• Journal of The Korean Association For Science Education
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• v.22 no.4
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• pp.872-881
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• 2002

Student questioning is included in the priority of science literacy, to enable students to solve problems by exploring questions, communicating and constructing knowledge(AAAS, 1989). Also, the essence of student questioning in science lies in its function as a link between thinking and learning. But educators did not pay much attention to students' questioning in Korea. The purpose of this study was to investigate the effects of science question enhancement instruction on students' science questioning level and achievement. Also, this study showed the effects of other variables(logical thinking, science achievement, interest, and gender) on students' science questioning level. The pretest-posttest control group design group design was used. The sample was consisted of 80 second grade middle school students in experimental group(Science question enhancement instruction) and 74 students in control group(Traditional learning). Students in both groups were received identical content instruction on the unit 'Structures and functions of plant'. These groups were treated for 15 hours during 6 weeks. Students' questions were rated using the four levels described by the Middle School Students' Science Question Rating Scale(r= .96,)(Cuccio-Schirripa & Steinner, 2000). Science achievement data were collected using a 17 item multiple choice test(Cronbach ${\alpha}$= .84). To investigate students' logical thinking ability, a abridged GALT(Cronbach ${\alpha}$= .69) was used. Five-way ANOVA, ANCOVA, and multiple regression analysis were used to analyze the results. The results indicated that students who received instruction on researchable questioning outperformed those students who were not instructed on high-order questioning(p< .01). Results of correlations indicated that instruction(r= .640), science achievement(r= .311) and logical thinking ability(r= .212) was significantly and positively related with students' questioning level. But, interest and gender did not show any significant correlation with students' questioning level. Science question enhancement instruction was more effective on science achievement than the traditional instruction(p< .01).

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.46-52
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• 2009

Statement of problem: Recently, titanium has become popular as superstructure material in implant dentistry because titanium superstructure can be easily milled by means of computer-aided design and manufacture (CAD/CAM) technique. But retention form such as nail head or bead cannot be cut as a result of technical limitation of CAD/CAM milling and bond strength between titanium and porcelain is not as strong as that of conventional gold or metal alloy. Purpose: The objective of this study was to evaluate the shear bond strength of three different materials: heat curing resin, composite resin, porcelain which were bonded to grade II commercially pure Titanium (CP-Ti). Material and methods: Thirty seven CP-Ti discs with 9 mm diameter, 10 mm height were divided into three groups and were bonded with heat curing resin (Lucitone 199), indirect composite resin (Sinfony), and porcelain (Triceram) which were mounted in a former with 7 mm diameter and 1 mm height. Samples were thermocycled for 1000 cycles at between $5-55^{\circ}C$. Shear bond strength (MPa) was measured with Instron Universal Testing Machine with cross head speed of 1 mm/min. The failure pattern was observed at the fractured surface and divided into adhesive, cohesive, and combination failure. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (${\alpha}=0.05$). Results: Lucitone 199 ($17.82{\pm}5.13\;MPa$) showed the highest shear bond strength, followed by Triceram ($12.97{\pm}2.11\;MPa$), and Sinfony ($6.00{\pm}1.31\;MPa$). Most of the failure patterns in Lucitone 199 and Sinfony group were adhesive failure, whereas those in Triceram group were combination failure. Conclusion: Heat curing resin formed the strongest bond to titanium which is used as a CAD/CAM milling block. But the bond strength is still low compared with the bond utilizing mechanical interlocking and there are many adhesive failures which suggest that more studies to enhance bond strength are needed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.8-18
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• 2005

We studied seasonal distribution of the microphytobenthos and their primary production with $C^{14}$ method and carried out pigment analysis with HPLC in an estuarine mudflat of the Ganghwa Island, Korea from May 2002 to April 2004. The abundances of microphytobenthos were higher at the middle than upper part and lower part of intertidal flat. Abundances of microphytobenthos ranged from $2.3{\times}10^5\;cells\;cm^{-2}$ to $140.9{\times}10^5\;cells cm^{-2}$. The bloom of microphytobenthos was observed in the early spring and then it decreased from spring to summer and autumn. The pennate diatom was a predominated group among the microphytobenthos in this area. The dominant species were Paralia sulcata, Cylindrotheca closterium and Nitzschia sp.. Nitzschia sp. and Cylindrotheca closterium were predominant in February. The results of pigment analysis suggest the presence of diatoms, euglenophytes, chlorophytes, cyanobacteria, cryptophytes, chrysophytes, prymnesiophytes, dinoflagellates and prasinophytes. The biomass of microphytobenthos ranged from 1.18 to 34.25 mg chl-a $m^{-2}$, with a mean of 7.60 mg chl-a $m^{-2}$. The mean ratio of Fuco/Chl a was 0.7 which indicates that most of biomasses of microphytobenthos were due to diatoms. The ratios of Chl b/Chl a ranged from 0 to 0.82(with a mean of 0.17), implying that euglenophytes and chlorophytes lived together in special period seasonally. Temporal variation of primary production ranged from 4.2 to 113.0 $mgC{\cdot}m^{-2}{\cdot}hr^{-1}$(mean value was 33.9 $mgC{\cdot}m^{-2}{\cdot}hr^{-1}$ and initial slope$({\alpha})$ was measured from 0.002-0.005$(mgC\;mgchl-a^{-1}\;hr^{-1}){\cdot}({\mu}E\;m^{-2}\;s^{-1})^{-1}$. Assimilation number$(P_m)$ was in the range of 0.50-1.32 $mgC{\cdot}mgChl-a{\cdot}hr^{-1}$ and daily primary production ranged from 20.9 to 678.1 $mgC{\cdot}m^{-2}{\cdot}d^{-1}$(mean value was 206.72 $mgC{\cdot}m^{-2}{\cdot}^{-1}$).

