be the least efficient. However, the effectiveness was not uniform from situation to situation. Results of some items showed that even the LC was quite good for the conceptual change. Therefore, it seems to be important to develope appropriate method for the target concept.

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The Influence of the Types of Scientific Concepts and the Patterns of Cognitive Conflict on the Change of Students Conceptions (과학개념과 인지적 갈등의 유형이 학생들의 개념변화에 미치는 영향)

  • Kim, Beom-Ki;Kwon, Jae-Sool
    • Journal of The Korean Association For Science Education
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    • v.15 no.4
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    • pp.472-486
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    • 1995
  • The purpose of this study was to classify the types of scientific concepts by theoretical concepts and empirical concepts in physics, and to create cognitive conflict in students with logical statements and demonstrations, and to investigate conceptual changes. It seems that mechanics has much to do with the empirical concepts, and electromagnetics has much to do with the theoretical concepts. The condition of the instrument is intellegible, plausible, fruitful, and able to state and demonstrate. The instrument appropriate for these conditions was developed, which consisted of 6 items in mechanics and 6 items in electromagnetics, and conceptual changes were investigated. Structured interviews were conducted with 32 high school students to create cognitive conflict. We have elicited their ideas three times : pretest, posttest and delayed posttest. As the results of this study, demonstration method was more effective for conceptual change than logical argument method. In case of content areas, the misconceptions on mechanics concepts were changed more easily than those on electromagnetics concepts. In addition, the results of the study showed that the more cognitive conflict, the more the conceptual change was occurred.

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The Effects of Cognitive Conflict on Students' Conceptual Change in Physics

  • Lee, Young-Jick;Kwon, Jae-Sool
    • Journal of The Korean Association For Science Education
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    • v.22 no.5
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    • pp.923-943
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    • 2002
  • The purpose of this study was to investigate the relation between the levels of cognitive conflict and students' conceptual change. In this study, 30 Korean high school students were selected from 450 10th graders by examining the pretest results. Two different strategies were used to induce cognitive conflicts in students, an anomalous or conflict situations; demonstrations and logical arguments against students' preconception. After arousing the students' cognitive conflict, the level of cognitive conflict was rated. Pretest, post-test and delayed post-test were administered to check the conceptual change. The tests consisted of 5 items in mechanics and electricity, respectively. Therefore, the demonstration method showed effective conceptual change, more than the logical argument method did. Students changed their conceptions more easily and frequently in the area of mechanics than in electricity. Students who showed higher levels of cognitive conflict indicated more positive conceptual change than those who showed lower conflict levels. 59 cases (56%) out of 105 who experienced high levels of cognitive conflict were changed into scientific conceptions one month later; however only 16 cases (35%) out of 46 who experienced low levels of cognitive conflict changed into scientific conceptions. Students who experienced higher levels of cognitive conflict showed higher rates of conceptual change. It could be concluded that designing instruction to induce cognitive conflict is a useful strategy to promote conceptual change.

The Impact of Educational Attainment on First Marriage Formation: Marriage Delayed or Marriage Forgone? (교육이 초혼 형성에 미치는 영향: 결혼 연기 혹은 독신?)

  • Woo, Hae-Bong
    • Korea journal of population studies
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    • v.32 no.1
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    • pp.25-50
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    • 2009
  • Using the Korean labor and Income Panel Study, this study examines the impact of educational attainment on first marriage formation in Korea. In particular, this study examines whether higher education is associated primarily with delayed marriage or with a higher likelihood of never marrying. The results show that the trend toward later and less marriage is occurring at all levels of educational attainment in Korea. The data also indicated that educational attainment showed differential effects on the risk of first marriage formation for Korean men and women. For those born before 1970, both highly educated men and women delayed marriage but caught up by marrying at higher rates at later ages. However, for those born after 1970, highly educated women were increasingly more likely to show the trend toward later and less marriage, while highly educated men were more likely to delay marriage but caught up by marrying at higher rates at later ages. Overall the evidence in this study is consistent with the argument that gender divisions make it difficult for women to balance work and family in Korea.

