• Korea journal of population studies
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• v.30 no.3
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• pp.137-156
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• 2007

Total fertility rate (TFR) increased from the lowest 1.08 in 2005 to 1.13 in 2006, and a debate is made whether the increase is temporary or continuous as a result of various pro-natal policies. This study intends to explore policy implications revealed in recent fertility change using vital statistics. For this purpose, tempo-adjusted fertility rate by birth order, fertility rate by age of mother and birth order, age-specific fertility for married, and age-specific divorce rate for married are analyzed. The increase of TFR and births for 2006 is largely due to increase of first births at early thirties with slowdown of delayed first marriage and first child birth. The increase of female population (the third wave effect of baby boom) and first marriages of late twenties in 2006 and 2007 would lead to increase of fertility during 2007-2008. But further increase is uncertain because of the decrease trend of marital fertility and increase trend of never-married for twenties. TFRs for first and second births reduced rapidly, while TFRs for third and above births showed no changes, and second births were largely affected by tempo adjustment of fertility. Thus, constructing social environment for first and second births is more effective and necessary than encouraging third births. In addition, social responsibility of child care, child-women health issues due to delayed births, and the need for multi-cultural family support system are discussed.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.32-37
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• 2007

The study was carried out to establish buffer zone for the protection of the non-target organisms by aerial pesticide application. The two pesticide combination of 3-way tank-mixing of three pesticides for aerial application, ferimzone tricyclazole SC + BPMC EC + validamycin-A SL and hexaconzole EC + isoprothiolane EC+phenthoate EC were selected for the simultaneous control of key pests on paddy rice as blast, sheath blight, brown planthopper and moth. Aquatic organisms including killifish and loach in the paddy field and nearby water reservoirs were not affected by aerial application of the pesticides. However, all the water flea were killed, when they were exposed 10 m from the aerially sprayed site, while the water flea exposed in 30 m away from the site were not affected. Honeybees within 50 m in the wind direction and 20 m in the opposite wind direction showed a mortality of $7{\sim}100%$. Residues concentration of the pesticides in paddy water were not detectable level after six days from aerial application. Drifting distance of aerially sprayed droplet from the target area was within 30 m in the wind direction and 20 m in the opposite direction. Consequently, it was the buffer zones in the aerial pesticides application for the protection of the non-target organisms should be at least 50 m for aquatic organisms and 100 m for honeybees.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.187-193
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• 2012

Acute toxicity, water resolvability and short term reproduction test on Japanese medaka (Oriyzias latipes) for evaluating alachlor susceptibility to endocrine system were studied. Alachlor is known for suspected endocrine distruptors. As the results of tests, $LC_{50}$ (Median lethal concentration) was determined as 2.36 (1.994~2.805) mg/L, and test water replaced at 7 day intervals as its water resolvability was less than 20% in 7 days. The short term reproduction tests on Japanese medaka (Oriyzias latipes) were performed with a solvent control group, a treated group (alachlor concentrations of 0.02, 0.04, 0.11, 0.27, 0.68 ppm) and a positive control group (17 ${\beta}$ estradiol, 0.01, 0.1, 0.5 ppb). The number of spawning and embryo rates were declined in a alachlor-dose dependent manner, and the number of unfertilized eggs rates were in contrast increased depending on the concentrations. Further study should be needed to confirm whether the adverse effects may be effected by the concentrations. Additionally, alachlor was evaluated as a non-vitellogenin by the result of a test of significance of the vitellogenin content test for determination of the effect of estrogen among the endocrine disruptors.

• Fire Science and Engineering
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• v.23 no.1
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• pp.63-69
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• 2009

Article 36 of the Building Code Enforcement Ordinance requires that an exterior evacuation stairs be installed for the buildings of three stories and over with cultural facilities or gathering places which have over $1,000\;m^2$ floor area of public performance halls or recreational facilities. The concentration of population together with the increase of high-rise buildings in cities call for various precautionary measures to be taken against human disasters. For the past ten years high-rise buildings showed 85% of increase, marking a steep rise. This increase of high-rise buildings may lead to human disasters in urban areas and, in case of fire breakout, may cause great loss of human lives and property damages. The most difficult fire-fighting activities in high-rise building fires are those of evacuation. Because smoke spreads through the upper floors, the securement of evacuation route in high-rise buildings may be the only way to minimize loss of lives. In high-rise buildings exterior escape stairs are necessary because it is difficult to secure evacuation route with only direct stairs or interior stairs. The Building Code now in force provides insignificant coverage on the exterior evacuation route installment and therefore becomes an inadequate means for evacuation route securement in high-rise building fires. To compensate for this inadequacy the Building Code should be revised to include a mandatory clause that an exterior evacuation stairs be established for the buildings of ten stories and over which can be categorized into high-rise building group.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.117-122
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• 1977

