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After the COVID-19 Pandemic, New Tasks and Directions of Christian Education in Korean Churches (코로나 팬데믹 이후 한국교회 기독교교육의 19 새로운 과제와 방향)

  • Jeong Joon Kim
    • Journal of Christian Education in Korea
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    • v.78
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    • pp.21-55
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    • 2024
  • Purpose of study: The purpose of this study is to examine the crisis situation of Christian education experienced by Korean churches and theological education institutions after the COVID-19 pandemic, and to seek new tasks and directions that Korean churches should prepare for the recovery and growth of Christian education. Research Contents and Methods: Before reviewing the current crisis experienced by Korean churches and theological education institutions after the COVID-19 pandemic, the terms and concepts of Christian education are first reflected. In addition, the causes and phenomena of the Korean church and Christian education crisis after the COVID-19 Pandemic are examined through statistics, media, and church field data. The researcher identified the causes of the crisis experienced by Korean churches and theological education institutions as follows: 1. The influence of COVID-19 Pandemic: suspension of faith and educational activities, 2. The age of population cliffs: increase in the elderly vs. decrease in young people, 3. Neoliberalism: marketism, infinite competition, efficiency, winner-take-all, 4. post-religious era: post-Christianity, weakened communitarianism, and reduced number of Christians. The results of this study are four points as follows: 1. Crisis of church education: suspension of operation of Sunday school and feeling of failure, 2. Crisis of faith of young generation: nurturing unstable future church leaders, 3. Faith of adult generation: crisis and hope, 4. The faith of the elderly generation: light and shadow. Conclusion and Recommendations: The new task and direction of Christian education that Korean churches should pursue after the COVID-19 pandemic are as follows: 1. New conversion of Sunday school faith education: From schooling-paradigm education to faith education that integrates family and generation. 2. New conversion of theological education: From knowledge education to spirituality training. 3. Re-ignition of faith education for middle-aged adults: Activation of faith through worship and small groups, 4. New conversion of church elder education: The need to change from caring objects to creative religious life.

Emulsion Liquid Membrane Transport of Heavy Metal Sons by Macrocyclic Carriers (거대고리 운반체에 의한 중금속이온의 에멀죤 액체막 수송)

  • 정오진
    • Journal of Environmental Science International
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    • v.4 no.2
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    • pp.223-232
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    • 1995
  • New two macrocyclic compounds using as carriers of liquid emulsion menbrame, have been synthesized. These reuslts provide evidance for the usefulness of the theory in designing the systems. The efficiency of selective transport for heavy metal ions have been discussed from the membrane systems that make use of $SCN^-$,<>,$I^-$,CN- and $Cl^-$ ion as co-anions in source phase and make use of $S_2O_3^{2-}$ and $P_2O_7^{4-}$ ion as receiving phase, respectively. The transport rate of M(II) was highest when a maximum amount of the M(II) in the source phase was present as$Cd(SCN)_2$$(P[SCN^-]= 0.40M)$, $Hg(SCN)_2([SCN^-]=0.40M)$ and Pd(CN)$([CN^-]= 0.40M)$. The Cd(II) and Pb(II) over each competitive cations were well transprted with 0.3M-S2032- and 0.3M-P2O74-, respectively in the receiving phase. Results of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsion system. First one must effective extraction of the $M^{n+}$ into the toluene systems. The effectiveness of this extraction is the greatest if locK for $M^{n+}$macrocycle interaction is large and if the macrocycle is very insoluble in the aqueous phase. Second, the ratio of the locK values (or Mn+-receiving phase ($S_2O_3^{2-}$- or $P_2O_7^{4-}$) to $M^{n+}$-macrocycle (($L_1$이나 $L_2$) interaction must be large enough to ensure quantitative stripping of Mn+(($Cd^{2+}$,$Pb^{2+}$)at the toluene receiving Phase interface. $L_1$(3.5-benzo-10,13,18,21-tetraoxa-1,7,diazabicyclo(8,5,5) eicosan) forms a stable ($Cd^{2+}$ and >,$Pb^{2+}$ complexes and $L_1$ is very insoluble in water and its $Cd^{2+}$ and >,$Pb^{2+}$ complex is considerably less stable than $Cd^{2+}$-(S2O3)22- and $Pd^{2+}-P_2O_7^{4-}$ complexes. On the other hand, the stability of the $Hg^{2+}$)+-$L_1$( complex exceed that of the $Hg^{2+}$- (S2O3)22- and Hg2+-P2O74-, and the distribution coefficient of $L_2$(5,8,15,18,23,26-hexaoxa-1,12- diazabicyclo-(10,8,8) octacosane) is much smaller than that of $L_1$. Therefore, the partitioning of Lr is favored by the aqueous receiving Phase, and little heavy metal ions transport is seen despite the large logK for $Hg^{2+}$+-$L_1$ and $Mn^+$($Cd^{2+}$+, $Pb^{2+}$+ and $Hg^{2+}$)-$L_2$ interactions. Key Words : macrocycles, transport, heavy metal, co-anion, source phase, receiveing, complex separation, interaction, destribution coefficient.