• Journal of Embryo Transfer
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• v.22 no.1
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• pp.9-13
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• 2007

The objective of this study was to investigate the relationship between various estrous behavior and ovulation time, and to determine which estrous behavior could predict ovulation time more accurately. In total, 37 ovulations and 28 estrous detection were observed in 51 Holstein-Friesian dairy cows. Various estrous behavior were observed during 72 h from two days after $PGF_2{\alpha}$ injection and their relation with the time of ovulation (ultrasound examinations at 4-h intervals) was investigated. In estrous periods, the rate of sniffing, chin resting, mounting, standing heat was 81%, 78%, 78% and 56%, respectively. Ovulation occurred $25.6{\pm}7.9h$ after onset of estrus (ranging between 7 and 37h) and $13.4{\pm}7.1h$ after end of estrus (ranging between 1 and 28h). Interval between onset of estrus and ovulation time was significantly (p<0.05) shorter for standing heat $(17.33{\pm}5.83h)$ than for mounting, sniffing and chin resting $(23.58{\pm}5.12h,\;24.25{\pm}6.09h,\;23.42{\pm}6.04h)$. In 88% of the animals that displayed mounting, ovulation occurred between $16{\sim}28h$ after onset of mounting. Onset of standing heat, sniffing and chin resting occurred between $10{\sim}22(81%)h,\;16{\sim}28(79%)h\;and\; 19{\sim}31(79%)h$ before ovulation respectively. Sniffing and chin resting were displayed during the non-estrous period and are therefore, not useful predictors of ovulation time. The standing heat and mounting can be a good predictor for time of ovulation but the disadvantage of using standing heat is that only a limited number of cows display standing heat. Thus, it is concluded that mounting behavior could be the best predictor for time of ovulation.

• Journal of Aquaculture
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• v.20 no.4
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• pp.219-225
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• 2007

This study investigated the correlationship between artificial maturation season and reproduction coefficient of cultured eel Anguilla japonica from May (spring) to next January (winter). The brood stock, female eels ($400{\sim}600\;g$) were artificially matured by weekly intramuscular injections of salmon pituitary extracts (SPE, 20 mg/fish) to induce a completion of vitellogenesis. After completion of vitellogenesis, final oocyte maturation and ovulation was induced by injection of $17{\alpha}$, $20{\beta}-dihydroxyprogesterone$ (DHP) at about $2\;{\mu}g/g$ body weight. Most fish ovulated $15{\sim}18\;h$ following the DHP injection. The ovulated fish were induced to natural spawning or artificial fertilization by the dry method. Males ($200{\sim}350\;g$) were received weekly intramuscular injections of human chorionic gonadotropin (HCG) at a dosage of 1 IU/g body weight to induce testicular maturation and spermiation. Seasonal reproduction coefficient which includes the rate of ovulation, buoyancy, fertilization and hatching of eggs in the artificially matured eel during spring to summer ($May{\sim}July$) were significantly higher than the other season, while there were no significant difference among spring and summer (P<0.05). Furthermore, the number of eggs spawned and larvae hatched in the artificially maturated eel during spring to summer ($May{\sim}July$) were significantly higher than the other season, while there were no significant difference in spring and summer (P<0.05). These results indicate that artificial maturation by hormone treatment of A. japonica was successful only during spring to summer, which is the maturation period in the wild stock in nature. Consequently, it is possible to determine the period of artificially induced sexual maturity by the reproduction coefficient which includes the rate of ovulation, buoyancy, fertilization and hatching of eggs in the cultured eel A. japonica.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.174-187
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• 2008

