• Title/Summary/Keyword: Structure and function

Search Result 6,626, Processing Time 0.036 seconds

The Effects of Female Wage on Fertility in Korea (여성의 임금수준이 출산율에 미치는 영향 분석)

  • Kim, Jungho
    • KDI Journal of Economic Policy
    • /
    • v.31 no.1
    • /
    • pp.105-138
    • /
    • 2009
  • Although the decline in fertility rate is generally observed along the history of economic development throughout the world, the continuing decline hitting below the replacement level in Korea over the recent years gathered serious social concerns on the ground that it accelerates the process of population aging. The total fertility rate in Koreareached 2.08 in 1983, and gradually fell to the levels of 1.08 in 2005 and 1.26 in 2007. The policy debate over the role of the government has been focused mainly on the level of theoretical discussion without substantial basis on firm empirical evidence and the determinants of fertility. The objective of the paper is to empirically investigate the fertility effect of the female wage, which is understood as one of the most important determinants of fertility in Koreasince 1980 focusing on one aspect of fertility, namely birth spacing. Using the Korean National Fertility Survey conducted in 2006, I estimate a duration model of first and second births taking into account individual heterogeneity, which turned out to be an important factor to control for. Compared with previous studies in the literature on the Korean fertility, the study has an advantage of using the complete pregnancy history of women in a more representative sample. Unlike the previous studies, the analysis also deals with the endogeneity of marriage by treating a certain age, rather than age at marriage, as the time in which a woman becomes exposed to the risk of pregnancy. The study shares the common problem in the literature on birth spacing of lacking relevant wage information for respondents in a retrospective survey. I estimate the wage series as a function of the basic characteristics using the annual Wage Structure Survey from 1980 to 2005, which is considered as a nationally representative sample for wage information of employees. The results suggest that the increase in female wage by 10 percent leads to a decrease in second birth hazard by 0.56~0.92 percentage points and that the increase in spouse's wage by the equal amount is accompanied by the increase in second birth hazard by 0.36~1.13 percentage points. These estimates are more precisely estimated and of smaller magnitude than those presented by the previous studies. The results are robust to the different specifications of the wage equation. The simulation analysis based on the predicted values shows that about 17% of the change in the second birth hazard over the period 1980 to 2005 was due to the change in the female wage. Although there is some limitation in data, the results can be viewed as one estimate of the role of female wage on the recent fertility decline in Korea. The question raised by the paper is not a normative one of whether a government should promote childbearing but a positive one thatexplains fertility decline. Therefore, if there is a wide consensus on promoting childbearing, the finding suggests that the policies designed to reduce the opportunity cost of women in the labor market would be effective. The recent movement of implementing a wide range of family-friendly policies including child care support, maternity leave, parental leave and tax benefit in developed countries should be understood in this context.

  • PDF

Numerical Test for the 2D Q Tomography Inversion Based on the Stochastic Ground-motion Model (추계학적 지진동모델에 기반한 2D Q 토모그래피 수치모델 역산)

  • Yun, Kwan-Hee;Suh, Jung-Hee
    • Geophysics and Geophysical Exploration
    • /
    • v.10 no.3
    • /
    • pp.191-202
    • /
    • 2007
  • To identify the detailed attenuation structure in the southern Korean Peninsula, a numerical test was conducted for the Q tomography inversion to be applied to the accumulated dataset until 2005. In particular, the stochastic pointsource ground-motion model (STGM model; Boore, 2003) was adopted for the 2D Q tomography inversion for direct application to simulating the strong ground-motion. Simultaneous inversion of the STGM model parameters with a regional single Q model was performed to evaluate the source and site effects which were necessary to generate an artificial dataset for the numerical test. The artificial dataset consists of simulated Fourier spectra that resemble the real data in the magnitude-distance-frequency-error distribution except replacement of the regional single Q model with a checkerboard type of high and low values of laterally varying Q models. The total number of Q blocks used for the checkerboard test was 75 (grid size of $35{\times}44km^2$ for Q blocks); Q functional form of $Q_0f^{\eta}$ ($Q_0$=100 or 500, 0.0 < ${\eta}$ < 1.0) was assigned to each Q block for the checkerboard test. The checkerboard test has been implemented in three steps. At the first step, the initial values of Q-values for 75 blocks were estimated. At the second step, the site amplification function was estimated by using the initial guess of A(f) which is the mean site amplification functions (Yun and Suh, 2007) for the site class. The last step is to invert the tomographic Q-values of 75 blocks based on the results of the first and second steps. As a result of the checkerboard test, it was demonstrated that Q-values could be robustly estimated by using the 2D Q tomography inversion method even in the presence of perturbed source and site effects from the true input model.