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CAS 500-1/2 Image Utilization Technology and System Development: Achievement and Contribution (국토위성정보 활용기술 및 운영시스템 개발: 성과 및 의의)

  • Yoon, Sung-Joo;Son, Jonghwan;Park, Hyeongjun;Seo, Junghoon;Lee, Yoojin;Ban, Seunghwan;Choi, Jae-Seung;Kim, Byung-Guk;Lee, Hyun jik;Lee, Kyu-sung;Kweon, Ki-Eok;Lee, Kye-Dong;Jung, Hyung-sup;Choung, Yun-Jae;Choi, Hyun;Koo, Daesung;Choi, Myungjin;Shin, Yunsoo;Choi, Jaewan;Eo, Yang-Dam;Jeong, Jong-chul;Han, Youkyung;Oh, Jaehong;Rhee, Sooahm;Chang, Eunmi;Kim, Taejung
    • Korean Journal of Remote Sensing
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    • v.36 no.5_2
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    • pp.867-879
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    • 2020
  • As the era of space technology utilization is approaching, the launch of CAS (Compact Advanced Satellite) 500-1/2 satellites is scheduled during 2021 for acquisition of high-resolution images. Accordingly, the increase of image usability and processing efficiency has been emphasized as key design concepts of the CAS 500-1/2 ground station. In this regard, "CAS 500-1/2 Image Acquisition and Utilization Technology Development" project has been carried out to develop core technologies and processing systems for CAS 500-1/2 data collecting, processing, managing and distributing. In this paper, we introduce the results of the above project. We developed an operation system to generate precision images automatically with GCP (Ground Control Point) chip DB (Database) and DEM (Digital Elevation Model) DB over the entire Korean peninsula. We also developed the system to produce ortho-rectified images indexed to 1:5,000 map grids, and hence set a foundation for ARD (Analysis Ready Data)system. In addition, we linked various application software to the operation system and systematically produce mosaic images, DSM (Digital Surface Model)/DTM (Digital Terrain Model), spatial feature thematic map, and change detection thematic map. The major contribution of the developed system and technologies includes that precision images are to be automatically generated using GCP chip DB for the first time in Korea and the various utilization product technologies incorporated into the operation system of a satellite ground station. The developed operation system has been installed on Korea Land Observation Satellite Information Center of the NGII (National Geographic Information Institute). We expect the system to contribute greatly to the center's work and provide a standard for future ground station systems of earth observation satellites.

Removal Characteristics of Residual Hydrogen Peroxide (H2O2) according to Application of Peroxone Process in O3/BAC Process (O3/BAC 공정에서 Peroxone 공정 적용에 따른 잔류 과산화수소 제거 특성)