In an effort to identify structure and function of microbial loop in Paldang reservoir, we monitored environmental and biological factors at Kyungan stream (station K), Paldang dam (station P) and the confluence of North and South Han River (station M) from March to December, 2005. DOC concentration was higher in March to May and November than the others. Nutrient concentration in station K detected relatively higher than that of two stations. Both of phosphate and silicate gradually increased at all stations until September, after then decreased. The highest Chl-$\alpha$ concentration was observed at all stations in April, and November. The carbon biomass of bacteria and HNF were relatively higher in March, May and August than the others, whereas that of the ciliate showed no significant difference in monthly fluctuation. Nevertheless, the significant relationships revealed between ciliate (P<0.001) and HNF (P<0.05) and bacterial density. Tintinnopsis cratera, Didinium sp., Vorticella sp., Paramecium sp. and Strombidium sp. were dominant species in ciliate community. The dominant species of phytoplankton were Stephanodiscus hantzschii and Cyclotella meneghiniana at almost stations in Spring, Summer and Autumn. However, Aulacoseira granulata accounted for >95% of phytoplankton biomass at station P and M in Autumn. The carbon biomass of zooplankton was highest at station P and M in June, and relatively higher biomass observed at all stations in August, October and November. Diaphanosoma brachyurum and Bosmina longirostris were dominant in stations P and M of June and in all stations of October and November, respectively. The maximum growth (A. granulata: $0.17\;d^{-1}$, S. hantzschii: $0.14\;d^{-1}$) and grazing rate (A. granulata: 1.93 preys $d^{-1}$, S. hantzschii: 1.63 preys $d^{-1}$) of Bosmina longirostris revealed in algal preys as Aulacoseira granulata and Stephanodiscus hantzschii. In conclusion, these results suggest that bacteria and phytoplankton can play the most crucial source as prey within microbial food chain in Spring and Summer and grazing food chain in Autumn, respectively.

• Tuberculosis and Respiratory Diseases
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• v.50 no.2
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• pp.158-170
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• 2001

Background : Although an oxidants and antioxidants imbalance has been considered in the pathogenesis of chronic obstructive pulmonary disease (COPD), there is a paucity of reports focussing on the smoking-induced changes of oxidants and antioxidants in COPD. Method : The concentration of antioxidants (ascorbic acid, uric acid, retinol, and $\alpha$- & $\gamma$-tocopherol) was measured in the serum and induced sputum of 30 healthy controls and 34 stable COPD patients using high performance liquid chromatography (HPLC). The inhibition of lipid peroxidation as an index of antioxidant capacity was measured in the serum by a TBA assay. Results : The serum concentration of ascorbic acid, $\alpha$-tocopherol, and retinol were significantly lower in the patients with COPD than in healthy controls ($484.8{\pm}473.3$ vs $1497.8{\pm}819.2\;pmol/L$, $48.38{\pm}17.34$ vs $73.96{\pm}26.29\;pmol/L$, p<0.001, and $9.51{\pm}8.33$ vs $15.01{\pm}5.88\;pmol/L$, p<0.05, respectively, mean$\pm$SD). However, there were little differences in the ascorbic acid and uric acid concentrations in the induced sputum between the COPD patients and the controls. The induced sputum to serum ratio of ascorbic acid was significantly higher in COPD patients compared with healthy control (0.375 vs 0.085, p<0.05). In the normal controls, the serum ascorbic acid concentration was lower in smokers than in nonsmokers ($1073{\pm}536$ vs $1757{\pm}845\;pmol/L$, p<0.05), but the level was still higher than that of the COPD patients (p<0.05). The serum retinol levels were correlated with $FEV_1$ in COPD patients (r=0.58, p<0.05). The products of lipid peroxidation were increased in normal smokers and COPD compared with norma1 nonsmokers ($115.56{\pm}19.93$ vs $120.02{\pm}24.56$ vs $91.87{\pm}20.71\;{\mu}mol/{\mu}mol$ Pi of liposome, p<0.05). Conclusion : Cigarette smoking may induce the dep1etion of serum antioxidants and this depletion of antioxidants is suggested to play a role in the pathogenesis of COPD.

