• 한국지역사회생활과학회지
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• 제23권4호
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• pp.447-455
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• 2012

The purpose of this study was to investigate children's conception of liquid conservation according to their ages and tasks in the boiling phenomenon The subjects were thirty 4-year-olds, thirty 6-year-olds, and thirty 8-year-olds recruited from two day-care center, one kindergarten, and one elementary school, in Seoul. Statistical methods used for data analysis were frequencies, percentiles, means, standard deviations and repeated measures ANOVA. As the result, there was a significant difference in children's conception of liquid conservation in the boiling of water according to their ages. 8-year-old children showed higher levels of cognition than 4 and 6-year-olds. There was no difference in children's conception of liquid conservation in the boiling of water according to tasks.

• 한국생활과학회지
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• 제22권1호
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• pp.17-27
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• 2013

The purpose of this study is to investigate children's liquid conservation concept according to their ages and task-situations in the water evaporation phenomenon. Thirty from each 4-, 6- and 8-year-old age groups (total of 90 subjects) were selected for this study. The subjects were recruited from two day-care centers, a kindergarten, and an elementary school, in Seoul. Statistical methods used for data analysis were frequencies, percentiles, means, standard deviations and repeated measures ANOVA. As a result, there was a significant difference in children's liquid conservation concept in the evaporation of water according to their ages and task-situations. 8-year-old children showed levels of cognition than 4- and 6-year-olds. Children showed higher levels of cognition in the task of drying than in the task of water level changes.

• 보존과학회지
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• 제17권
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• pp.95-101
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• 2005

• 아동학회지
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• 제2권
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• pp.41-53
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• 1981

The purpose of this study was to find out conservation concept acquisition in children of pre-operational and concrete periods. The data in this study were obtained through experimental methods with 62 children(28 males and 34 females) of 3-11 ages in Korean rural areas. The Piagetian instruments devised by Gelman were used for the study ; length, liquid, quantity, mass, and volume conservation tasks. Percentile and $x^2$-test were applied for the statistical analysis of data: and the results of the experiment are as follows: 1) Most children aged 3-9 years did not appear to understand that the length of sticks stayed the same regardless of position. 2) In liquid quantity conservation, children centered their attentions on one aspect ; juice level or number of container. Their conservation concept was developed correlating with ages. 3) In the experiment of mass conservation by using play dough, only 7.1% of children of pre-operational period and 47.1% of concrete period affirmed that the amounts of play dough were same after changed shape. 4) In volume task, 29.4% children aged 7 to 11 years admitted to conservation. 5) It is found that girls acquired length conservation earlier than boys, while there was no significant difference between boys and girls in other conservation tasks.

• 아동학회지
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• 제25권1호
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• pp.1-12
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• 2004

This study investigated the relations of children's age, intelligence, and the concept of conservation to their learning of English. Ten 4-year-old children from 1 child-care center and 13 7-year-old children from 1 elementary school were tested after completion of 8 sessions of experimental English classes. Children's intelligence was measured by K-WPPSI for 4-year olds and K-WISC for 7-year-olds. Children were tested for number and liquid conservations. A Korean teacher with 11 years of experience of teaching children at American elementary schools taught the 2 groups with the same subjects and methods. Data were analysed by independent samples t-test, Mann-Whitney U test, and Pearson's r. The results showed that children's age and the concept of conservation were related to English learning. No statistically significant relationship with IQ was found.

• 보존과학회지
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• 제37권6호
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• pp.801-806
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• 2021

전통 접착 소재인 아교의 사용성과 해초 추출물 카라기난의 겔화 현상을 개선하기 위해 두 재료를 혼합하여 목재 보존용 액상형 접착제를 제조하였으며, 9종의 천연 및 합성 접착제와의 물성 비교를 통해 적용 가능성을 확인하였다. 제조한 목재 접착제는 15 wt% 아교 수용액과 λ-carrageenan, 항균제, 소포제 등을 혼합하였으며, 1.80 Mpa의 최대 접착 강도를 확인하였다. 비교 결과 5종의 전통 천연 접착 성분(수용액)과 Polyvinyl acetate 기반 접착제 1종보다 우수한 접착 강도가 나타났으며, 총호기성생성균수와 유해성(TVOC, HCHO, 중금속) 시험 결과 불검출로 항균성과 안정성을 확인하였다.

• 한국분무공학회지
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• 제12권2호
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• pp.79-85
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• 2007

In this study, the effect of jet velocity profile on the thickness and velocity of the liquid sheet formed by two impinging low speed jets was investigated. To predict the distribution of thickness and velocity of liquid sheet theoretically, the jet velocity profile which was measured experimentally was adopted in addition to the constant jet velocity as well as Poiseuille's parabolic profile. For three cases, the distribution of thickness and velocity of liquid sheet was analytically predicted by solving conservation equations including stagnation point. The predicted results were compared with previous experimental results. The jet velocity profile definitely affected the resulting characteristics of liquid sheet. The distribution of thickness and velocity of liquid sheet was more close to the measured results compared with that which was predicted by the assumption of constant jet velocity.

• Journal of the Korean Wood Science and Technology
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• 제51권2호
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• pp.69-80
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• 2023

This study conducted scientific analyses on eight objects of wooden lacquerware to understand the manufacturing techniques of wooden lacquerware in the late Joseon Dynasty. The results of lacquer layer analysis with a microscope and scanning electron microscopy-energy dispersive X-ray spectrometry revealed that most samples were composed of 1-3 lacquer layers. Moreover, a red-colored layer was found to be red ocher and cinnabar, and Fourier-transform infrared spectroscopy analysis was carried out to determine the components of the lacquer layer. The detected components were mostly lacquer and partially cashew shell nut liquid.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권3호
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• pp.119-127
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• 2005

Liquid pressure amplifiers have been proposed as an energy saving technology for vapor compression refrigeration systems configured with direct-expansion evaporators. The technology utilizes a refrigerant pump in the high pressure liquid line as a means of maintaining a suitable pressure differential across the expansion valve while lowering condensing pressure to achieve the reduction of compressor energy consumption. Applications have been proposed on systems ranging from small unitary air-conditioning to large supermarket and commercial refrigeration systems. This paper clarifies the role of such a device in a vapor compression refrigeration system. Limitations are presented and discussed. Finally, results of detailed analyses are presented to quantify the energy consumption both with and without a liquid pressure amplifier in a unitary air conditioning system. The estimated energy savings associated with the installation of a liquid pressure amplifier are minimal.

• 보존과학연구
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• 통권15호
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• pp.21-32
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• 1994

Optimum conditions for benzene synthesis and liquid scintillation counting have been studied for the determination of radiocarbon age. In benzene synthesis the carbon dioxide converted to benzene with high efficiency of 91%. Yields of each step with 10L of carbon dioxide were $CO_2$ $\rightarrow$$C_2H_2$(94%), $C_2H_2$$\rightarrow$$C_6H_6$(96%) and$CO_2$$\rightarrow$$C_6H_6$(91%), respectively. Benzene synthesized from oxalate was measured with purity of 95% by GC /MS. $\delta^13$(C$^13$C/$^12$C) of oxalate was measured to $-24.7\{textperthousand}$ by massspectrometer. For liquid scintillation counting of benzene sample low background and highest FOM were measured in 0.5 ml cocktail and 3 ml standard solution with the range of 15.4∼74.9 KeV window setting. Oxalate and background samples weremeasured to $28.7\pm0.12$cpm and $3.92\pm0.04$ cpm in 15.4∼74.9 KeV