  • Yeom, Hoon-Sik;Son, Hee-Jong;Seo, Chang-Dong;Kim, Sang-Goo;Ryu, Dong-Choon
    • Journal of Korean Society of Environmental Engineers
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    • v.35 no.12
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    • pp.889-896
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    • 2013
  • Advanced Oxidation Processes (AOP) have been interested for removing micropollutants in water. Most of water treatment plants (WTPs) located along the lower part of Nakdong River have adopted the $O_3/BAC$ process and have interesting in peroxone process a kind of AOP. This study evaluated the removal characteristics of residual hydrogen peroxide ($H_2O_2$) combining with the biofiltration process in the next BAC process when the hydrogen peroxide is applied for the WTP operating $O_3/BAC$ process. In the experiment, changing the temperature and the concentration of $H_2O_2$ of influent, the biofiltration process showed rapidly dropped the biodegradability when the $H_2O_2$ concentration was increased and lowered water temperature while BAC process maintained relatively stable efficiency. The influent fixed at $20^{\circ}C$ and the concentration of $H_2O_2$ at 300 mg/L was continuously input for 78 hours. Most of the $H_2O_2$ in the influent did not remove at the biofiltration process controlled 5 to 15 minutes EBCT condition after 24~71 hours operating time while BAC process controlled 5 to 15 minutes EBCT showed 38~91% removal efficiency condition after 78 hours operating time. Besides, after 78 hours continuously input experiment, the biomass and activity of attached bacterial on the biofilter and BAC were $6.0{\times}10^4CFU/g$, $0.54mg{\cdot}C/m^3{\cdot}hr$ and $0.4{\times}10^8CFU/g$, $1.42mg{\cdot}C/m^3{\cdot}hr$ respectively. These biomass and activity values were decreased 99% and 72% in biofilter and 68% and 53% in BAC compared with initial condition. The biodegradation rate constant ($k_{bio}$) and half-life ($t_{1/2}$) in BAC were decreased from $1.173min^{-1}$ to $0.183min^{-1}$ and 0.591 min to 3.787 min respectively according to increasing the $H_2O_2$ concentration from 10 mg/L to 300 mg/L at $5^{\circ}C$ water temperature and the $k_{bio}$ and $t_{1/2}$ were $1.510min^{-1}$ to $0.498min^{-1}$ and 0.459 min to 1.392 min at $25^{\circ}C$ water temperature. By increasing the water temperature from $5^{\circ}C$ to $15^{\circ}C$ or $25^{\circ}C$, the $k_{bio}$ were increased 1.1~2.1 times and 1.3~4.4 times. If a water treatment plant operating $O_3/BAC$ process is considering the hydrogen peroxide for the peroxone process, post BAC could effectively decrease the residual $H_2O_2$, moreover, in case of spilling the $H_2O_2$ into the water process line, these spilled $H_2O_2$ concentration can be able to decrease by increasing the EBCT at the BAC process.

Growth and Yield Characteristics of Foxtail Millet, Comon Millet Cereal Crops on Marginal Agricultural Lands (조건 불리 한계농경지에서의 조, 수수, 기장의 생육 및 수량)

  • Yoon, Seong-Tak;Lee, Myung-Cheol;Kim, Jeong-Soon;Zhang, Qingyu;Xu, Zhen-Yu;Kim, Young-Bok;Kim, Tae-Ho;Nam, Jung-Chang;Nam, Min-Hee;Lee, Young-Hawn;Hwang, Jae-Bok;Shim, Sang-In;Kim, Seong-Min
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.55 no.4
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    • pp.350-356
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    • 2010
  • This experiment was conducted to select optimum minor cereal crop and variety for the marginal agricultural lands so that they would be used to increase the agricultural land use rate in mountainous areas. This experiment used three different marginal agricultural lands, that is, slope land, barren land and gravelly land. Soil pH of control field was 7.85, slightly alkali, whereas gravelly land showed strong acid(pH 5.1). EC of marginal agricultural lands was generally lower compared to the control, especially barren land showed 0.05dS $m^{-1}$ which was the lowest among marginal agricultural lands. Foxtail millet showed no significant difference of heading and ripening date among marginal agricultural lands. Foxtail millet of slope land showed the highest culm length(169.5 cm) and grains per ear(4913.9 grains) among marginal agricultural lands except control field. Growth duration of three varieties was varied from 112 to 113days, which was not different statistically. In grains per ear of common millet, slope land showed 787.1 grains which was the highest among marginal agricultural lands except control field. Among varieties, Byorukgijang showed the highest grains per ear(827.2 g/ear), whereas 1000 grain weight was 5.5 g which was lower compared to that of Hwanggijang(6.2 g). In sorghum, slope land showed the highest grains(2563.8 grains) per ear and ears per 3.3 $m^2$(26.0 ears) except control field. Growth duration of three sorghum varieties almost the same from 122 to 123 days, whereas the highest grains per ear was obtained from Moktaksusu(2357.6 grains). Jangmoksusu showed the highest 1000 grain weight(23.8 g) among three sorghum varieties. In yield of three foxtail millets, the highest yield was obtained from slope land(282.0 kg/10a) among marginal agricultural lands and Mongdangjo showed the highest yield(252.3 kg/10a) among three varieties. In yield of three common millets, the highest yield was obtained from slope land(196.0 kg/10a) among marginal agricultural lands and Byorukgijang showed the highest yield(173.8 kg/10a) in three varieties. In three sorghum varieties, the highest yield was obtained from slope land(301.7 kg/10a) among marginal agricultural lands and Moktaksusu showed the highest yield(236.5 kg/10a) among three varieties.