Generation of a transgenic mouse model to study cranial suture development; Apert syndrome (두개봉합 발육 연구를 위한 형질변환 쥐의 개발 : 어퍼트 신드롬)

  • Lee, Kee-Joon;Ratisoontorn, Chootima;Baik, Hyoung-Seon;Park, Young-Chel;Park, Kwang-Kyun;Nah, Hyun-Duck
    • The korean journal of orthodontics
    • /
    • v.33 no.6 s.101
    • /
    • pp.485-497
    • /
    • 2003
  • The form and function of the craniofacial structure critically depend on genetic information. With recent advances in the molecular technology, genes that are important for normal growth and morphogenesis of the craniofacial skeleton are being rapidly uncovered, shaping up modem craniofacial biology. One of them is fibroblast growth factor receptor 2 (FGFR2). Specific point mutations in the. FGFR2 gene have been linked to Apert syndrome, which is characterized by premature closure of cranial sutures and craniofacial anomalies as well as limb deformities. To study pathogenic mechanisms underlying craniosynostosis phenotype of Apert syndrome, we used a transgenic approach; an FGFR2 minigene construct containing an Apert mutation (a point mutation that substitute proline at the position 253 to arginine; P253R) was introduced into fertilized mouse germ cells by DNA microinjection. The injected cells were then allowed to develop into transgenic mice. We used a bone-specific promoter (a DNA fragment from the type I collagen gene) to confine the expression of mutant FGFR2 gene to the bone tissue, and asked whether expression of mutant FGFR2 in bone is sufficient to cause the craniosynostosis phenotype in mice. Initial characterization of these mice shows prematurely closed cranial sutures with facial deformities expected from Apert patients. We also demonstrate that the transgene produces mutant FGFR2 protein with increased functional activities. Having this useful mouse model, we now can ask questions regarding the role of FGFR2 in normal and abnormal development of cranial bones and sutures.

The Morpho-Imaganary Viewpoints of Lee Je-ma and the Morpho-Imaganary recognitions of Sasang Constitutional Medicine (동무공(東武公)의 형상관(形象觀)과 사상의학(四象醫學)의 형상의학정신(形象醫學精神))

  • Song, Il-byung
    • Journal of Sasang Constitutional Medicine
    • /
    • v.11 no.1
    • /
    • pp.1-13
    • /
    • 1999
  • Lee Je-ma created Sasang Constitutional Medicine from the insight of different congenital formation of Viscera which was based on his own Morpho-Imaganary recognition of human beings. The basic principles to understand human beings are as follows. The first, human beings are morphologically figured based on the human nature. The Second, Morpho-lmaganary recognition was the understanding to all the things including human with the rule of society and the relationships. affairs-mind-body-objects. The Morpho-Imaganary characteristics of Sasang Constitutional Medicine are as follows. The first, Sasang Constitutional Medicine recognize the symptoms and diseases as the aspect of structure and function at the same time. The second, it recognize the symptoms and diseases with the viewpoint of Change.