• Korean Journal of Psychosomatic Medicine
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• v.8 no.1
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• pp.72-87
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• 2000

Objectives : This study was to provide normative data of Korean version of DSI(K-DSI), a sensitive measure of relatively minor stressors that could be administered daily. Methods : K-DSI was administered in 524 adults, age of 19 or over, daily for 1 week. On the seventh day, Becks Depression Inventory(BDI), State-Trait Anxiety Inventory(STAI), and Social Readjustment Rating Scale(SRRS) were also given to test the convergent validity. Analyses(ANOVA or t-test) were conducted to examine the potential effects of demographic variables on K-DSI score. Internal consistency for reliability and Pearson's corelation coefficient with BDI, STAI, SRRS for convergent validity were computed. Percentile scores were calculated for daily and weekly K-DSI Event, Impact and I/E Ratio scores. Results : K-DSI scores in women were higher than those in men. According to age and educational level, the younger and the higher educational level the normative groups were, the higher were K-DSI scores. Among the 5 categories of the inventory, the category of cognitive stressors was highest. Internal consistency of K-DSI(Cronbach's $\alpha$) was .99. Daily and Weekly events and impacts scores were significantly correlated with the scores of State-Trait Anxiety Inventory, Social Readjustment Rating Scale, and Beck Depression Inventory. 75 percentile scores of the daily/weekly Events, Impacts, and I/E ratio were 17/118 - 124, 57/368 - 389 and 3.48 - 3.49/3.47 - 3.48 respectively. And 95 percentile scores of daily/weekly Events, Impacts, and I/E ratio were 57/151- 161, 405/1038 - 1122, and 4.72 - 4.86/4.46 - 4.56 respectively. Conclusion : Reliability and validity of K-DSI were tested satisfactorily. Authors presented the normative data of K-DSI for Koreans. K-DSI could be a useful measure in clinical settings or researches to assess the minor stressors frequently experienced in everyday life.

• Food Science and Preservation
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• v.22 no.3
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• pp.335-344
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• 2015

The objective of this study was to determine the rheological characteristics and sensory evaluation of yanggaeng by using the functional properties of Momordica charantia. Dried Momordica charantia was roasted at $180^{\circ}C$ to remove its bitter taste. The results of the study were as follows : The phenolic compound of Momordica charantia was $6.30{\pm}0.17mg/g$ in water extracts, which was the highest extractive rate. The anti-oxidant activity of non-roasted and roasted samples was determined in various phenolic concentrations at $50{\sim}200{\mu}g/mL$. The DPPH activities of non-roasted and roasted Momordica charantia water and ethanol extracts were 74.06~92.71% and 86.06~94.07%, respectively. The ABTS were 36.26~98.03% and 67.02~99.60% in water and ethanol extracts, respectively. The anti-oxidant protection factor of water and ethanol extracts were 2.19~2.25 PF and 2.20~2.36 PF respectively, and TBARS were 13.81~40.97% and 23.32~82.47%, respectively. The anti-oxidant activity of ethanol extracts was higher than that of water extracts at low phenolics concentration of $50{\mu}g/mL$, while the roasted sample was higher than the sample that was not roasted. The ${\alpha}$-glucosidase inhibition activity of non-roasted Momordica charantia ethanol extracts was higher than that of water extracts, showing that there were increasing pattern depending on the increases in the phenolics concentration of Momordica charantia. The texture, such as hardness, springiness, cohesiveness, chewiness and color changed in proportion to the concentration of Momordica charantia powder. Moreover sensory characteristics, such as color, flavor, taste, texture and overall acceptability of the non-roasted sample changed in proportion to the concentration of Momordica charantia powder. However, in the roasted sample, the sensory characteristics was improved at a lower concentration (below 1%). Thus, when the yanggang was prepared by Momordica charantia powder as a minor ingredient, it would be desirable to add it after roasting, in consideration of its functional and sensory properties, and at appropriate concentration on below 1%.

• Food Science and Preservation
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• v.23 no.6
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• pp.778-787
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• 2016

Fermented vinegars using pear was compared according to the appled side materials. Quality characteristics of three kinds of the fermented vinegars (pear vinegar, PV; pear black rice vinegar, PBV; pear mint vinegar, PMV) were investigated, which includes pH, total acidity, colors, the contents of sugar, amino acids, total polyphenol, and total flavonoid, ${\alpha}^{\prime}{\alpha}-diphenyl-{\beta}-pycrylhydrazyl$ (DPPH) radical scavenging ability, and sensory evaluation. Brown rice vinegar (BRV) was used as a control. The pH and total acidity of the fermented pear vinegars were significantly different showing the range of 3.17~3.43 and 4.01~5.05%, respectively (p<0.05). The sugar contents of PV and PMV were significantly higher than other vinegars (p<0.05). L, a, and b values were the highest in PV, PBV, and PMV, respectively. Among the four vinegars, the essential amino acids were the highest in PV with the order of lysine, isoleucine, valine, and threonine. Besides, the fermented pear vinegars have many non-essential amino acids such as glutamic acid and aspartic acid. The aspartic acid content was the highest in PV while glutamic acid content was the highest in BRV. The total polyphenol content was the highest in PV while total flavonoid content was the highest in PBV. The DPPH radical scavenging ability (%) was the highest in PV. In sensory evaluation, PBV showed the highest color, taste and overall preference scores. These results show that pear would be desirable to prepare high-quality vinegars and functional foods.