Effects on the Rumen Microbial Fermentation Characteristics of Lignosulfonate Treated Soybean Meal (Lignosulfonate처리 대두박의 반추위 내 미생물 발효특성에 미치는 영향)

  • Lee, Hun-Jong;Lee, Seung-Heon;Bae, Gui-Seck;Park, Je-Hwan;Chang, Moon-Baek
    • Journal of Animal Science and Technology
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    • v.52 no.5
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    • pp.413-426
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    • 2010
  • This study was conducted to investigate the effects on fermentation characteristics of rumen microorganism by different types and levels of lignosulfonate treated soybean meal (LSBM) in in vitro test and rumen simulation continuous culture (RSCC) system in dairy cows. The experiment I was control and 12 treatments (each with 3 replications) in vitro test to demonstrate composition of different types of treatments with lignosulfonate (Desulfonate, Na, Ca and solution) and levels (2, 4 and 8%) of soybean meal in the dairy cow diet. LSBM source treatments in the dairy cow diet showed pH value, $NH_3$-N concentration and total VFA concentration lower than control at all levels and incubation times (p<0.05). Dry matter digestibility of LSBM source treatments showed lower than control (p<0.05). Gas production and rumen microbial synthesis was decreased by rumen microbial fermentation for incubation times. Undegradable protein (UDP) concentration of all LSBM treatments was decreased for incubation times, and significantly higher than control (p<0.05). In the experiment II compared diets of the control, LSBM Na 2%, LSBM Sol 2%, which are high performance to undegradable protein (UDP) concentration experiment I in vitro test, and heated treatment lignosulfonate (LSBM Heat) 2% in the dairy cow diet from four station RSCC system ($4{\times}4$ Latin square). A rumen microbial fermentation characteristic was stability during 12~15 days of experimental period in all treatments. The pH value of LSBM treatments was higher than control treatment (p<0.05). The $NH_3$-N concentration, VFA concentration and rumen microbial synthesis of LSBM treatments were lower than control (p<0.05). The undegradable protein (UDP) showed LSBM Na 2% (45.28%), LSBM Sol 2% (43.52%) and LSBM Heat 2% (43.49%) higher than control (41.55%), respectively (p<0.05). Those experiments were designed to improve by-pass protein of diet and milk protein in the dairy cows. We will conduct those experiments the in vivo test by LSBM treatments in dairy cows diet.

Application of Animal Excreta for Forage Production on Uncultivated Rice Paddy (유휴 논토양에서 가축분뇨를 이용한 조사료의 생산)