  • PDF

Microwave Dielectric Properties of (${Pb_{0.2}}{Ca_{0.8}}$)[$({Ca_{1/3}}{Nb_{2/3}})_{1-x}{Ti_x}$]$O_3$ Ceramics (Microwave Dielectric Properties of (${Pb_{0.2}}{Ca_{0.8}}$)[$({Ca_{1/3}}{Nb_{2/3}})_{1-x}{Ti_x}$$O_3$ 세라믹스의 마이크로파 유전특성)

  • Kim, Eung-Soo;Kim, Yong-Hyun;Kim, Jun-Chul;Bang, Kyu-Seok
    • Korean Journal of Materials Research
    • /
    • v.11 no.8
    • /
    • pp.708-712
    • /
    • 2001
  • Microwave dielectric properties of $(Pb_{0.2}Ca_{0.8})[(Ca_{1/3}Nb{2/3})_{1-x}Ti_x]O_3$ ceramics were investigated as a function of $Ti^{4+}$ content (0.05$\leq$x$\leq$0.35). A single perovskite phase was obtained from x=0.05 to x=0.15, and $TiO_2$ and $CaNb_2O^6$ were detected as a secondary phase beyond x=0.2. The structure was changed from orthorhombic at x=0.05 to cubic at x=0.35. Dielectric constant(K) was increased with increase of $Ti^{4+}$ content due to increase of rattling effect, and was inversely proportional to the cube of the average radius of B-site cation, however, Qf value was decreased, which was due to the decrease of grain size and the secondary phase. With the increase of $Ti^{4+}$ content, the temperature coefficient of resonant frequency(TCF) was controlled from -27.36 ppm/$^{\circ}C$ value to +18.4 ppm/$^{\circ}C$ value, which was caused by the influence of tolerance factor(t) and the bond valence of B-site. Typically, K of 51.67, Qf of 7268(GHz), TCF of 0 ppm/$^{\circ}C$ were obtained in the $(Pb_{0.2}Ca_{0.8})[(Ca_{1/3}Nb_{2/3})_{0.8}Ti_0.2]O_3$ sintered at 13$50^{\circ}C$ for 3h.

  • PDF

Discounted Cost Model of Condition-Based Maintenance Regarding Cumulative Damage of Armor Units of Rubble-Mound Breakwaters as a Discrete-Time Stochastic Process (경사제 피복재의 누적피해를 이산시간 확률과정으로 고려한 조건기반 유지관리의 할인비용모형)

  • Lee, Cheol-Eung;Park, Dong-Heon
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.29 no.2
    • /
    • pp.109-120
    • /
    • 2017
  • A discounted cost model for preventive maintenance of armor units of rubble-mound breakwaters is mathematically derived by combining the deterioration model based on a discrete-time stochastic process of shock occurrence with the cost model of renewal process together. The discounted cost model of condition-based maintenance proposed in this paper can take into account the nonlinearity of cumulative damage process as well as the discounting effect of cost. By comparing the present results with the previous other results, the verification is carried out satisfactorily. In addition, it is known from the sensitivity analysis on variables related to the model that the more often preventive maintenance should be implemented, the more crucial the level of importance of system is. However, the tendency is shown in reverse as the interest rate is increased. Meanwhile, the present model has been applied to the armor units of rubble-mound breakwaters. The parameters of damage intensity function have been estimated through the time-dependent prediction of the expected cumulative damage level obtained from the sample path method. In particular, it is confirmed that the shock occurrences can be considered to be a discrete-time stochastic process by investigating the effects of uncertainty of the shock occurrences on the expected cumulative damage level with homogeneous Poisson process and doubly stochastic Poisson process that are the continuous-time stochastic processes. It can be also seen that the stochastic process of cumulative damage would depend directly on the design conditions, thus the preventive maintenance would be varied due to those. Finally, the optimal periods and scale for the preventive maintenance of armor units of rubble-mound breakwaters can be quantitatively determined with the failure limits, the levels of importance of structure, and the interest rates.