Effect of the Civil Servant's Suspension of Pension Payments on the Labor Supply and Suggestions on Developmental Alternatives of Suspension of Pension Payments (공무원연금의 지급정지제도가 가입자의 노동공급에 미치는 영향 및 지급정지제도의 발전방향 모색)

  • Ji, Eun-Jeong
    • Korean Journal of Social Welfare
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    • v.57 no.2
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    • pp.375-403
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    • 2005
  • This Study reviews theoretical argument about the effect of retirement earnings test on the labor supply of the aged which is controversial issue in OECD countries and analyze the effect on the incidence of re-employment, re-employment period of suspended officials and the possibility of re-retirement through Government Employment Pension Corporation data. It consists of 178,363 public officials who received pension benefit or disability pension in January 2005. The main result of this research shows that public officials re-employed were 8,086 which is 4.5% of total retired, and median survival time of suspended pension payments is 3.3 years. Also the median re-employment period of 100% suspended officials is about 20 month shorter than that of 1/2 suspended officials and it is shown in regression analysis that the possibility of re-retirement by 100% suspended officials is statistically significant higher than those of 50%. It specially expects greater influence if includes in case taking lump-sum or no making effect of re-employment because current system withhold pension payments even by earned income itself. Therefore, this analysis suggests suspension of pension payment properly applied according to the age and income together with "Delayed Retirement Credit" or "Partial Pension" for developmental alternatives of civil servant's suspension of pension payments. Furthermore, It is urgently needed that distinctive quality data about re-employment including earnings to perform deep-empirical research for effective policy. Lastly, it is extremely necessary to reinforce management system of Government Employment Pension Corporation.

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Current Status of Korean Ginseng Research (한국인삼론(韓國人蔘論))

  • Han, Byung-Hoon
    • Korean Journal of Pharmacognosy
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    • v.3 no.3
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    • pp.151-160
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    • 1972
  • Recent achievements of scientific research on the pharmacologic activities and the chemical problems of dammalene glycosides, which are considered to be effective principles of Korean ginseng, are reviewed and analyzed in view of structure-activity relationship. 1) S. Shibata and his co-workers detected 12 glycoside spots of dammalene series on the two dimensional T.L.C. of total glycoside fraction from Japanese ginseng, and designated them Ginsenoside Rx(x=a, b, c, g, h, etc.) in the order of increasing Rf-value. The aglycones of those glycosides were characterized to be protopanaxadiol for the Ginsenoside $Rx(x=a,\;b_{1},\;b_{2},\;c,\;d,\;e,\;f)$ and protopanaxatriol for the Ginsenoside $Rx(x=g_{1},\;g_{2},\;g_{3},\;h_{1}\;'h_{2})$. Using Korean ginseng as the material for our study, the author and his coworkers isolated a new dammalene glycoside(Panax Saponin C), which comes under the category of protopanaxadiol glycosides based on the classification of S. Shibata et al., and characterized this saponin to be the glycoside of protopanaxatriol series. Furthermore, Panax Saponin C dissociated into $two\;components(C_{1}\;and\;C_{2}-acetate)$ by acetylation, both of which returned to original Panax Saponin C by deacetylation. Based on this result, more than 13 glycoside components of dammalene series will be expected in the Korean ginseng. 2) The structures of protopanaxadiol and protopanaxatriol, the genuine aglycones of dammalene glycosides, are fully established to be structural analogues by S. Shibata and his co-workers, therefore antagonistic and/or analogical activities will be expected for the pharmacologic activities of these glycoside series of structural analogues. K. Takaki and his co-workers found central nervous system (CNS) stimmulant activity from the glycosides of protopanaxatriol series and CNS-depressant activity from the glycosides of protopanaxadiol series. On the other hand, the author and his co-workers found stimmulating activity on the protein synthesis from both the series of dammalene glycosides with delayed and long-lasting characteristics. This delayed and long-lasting characteristics were also observed in the anti-inflammatory activity of glycosides of protopanaxatriol series on their time course tendency. For the convenience's sake of argument, pluralistic pharmacologic activities of dammalene glycosides, which were observed by many workers at various pharmacologic site, may be classified into two main categories; one is pan-cellular activity and the other is organ specific activity to the certain tissue which is a mass of cells differentiated to a certain direction for their special functions in the body. Based on the data of K. Takaki and those of the authors, following assumption will be probable; Pharmacologic activities of both series of glycosides of protopanaxadiol and protopanaxatriol aglycones may be antagonistic on their tissue-specific activities and analogic on their pan-cellular activities. Therefore, the mixture of these two series of glycosides in an appropriate ratio, as the case of total extract of Korean ginseng, will be probably beneficial to the host by increasing the synthesis of some functional proteins, due to the additive action of pan-cellular activity, and with the disappearance of any significant behavioral symptoms due to the antagonism of tissue specific activity. This fact will probably be the main reason why classical trials of pharmacologists failed in re-discovering the efficacy of Korean ginseng with their behavioral test. 3) The author and his co-workers achieved the synthesis of $C^{14}-labelled\;Panax\;Saponin\;A\;on\;C_{25}-C_{27}\;position\;of\;aglycone$ in the interest of tracer studies in vivo. The method will be applicable to other dammalene glycosides regardless of their chemical structure. 4) The author and his co-workers converted chemically betulafolienetriol, a triterpene component of Betula platyphylla, to the protopanaxadiol, one of genuine aglycone of dammalene glycosides.

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