  • 이주삼;조익환;안종호;김성규
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.15 no.3
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    • pp.175-185
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    • 1995
  • This experiment was carried out to investigate the optimum rates of animal excreta(cattle slurry-N) for the highest dry matter production and improve the nutritive values of reed canarygrass with different cutting frequency. The results are summarized as follows; The highest relative dry matter yields for annual dry matter yield were 42.2% and 45.2% at 3rd cut in 3 and 4 cuttings, and 34.7% at 4th cut in 5 cuttings, respectively. The annual dry matter yields of non slurry-N application plot showed were from 6.8 tons to 8.0 tons/ha in all cutting frequencies. The highest annual dry matter yield obtained was in 3 cuttings. The annual dry matter yield increased with an increase of applied rates of slurry-N in all cutting frequencies. Annual dry matter yield was produced by 3.3 tons/ha at rates of 90 kg N/ha/cut in 3 cuttings, and more 1.7 tonsha and 2.4 tons/ha at rates of 30 kg N/ha/cut in 4 and 5 cuttings than that of non slurry-N application plots. The contents of crude protein were 12.01% and 15.0% at rates of 90 kg N/ha/cut in 3 and 4 cuttings, and 16.59% at rates of 120 kg N/ha/cut in 5 cuttings, respectively. On the contrary, the content of acid detergent fibre(ADF) showed the lowest values at same rates of slurry-N application in each cutting. J. The average content of crude protein was significantly increased with cutting frequencies, and they were 11.43%, 13.53% and 15.53% in 3, 4 and 5 cuttings, respectively. The average contents of acid detergent fibre(ADF) were 40.27%, 40.53% and 37.06% in 3, 4 and 5 cuttings. The values of 5 cuttings were significantly lower than other cutting frequencies, but the values of acid detergent fibre(ADF) was not significantly different between 3 and 4 cuttings. 6. The efficiency of dry matter production to slurry-N application rates showed the highest values of 18.9 kg and 15.7 kg DM/kg N at rates of 30 kg N/ha/cut in 3 and 5 cuttings, and 16.3 kg DM/kg/ N at rates of 90 kg N/ ha/cut in 4 cuttings. The efficiency of total nitrogen yield to slurry-N application rates were the highest values of 0.51 kg and 0.43 kg W k g N at rates of 30 kg N/ha/cut in 4 and 5 cuttings, and 0.52 kg TN/kg N at rates of 90 kg N/ha/cut in 3 cuttings, respectively. 7. The ranges of economic slurry-N rates were estimated as the 107.2-151.0 kglha, 359.1-375.7 kgha and 160.3-236.9 kg/ha in 3, 4 and 5 cuttings, and marginal dry matter yields were 9.6-10.0 tons/ha, 12.4-12.6 tons/ha and 9.0-9.7 tons/ha in 3, 4 and 5 cuttings, respectively. 8. The limiting sluny-N application rates to maintain the highest dry matter yields were estimated to be 420.0 kg/ ha, 440.6 kg/ha and 666.3 kg/ha in 3, 4 and 5 cuttings.

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Effects of Blended Essential Oil(CRINA®) Supplementation on the Performance, Nutrient Digestibility, Small Intestinal Microflora and Fatty Acid Composition of Meat in Broiler Chickens (사료중 Blended Essential Oil(CRINA®) 첨가가 육계의 생산성과 영양소 이용률, 소장 내 미생물 균총 및 계육내 지방산 조성에 미치는 영향)