An Interpretation of the Folktale 'the Servant Who Ruined the Master's House' from the Perspective of Analytical Psychology: Centering on the Trickster Archetype (민담 '주인집을 망하게 한 하인'의 분석심리학적 이해: 트릭스터 원형을 중심으로)

  • Myoungsun Roh
    • Sim-seong Yeon-gu
    • /
    • v.37 no.2
    • /
    • pp.184-254
    • /
    • 2022
  • Through this thesis, the psychological meaning of the Korean folktale 'the servant who ruined the master's house' was examined. The opposition between the master and the servant is a universal matter of the human psychology. It can be seen as a conflict between the hardened existing collective consciousness and the new consciousness to compensate for and renew it. From different angles, it has become the opposition between man's spiritual and instinctive aspects, between the conscious and the unconscious, or between the ego and the shadow. In the folktale, the master tries several times to get rid of the youngest servant, but the servant uses tricks and wits to steal food, a horse, the youngest sister, and all money from the master, and finally, take his life. It ends with the marriage of the youngest sister and the servant. Enantiodromia, in which the master dies, and the servant becomes the new master, can be seen that the old collective consciousness is destroyed, and the new consciousness that has risen from the collective unconscious takes the dominant position. In an individual's psychological situation, it can be seen that the existing attitude of the ego is dissolved and transformed into a new attitude. In the middle of the story, the servant marries the youngest sister by exploiting naive people to rewrite the back letter written by the master to kill him. This aspect can be understood negatively in the moral concept of collective consciousness, but it can also be seen as a process of integrating mental elements that have been ignored in the collective consciousness of the Joseon Dynasty, symbolized by a woman, a honey seller, and a hungry Buddhist monk. The new consciousness, represented by the servant, has the characteristics of a trickster that is not bound by the existing frame, so it can encompass the psychological elements that have been ignored in the collective consciousness. Such element may represent compensation or an alternative to the collective consciousness in the late Joseon Dynasty. The master puts the servant in a leather bag and hangs it on a tree to kill the servant. However, the servant deceives a blind man; he opened his eyes while hanged. Instead of the servant, the blind man dies, and the servant is freed. As the problem of the conflict between master and servant is finally entrusted to the whole spirit (Self) symbolized by a tree, the blind man gets removed. It can be understood as an intention of the Self to distinguish and purify the elements of recklessness, stupidity, and greed included in the trickster. Through these processes, the servant, which symbolizes a new change in collective consciousness or a new attitude of ego, solves the existing problems and takes the place of the master. While listening to the cunning servant's performance, the audience feels a sense of joy and liberation. At the same time, in the part where the blind man and the master's family die instead and the servant becomes the master, they experience feelings of fear and concern about the danger and uncontrollability of the servant. The tricksters appearing in foreign analogies are also thoroughly selfish and make innocent beings deceive or die in order to satisfy their desires and escape from danger. Efforts to punish or reform these tricksters are futile and they run away. Therefore, this folktale can also be seen as having a purpose and meaning to let us know that this archetypal shadow is very dangerous and that consciousness cannot control or assimilate it, but only awe and contemplate it. Trickster is an irrational manifestation of revivifying natural energy that rises from the unconscious as a compensation for hardened existing structure and order. The phenomenon may be destructive and immoral from the standpoint of the existing collective mind, but it should be seen as a function of the collective unconscious, a more fundamental psychic function that cannot be morally defined. The servant, a figure of the trickster archetype, is a being that brings transformation and has the duality and contradiction of destructiveness and creativity. The endings of this folktale's analogies are diverse, reflecting the diversified response of the audience's mind due to the ambivalence of the trickster, and also suggesting various responses toward the problem of the trickster from the unconscious. It also shows that the trickster is a problem of inconclusive and controversial contradictions that cannot be controlled with a conscious rational attitude, and that we can only seriously contemplate the trickster archetype within us.