Development of new burning additives against nitrate salts used in past tobacco industry examined to reduce harmful nitrogenous compounds in smoke. Among several additives treated, the best effect by means of elevation of combustibility and reduction of tar and nicotin contents in smoke was observed by adding sodium citrate from 0.6 to 1% in tabacco. The following results were obtained through investigating combustibility, chemical composition, and differential thermal analysis of the tabacco treated with the buring additives. 1) The close relation was observed between the levels of the smoke components and combustibility of the treated tabacco. 2) Differential thermal analysis (D.T.A.) of citrate-treated tobacco shows an increase in H. Value and a decrease in L. Value as compared with other tobacco sample. 3) The D.T.A. of sodium-nitrate and sodium-citrate shows that sodium-nitrate gives endothermal reaction at $270^{\circ}$ and $310^{\circ}$ and sodium citrate gives exothermal reaction at $290^{\circ}$ with endothermal reaction at $170^{\circ}\;and\;310^{\circ}$. 4) $Na_3-citrate-treated$ tobacco shows an increase in smoke generation between room temperature and $350^{\circ}$ (Zone A) and a decrease in smoke generation between $350^{\circ}$ and $900^{\circ}$ (Zone B) compared with untreated tobacco. The smoke from these tobacco also contains lower levels of Tar, Nicotine, Phenols, Nitrogen oxides and Benzpyrene, and elevation of static Burning rate.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1232-1240
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• 1996

From January 1990 through June 1995, we operated on 121 patients who were suspected for pulmonary tuberculosis without definite final diagnosis. After operation the final pathologic diagnoses were as follows: 68 pulmonary tuberculosis in which 29 were tuberculoma, 23 lung cancer, 16 bronchiectasis, 6 aspergilloma, 2 lung abscess, 2 benign cyst and 4 others. In 121 cases, 81 were male and 40 were female and the peak age incidence was 4th decade in tuberculosis (39.7%) and 6th and 7th decade in lung cancer (69.6%). The diagnoses in 44 cases presented roentgenographically as pulmonary nodules were pulmonary tuberculosis(29 cases) and lung cancer(15 cases). Tuberculous nodules tended to be smaller in size with calcification and satellite lesions compared to carcinomas. Indications for operation were solitary nodules 44 cases (36.4%); destroyed lobe 31(25.6%); hemoptysis 25 (20.7%); cavitary lesion 11(9.1 %); bronchostenosis 3 (2.5%); destroyed lung 5(4.1 %) and destroyed lung with empyema 2(1.7%). We conclude that preoperatively suspected pulmonary tuberculosis should be distinguished from various pulmonary lesions such as carcinoma, bronchiectasis, aspergilloma, lung abscess and benign cyst. For the possibility of carcinoma, pulmonary nodules of size greater than 3cm, non-calcified, non satellite lesion, newly developed nodule even under the anti-tuberculous medication, negative PPD skin test with elevated CEA level are recommended for an early resectional surgery and follow-up and delayed surgery is recommended in cases such as pulmonary nodules less than 3 cm in size with calcification, satellite lesion, positive PPD skin reaction and elevated ESR, CRP, ALP levels.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.95-108
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• 2022

The increase in the use time of tunnel users due to the lengthening of the road tunnel may increase the evacuation time in case of fire, resulting in a large number of casualties. In order to reduce the casualties caused by fire, the "Road Tunnel Design Manual, Part 6 Tunnel" and "Road Tunnel Disaster Prevention Facility Installation and Management Guidelines" stipulate that ventilation facilities should be installed along with the extension of the tunnel. The ventilation system design factor considers the wind speed of the external natural wind to be at least 2.5 m/s, and it is applied upward according to the characteristics of the tunnel. As a result of analyzing the five-minute average wind speed data in the Daegwallyeong region for the past 6 years, it was analyzed that 15.8% of the windy days were winds of 10 m/s or more, and the maximum was 20 m/s. Therefore, in this study, when a fire occurs in a tunnel, the pattern of natural wind flowing into the tunnel and the backlayering distance of the tunnel fire smoke according to the maximum wind speed were analyzed. As a result, it was analyzed that a backflow of up to 490 m occurs when a gust of 20 m/s blows.