  • Suk, J.C.;Lim , H.S.;Paik, I.K.
    • Journal of Animal Science and Technology
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    • v.45 no.5
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    • pp.777-786
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    • 2003
  • An experiment was conducted to investigate the effects of supplementary Blended essential oil(CRINA$^{\circledR}$) on the performance, nutrient availability, fatty acid composition of leg muscle, small intestinal microflora and blood parameters in broiler chickens. One thousand unsexed day-old broiler chickens were assigned to five treatments : control(T1), 5ppm avilamycin(starter diet) & 5ppm flavomycin(grower diet) T2, 5ppm avilamycin(starter diet) & 50ppm CRINA$^{\circledR}$(grower diet) T3, 50ppm CRINA$^{\circledR}$(starter & grower diet) T4, 50ppm CRINA$^{\circledR}$+ 500ppm lactic acid$^{\circledR}$ (starter & grower diet) T5. Each treatment had four replications of 50 birds each. Growth performance was significantly improved by dietary supplements(T2-T5). There were no significant differences among treatment T2, T3, T4 and T5. Feed intake was not significantly different among treatments. Dietary supplementation of CRINA$^{\circledR}$(T3, T4, T5) resulted in significant(p〈0.05) improvement in feed/gain(F/G) during finishing period (4-5weeks). The birds fed CRINA$^{\circledR}$ supplemented diet(T4) showed significantly(p〈0.05) higher availability of crude fat, methionine and methionine + cystine than those fed antibiotics supplemented diet(T2). Mortality was not significantly affected by treatments. The colony forming unit(CFU) of E.coli in small intestinal content was significantly lower in antibiotics & CRINA$^{\circledR}$(T3) compared to CRINA$^{\circledR}$ treatment(T4)(P〈0.05). CFU of Cl. perfringens was low in CRINA$^{\circledR}$(T4) but not different significantly with other treatments. Serum triglyceride level of birds fed CRINA$^{\circledR}$ + lactic acid diet(T5) was significantly lower(p〈0.05) than those fed antibiotics supplemented diet(T2). Cholesterol level of the birds fed antibiotics(T2) or CRINA$^{\circledR}$ + lactic acid supplemented diet(T5) was significantly higher(p〈0.05) than other treatments. HDL level of birds fed control diet was significantly lower(p〈0.05) than that of others. The levels of serum IgG were not significantly different among treatments. Major fatty acids composition of leg muscle fat was significantly influenced by treatments. Control group showed significantly higher palmitic acid(C$_{16:0}$) and steraric acid(C$_{18:0}$) content than other treatments(p〈0.05). Content of oleic acid(C$_{18:1}$), however, was significantly lower in the control than others treatments. Content of linolenic acid(C$_{18:3}$) was significantly higher in CRINA$^{\circledR}$+ lactic acid(T5) than antibiotics & CRINA$^{\circledR}$(T3) treatments. Total saturated fatty acids content was higher and total unsaturated fatty acids were lower in the leg muscle fat of the control than that of other treatments. It is concluded that CRINA$^{\circledR}$ supplementation improved growth rate and F/G ratio in broilers. The combination of CRINA$^{\circledR}$ with either antibiotics or lactic acid did not show any additive or synergistic effects in broiler chickens .

A Study of Guidelines for Genetic Counseling in Preimplantation Genetic Diagnosis (PGD) (착상전 유전진단을 위한 유전상담 현황과 지침개발을 위한 기초 연구)

  • Kim, Min-Jee;Lee, Hyoung-Song;Kang, Inn-Soo;Jeong, Seon-Yong;Kim, Hyon-J.
    • Journal of Genetic Medicine
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    • v.7 no.2
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    • pp.125-132
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    • 2010
  • Purpose: Preimplantation genetic diagnosis (PGD), also known as embryo screening, is a pre-pregnancy technique used to identify genetic defects in embryos created through in vitro fertilization. PGD is considered a means of prenatal diagnosis of genetic abnormalities. PGD is used when one or both genetic parents has a known genetic abnormality; testing is performed on an embryo to determine if it also carries the genetic abnormality. The main advantage of PGD is the avoidance of selective pregnancy termination as it imparts a high likelihood that the baby will be free of the disease under consideration. The application of PGD to genetic practices, reproductive medicine, and genetic counseling is becoming the key component of fertility practice because of the need to develop a custom PGD design for each couple. Materials and Methods: In this study, a survey on the contents of genetic counseling in PGD was carried out via direct contact or e-mail with the patients and specialists who had experienced PGD during the three months from February to April 2010. Results: A total of 91 persons including 60 patients, 49 of whom had a chromosomal disorder and 11 of whom had a single gene disorder, and 31 PGD specialists responded to the survey. Analysis of the survey results revealed that all respondents were well aware of the importance of genetic counseling in all steps of PGD including planning, operation, and follow-up. The patient group responded that the possibility of unexpected results (51.7%), genetic risk assessment and recurrence risk (46.7%), the reproduction options (46.7%), the procedure and limitation of PGD (43.3%) and the information of PGD technology (35.0%) should be included as a genetic counseling information. In detail, 51.7% of patients wanted to be counseled for the possibility of unexpected results and the recurrence risk, while 46.7% wanted to know their reproduction options (46.7%). Approximately 96.7% of specialists replied that a non-M.D. genetic counselor is necessary for effective and systematic genetic counseling in PGD because it is difficult for physicians to offer satisfying information to patients due to lack of counseling time and specific knowledge of the disorders. Conclusions: The information from the survey provides important insight into the overall present situation of genetic counseling for PGD in Korea. The survey results demonstrated that there is a general awareness that genetic counseling is essential for PGD, suggesting that appropriate genetic counseling may play a important role in the success of PGD. The establishment of genetic counseling guidelines for PGD may contribute to better planning and management strategies for PGD.