A Study on medical Qigong mentioned in ${\ll}$Samilshingo${\gg}$ (三一神誥) (${\ll}$삼일신고(三一神誥)${\gg}$에 나타난 의료기공(醫療氣功)에 관(關)한 연구(硏究))

  • Ban, Chang-Yul
    • Journal of Korean Medical Ki-Gong Academy
    • /
    • v.7 no.2
    • /
    • pp.40-94
    • /
    • 2004
  • Recently, meditation, Zen meditation and Qigong became popular in western. For that reason, Value of Korea traditional methods for health promotion have been evaluated but theoretical evidence about that is insufficient. ${\ll}$The Yellow Emperor's Inner Classic${\gg}$ (黃帝內經). So, I reviewed history of Korea Qigong according to period, in order to produce theoretical evidence of Korea medical Qigong and investigated ${\ulcorner}$Han${\lrcorner}$ thought (${\ulcorner}$${\lrcorner}$ 思想) as theoretical evidence of Korea Qigong. I have obtained following results by comparing meaning of god, a view of human body and practice method of the ${\ll}$Samilshingo${\gg}$ (三一神誥) with ${\ll}$The Yellow Emperor's Inner Classic${\gg}$ (黃帝內經). Sinsundo(神仙道) of native to race became active during the period of the Three Kingdoms but more disappeared due to under the influence of Taoism. So only has been remained in existence since the period of the unity silla. There could accept positively the foreign ideas belonging to Confucianism, Buddhism and Taoism have been brought since the period of the Three Kingdoms because ${\ll}$Samilshingo${\gg}$ (三一神誥), one of three the scriptures as the origin of ${\ulcorner}$Han${\lrcorner}$ thought(${\ulcorner}$${\lrcorner}$ 思想) included the original form of three religion belonging to Confucianism, Buddhism, Taoism. Three common results as theoretical evidence of Qigong were found out by comparing ${\ll}$Samilshingo${\gg}$ (三一神誥) with ${\ll}$The Yellow Emperor's Inner Classic${\gg}$ (黃帝內經). First, in meaning of god, there is not only different from the gods of heaven and the gods of human but also keep understanding with each other and there was common feature of logical structure that function of god was divided into three. Second, In a view of human body, there were in common with ${\ll}$Samilshingo${\gg}$ (三一神誥) as theory of only as energy(氣一元論), theory of bisection as truth false(眞妄二分論), theory of trisection as spirit(性) destiny(命) nature(精) and mind(心) energy(氣) body(身)(性 命 精, 心 氣 身의 三分論) and ${\ll}$The Yellow Emperor's Inner Classic${\gg}$ (黃帝內經) as theory of only as energy(氣一元論), theory of bisection as shape and god(形神二分論), theory of trisection as nature(精) energy(氣) god(神) or shape(形) energy(氣) god(神)(精 氣 神, 形 氣 神의 三分論) according to formal part. Also, spirit(性) destiny(命) nature(精) as truths of three(三眞) were understand as nature(精) energy(氣) god(神) as treasure of three(三寶) by part of reason and mind(心) energy(氣) body(身) as false of three(三妄) were understand as nature(精) energy(氣) god(神) as treasure of three(三寶) by part of function. Third, In practice method, pause of thinking(止感) modulation of breath(調息). prohibition of sensibility(禁觸) mentioned in ${\ll}$Samilshingo${\gg}$ (三一神誥) as practice method each were understand regulation of an etiological cause as an internal cause, an external cause and not internal and external cause in oriental medicine. Namely, pause of thinking(止感) was understand as regulation method of emotion, mind and nature. modulation of breath(調息) was not only as modulation of energy from the inner parts of the body but also that from the internal and external parts of the body, prohibition of sensibility(禁觸) was understand as regulation method of ear, eye, mouth, and nose and posture, life style. These results suggest that ${\ll}$Samilshingo${\gg}$ (三一神誥) is worth meaning of Korea medical Qigong because meaning of god, a view of human body, practice method of mentioned in ${\ll}$Samilshingo${\gg}$ (三一神誥) is common with that of ${\ll}$The Yellow Emperor's Inner Classic${\gg}$ (黃帝內經) as theoretical evidence of Qigong.