• Journal of Industrial Convergence
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• v.20 no.3
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• pp.11-21
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• 2022

The purpose of this study is to provide fundamental background to improve the quality of teaching and learning performance in online classes by analyzing the students' learning experience aspects on online environment. This study explores the relationship between learning experience and teaching and learning performance according to the online classes types(synchronous/asynchronous class), and identifies the mediation effect of students' perception and attitude toward online classes using Structural Equations Model(SEM). The findings are shown as follows: First, learning experience has positive effect on teaching and learning performance statistically. Second, learning experience has different effect on teaching and learning performance depending on the type of online classes. Specifically, learning experience in synchronous environment has higher influence on teaching and learning performance than in asynchronous environment. On the other hand, perception and attitude toward online classes have greater influence on teaching and learning performance in asynchronous class than in synchronous class. Lastly, the students' perception and attitude toward online classes do not have mediation effects significantly in the relationship between learning experience and teaching and learning performance. The result of this study can be a guide for researcher to approach to teaching and learning performance in online environment of university.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.702-707
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• 2012

During the last few decades, toxic chemicals used in various industries have caused global pollution and the side products such as carbon dioxide and methane gas have contributed to global warming. Thus, it is desirable to develop new alternative solvents. It is well known that ionic liquids display a variety of environmentally friendly physical properties: nonvolatile, nonflammable, wide electrochemical windows, high inherent conductivities, wide thermal operating ranges, chemically inert, and limited miscibilities with organic solvents. Because of these characteristics, ionic liquids are promising candidates as solvents for synthetic chemistries, catalysis, and gas separations. In this study, we synthesized morpholiunium salts as N-ethyl-N-methylmorpholine Bromide, N-butyl-N-methylmorpholine Bromide, N-octyl-N-methylmorpholine Bromide, N-ethyl-N-methylmorpholine Tetrafluoroborate, N-butyl-N-methylmorpholine Tetrafluoroborate, N-octyl-N-methylmorpholine Tetrafluoroborate, N-ethyl-N-methylmorpholine Hexafluorophosphate, N-butyl-N-methylmorpholine Hexafluorophosphate, and N-octyl-N-methylmorpholine Hexafluorophosphate. The melting points, decomposition temperatures and electrochemical stabilities of the salts were measured by DSC, TGA, and CV, respectively. The salts with halide anion showed high melting points ($150{\sim}200^{\circ}C$), low decomposition temperatures ($200{\sim}230^{\circ}C$), narrow electrochemical stabilities (3.4~3.6 V). The synthesized salts with inorganic anions, on the other hand, presented low melting point ($50{\sim}110^{\circ}C$), high decomposition temperatures ($250{\sim}380^{\circ}C$), wide electrochemical stabilities (6.1~6.3 V). We also found that the properties depend on the length of the carbon chain.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.204-221
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• 2020

East Asian countries share a culture of perfuming clothes. The prosperity of the Maritime Silk Road and the incense trade are direct factors that have led to the development of incense culture. Perfuming clothes is a method of applying fragrance by burning incense. The Chinese could make an incense mixture with various types of incense, and records demonstrating use of perfuming clothes tools (熏籠) show that they might have perfumed clothes with incense mixtures. During the Tang dynasty, the incense trade thrived. Examples of ancient literature such as 『千金要方』, 『香譜』, 『香乘』 describe how to make incense for perfuming clothes and how to perfume clothes. 『桂海虞衡志』 and 『諸蕃志』 shows trade partners and goods. Incense was introduced to Korea alongside Buddhist culture. 『買新羅物解』 shows Silla traded incense with Japan. One of the trade goods recorded in 『買新羅物解』 is perfuming cloth incense (熏衣香), which establishes that Silla performed perfuming clothes at that time. During the Goryeo dynasty, Goryeo exported musk as well as ginseng. The royal family burned incense from the Song royal family. Noblewomen preferred sachets. The use of this dress continued into the Joseon dynasty. 『買新羅物解』 showed that Japan imported incense from Silla. 『The tale of Genji』 illustrates Heian nobles' incense culture, perfuming clothes culture, and trade of incense. Perfuming clothes tools became essential articles for marriage purposes and it developed in a practical shape. The Champa had a perfuming clothes culture. It is described on 『諸蕃志』. As Agilawood is found in Tongking, and Tongking was neighbor to the Champa and China, they might have had a perfuming clothes culture as well. Korea, China, Japan, and Vietnam shared a perfuming clothes culture. We can identify universality and commonality in the purpose of perfuming clothes, time of development, the method of making the incense mixture for perfuming clothes, the method of perfuming clothes, the tools, the gender of perfumer, and the type of herbs and spices.