An Empirical Study on Statistical Optimization Model for the Portfolio Construction of Sponsored Search Advertising(SSA) (키워드검색광고 포트폴리오 구성을 위한 통계적 최적화 모델에 대한 실증분석)

  • Yang, Hognkyu;Hong, Juneseok;Kim, Wooju
    • Journal of Intelligence and Information Systems
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    • v.25 no.2
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    • pp.167-194
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    • 2019
  • This research starts from the four basic concepts of incentive incompatibility, limited information, myopia and decision variable which are confronted when making decisions in keyword bidding. In order to make these concept concrete, four framework approaches are designed as follows; Strategic approach for the incentive incompatibility, Statistical approach for the limited information, Alternative optimization for myopia, and New model approach for decision variable. The purpose of this research is to propose the statistical optimization model in constructing the portfolio of Sponsored Search Advertising (SSA) in the Sponsor's perspective through empirical tests which can be used in portfolio decision making. Previous research up to date formulates the CTR estimation model using CPC, Rank, Impression, CVR, etc., individually or collectively as the independent variables. However, many of the variables are not controllable in keyword bidding. Only CPC and Rank can be used as decision variables in the bidding system. Classical SSA model is designed on the basic assumption that the CPC is the decision variable and CTR is the response variable. However, this classical model has so many huddles in the estimation of CTR. The main problem is the uncertainty between CPC and Rank. In keyword bid, CPC is continuously fluctuating even at the same Rank. This uncertainty usually raises questions about the credibility of CTR, along with the practical management problems. Sponsors make decisions in keyword bids under the limited information, and the strategic portfolio approach based on statistical models is necessary. In order to solve the problem in Classical SSA model, the New SSA model frame is designed on the basic assumption that Rank is the decision variable. Rank is proposed as the best decision variable in predicting the CTR in many papers. Further, most of the search engine platforms provide the options and algorithms to make it possible to bid with Rank. Sponsors can participate in the keyword bidding with Rank. Therefore, this paper tries to test the validity of this new SSA model and the applicability to construct the optimal portfolio in keyword bidding. Research process is as follows; In order to perform the optimization analysis in constructing the keyword portfolio under the New SSA model, this study proposes the criteria for categorizing the keywords, selects the representing keywords for each category, shows the non-linearity relationship, screens the scenarios for CTR and CPC estimation, selects the best fit model through Goodness-of-Fit (GOF) test, formulates the optimization models, confirms the Spillover effects, and suggests the modified optimization model reflecting Spillover and some strategic recommendations. Tests of Optimization models using these CTR/CPC estimation models are empirically performed with the objective functions of (1) maximizing CTR (CTR optimization model) and of (2) maximizing expected profit reflecting CVR (namely, CVR optimization model). Both of the CTR and CVR optimization test result show that the suggested SSA model confirms the significant improvements and this model is valid in constructing the keyword portfolio using the CTR/CPC estimation models suggested in this study. However, one critical problem is found in the CVR optimization model. Important keywords are excluded from the keyword portfolio due to the myopia of the immediate low profit at present. In order to solve this problem, Markov Chain analysis is carried out and the concept of Core Transit Keyword (CTK) and Expected Opportunity Profit (EOP) are introduced. The Revised CVR Optimization model is proposed and is tested and shows validity in constructing the portfolio. Strategic guidelines and insights are as follows; Brand keywords are usually dominant in almost every aspects of CTR, CVR, the expected profit, etc. Now, it is found that the Generic keywords are the CTK and have the spillover potentials which might increase consumers awareness and lead them to Brand keyword. That's why the Generic keyword should be focused in the keyword bidding. The contribution of the thesis is to propose the novel SSA model based on Rank as decision variable, to propose to manage the keyword portfolio by categories according to the characteristics of keywords, to propose the statistical modelling and managing based on the Rank in constructing the keyword portfolio, and to perform empirical tests and propose a new strategic guidelines to focus on the CTK and to propose the modified CVR optimization objective function reflecting the spillover effect in stead of the previous expected profit models.