A Study on Modern People's Consciousness and Wearing Practice of Korean Costumes (우리나라 옷에 대한 현대인(現代人)의 의식(意識)과 춘용실태(春用實態)에 관(關)한 연구(硏究) - 서울 지역(地域)을 중심(中心)으로 -)

  • Hwang, Chun-Sub
    • Journal of the Korean Society of Costume
    • /
    • v.1
    • /
    • pp.119-129
    • /
    • 1977
  • It is significant for developing the future for us to know our present age. In order to preserve our Korean costume as a fola clothes retaining our distinguished independent characterisitics and to help design the tomorrow of our Korean costume playing a role as a racial to develop the world clothing culture, a survey was conducted to investigate modern people's conscious-ness and wearing practumes of Korean costume by questionaire and interviewing methods. The results of the survey were analyzed as follows: (1) At present, Korean costumes were purchased as customtailored(64.0%) and as ready-made(17.8%) and most of them were not made at individual homes. The laundry and ironing of them were carried out at laundry shops(68.8%). Considering our present economic, social and cultural aspects, sowing, laundryand ironing will not be carried out at homes again in the future and ready made costumes seen to be produced in a large scale in the future. Garment makers and laundry shop operators should be trained how to make our Korean costumes retain our traditional beauty in the course of their production and laundry and the makers of ready-made costumes must make research how to efficiently produce ideal ready-made costumes by adopting the synchro system in their wrk odisivion. (2) The age group wearing Korean costumes most frequently was the aged people over 60 (their wearing rate; 45%-50%) and the group wearing them most frequently next io the aged people over 60, was housewives(their wearing rate; 15%-20%). Excludign aged people and housewives, other respondentsdid not wear Korean costumes very frequently. Men's wearing rate was lower their wearing rate was the younger their ages were and the less their monthly incomes were. Korean costumes were used for holiday and festival(60%), wedding and funeral ceremonies (52%), visiting and working(22%), casual wear(12.8%) and home wear(9.2%). The use of Korean costumes as casual and home wears, was lower than the use for holday, festival, visiting and working, Under our present circumstances in which our Korean people use both Western style clothes and Korean costumer, our Korean costume has lostits position as a basic and necessary requiement in Korean people's daily life and become a ceremonical and fancy costume. It is natural that the times and life change everything in our daily life. Our costume has to be made as good ceremonial and fancy clothes satisfying modern sensibility according to its new role. In order for us to get close with our clothes, a keen study must be carried out to cleat the color, material, style, function and harmony of the Korean costume matching the of the times. (3) The 47.8% of the respondents answered that they were proud of our Korean costume as our folk clothes, 47.6% replied that thought them just common and 1.1% responded that they were ashamed of it. Most of them were affirmative in feeling pride with our Korean costume. (4) Considering the functional aspect of Korean costumes, their strong points were symetric beauty, rhythmical beauty, unity feeling, harmonical beauty and detailed decorations. Their common shortcomings were lack of individuality and inadequateness for active life. The shortcomings of woman costumes were suppressing breast, making resperation difficult and in adequnteness in summer time. The main reason not to wear our Korean costumes, was due to the fact that they are incomvenient for active life. As a measure to eliminate such shortcomings, 1) the suspension system of skirt to remove the suppression of breast should be generally adopted. 2) they should be simplified in their structure to make them convenient for active life and adepuate in wearing them in hot weather in an extent to which the traditional beauty of the costume may not be lostand 3) a new technique must be explored for showing individuality by wearing method and new arrangment of colors and decorations. (5) The reasons desiring to wear Korean costumes were classifide as follows: A. Korean costumes are our traditional clothes(43.4%). B. Korean costumes are noble and beautiful(26.8%). C. They are accustomed to wear Korean costumes by habit(19.5%). D. Korean costumes are necessary for attending ceremoneis(9.5%). E. Miscellaneous reasons(0.8%). Classifying these reasons into age groups, the high age group over 40 wore them because they were easy to wear by habit and the low age group of 10-30 never thought that they were east to wear by habit. Considering that even those who were accustomed to wear Korean costumes showed a low wearing rate and that the young generation were accustomed to wear Western style clothes rather than Korean costumes, the wearing rate of Korean costumes will be reduced in the future if such trend continues. It is urgent for us to make our best efforts in order to enhance the interest of young generation in Korean costumes and not to make them lose the strong points of Korean costume in the future. (6) Conicering the plan of the respondents on what kind of clothes they were going to wear in the future, among the age group over 50, those who wanted to wear only Korean costumes were 24.8%(men) and 35.1%(women), those who wanted to wear 49.7%(men) and 47.4(women), those who wanted to wear chiefly Western style clothes were 20.7% (men) and 14.4%(women) and those who wanted to wear only Western style clothes, were 2.4% (men) and 2.1%(women). This shows that the general tendency to wear only or chiefly Korean costumes is more prevalent than that to wear only Western style. Among the age group under 50, the tendency to wear Western style clothes was conspicuous and most of the respondent answered that they would wear chiefly Western style clothes and Korean costumes occasionally. Only 5.4% of the respondent answered that they would wear only Western style clothes and this shows that meny respondents still wonted to wear Korean costumes. Those who wanted their descendants to wear what they desire, were 50.1%(men) and 68.8% (women) and those who wanted their descendants to wear Koran costumes occasionally, were 85.8%(men) and 86.3%(women). This shows that most of respondents wanted their descendants to wear Korean costumes. In order to realize, it is necessory for us to make ourdescendants recognize the preciousness of our traditional culture and modify our Korean costumes according to their taste so that they may like wearing them.

  • PDF

Evaluation of Cryptosporidiurn Disinfection by Ozone and Ultraviolet Irradiation Using Viability and Infectivity Assays (크립토스포리디움의 활성/감염성 판별법을 이용한 오존 및 자외선 소독능 평가)

  • Park Sang-Jung;Cho Min;Yoon Je-Yong;Jun Yong-Sung;Rim Yeon-Taek;Jin Ing-Nyol;Chung Hyen-Mi
    • Journal of Life Science
    • /
    • v.16 no.3 s.76
    • /
    • pp.534-539
    • /
    • 2006
  • In the ozone disinfection unit process of a piston type batch reactor with continuous ozone analysis using a flow injection analysis (FIA) system, the CT values for 1 log inactivation of Cryptosporidium parvum by viability assays of DAPI/PI and excystation were $1.8{\sim}2.2\;mg/L{\cdot}min$ at $25^{\circ}C$ and $9.1mg/L{\cdot}min$ at $5^{\circ}C$, respectively. At the low temperature, ozone requirement rises $4{\sim}5$ times higher in order to achieve the same level of disinfection at room temperature. In a 40 L scale pilot plant with continuous flow and constant 5 minutes retention time, disinfection effects were evaluated using excystation, DAPI/PI, and cell infection method at the same time. About 0.2 log inactivation of Cryptosporidium by DAPI/PI and excystation assay, and 1.2 log inactivation by cell infectivity assay were estimated, respectively, at the CT value of about $8mg/L{\cdot}min$. The difference between DAPI/PI and excystation assay was not significant in evaluating CT values of Cryptosporidium by ozone in both experiment of the piston and the pilot reactors. However, there was significant difference between viability assay based on the intact cell wall structure and function and infectivity assay based on the developing oocysts to sporozoites and merozoites in the pilot study. The stage of development should be more sensitive to ozone oxidation than cell wall intactness of oocysts. The difference of CT values estimated by viability assay between two studies may partly come from underestimation of the residual ozone concentration due to the manual monitoring in the pilot study, or the difference of the reactor scale (50 mL vs 40 L) and types (batch vs continuous). Adequate If value to disinfect 1 and 2 log scale of Cryptosporidium in UV irradiation process was 25 $mWs/cm^2$ and 50 $mWs/cm^2$, respectively, at $25^{\circ}C$ by DAPI/PI. At $5^{\circ}C$, 40 $mWs/cm^2$ was required for disinfecting 1 log Cryptosporidium, and 80 $mWs/cm^2$ for disinfecting 2 log Cryptosporidium. It was thought that about 60% increase of If value requirement to compensate for the $20^{\circ}C$ decrease in temperature was due to the low voltage low output lamp letting weaker UV rays occur at lower temperatures.