• 한국건설순환자원학회논문집
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• 제5권4호
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• pp.114-121
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• 2010

포틀랜드 시멘트 제조 시 다량의 이산화탄소를 배출함으로써 많은 문제가 발생하고 있다. 그리고 화력발전소 및 제철소의 산업부산물인 플라이애쉬 및 고로슬래그 미분말은 시멘트와 일부 대체하여 콘크리트로 일부 재활용되고 있으나, 42% 정도를 해안 및 육상에 매립함으로써 환경적인 문제를 유발하고 있다. 최근 결합재로 시멘트를 사용하지 않은 알칼리 활성 콘크리트에 대한 연구가 활발히 진행되고 있다. 결합재로 플라이애시 또는 고로슬래그 미분말을 단독으로 사용한 연구는 많으나, 이들 결합재의 혼합사용에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 시멘트를 전혀 사용하지 않고 결합재로서 플라이애쉬와 고로슬래그 미분말을 혼합한 알칼리 활성 콘크리트를 개발할 목적으로 결합재의 혼합비율 및 양생온도가 알칼리 활성 모르터의 시공성, 압축강도 등 특성에 미치는 영향에 대해 검토하였다. 그 결과, 플라이애쉬와 고로슬래그 미분말의 혼합비는 시공성 및 강도에 큰 영향을 주지만, 양생온도는 비교적 큰 영향을 주지 않는 것으로 나타났다. 플라이애쉬와 고로슬래그 미분말을 50%씩 혼합하고, 9M NaOH과 쇼듐실리케이트를 1:1의 비율로 제조한 알칼리 활성화제를 사용할 경우에는 $20^{\circ}C$의 상온양생에서도 재령 28일에서 압축강도 65 MPa의 알칼리 활성 모르터를 제조할 수 있는 것으로 나타났다.

• Toxicological Research
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• 제29권2호
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• pp.121-127
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• 2013

Nanotoxicological research has shown toxicity of nanomaterials to be inversely related to particle size. However, the contribution of agglomeration to the toxicity of nanomaterials has not been sufficiently studied, although it is known that agglomeration is associated with increased nanomaterial size. In this study, we prepared aerosols of nano-sized carbon black by 2 different ways to verify the effects of agglomeration on the toxicity and deposition of nano-sized carbon black. The 2 methods of preparation included the carbon black dispersion method that facilitated clustering without sonication and the carbon black dispersion method involving sonication to achieve scattering and deagglomeration. Male Sprague-Dawley rats were exposed to carbon black aerosols 6 hr a day for 3 days or for 2 weeks. The median mass aerodynamic diameter of carbon black aerosols averaged $2.08{\mu}m$ (for aerosol prepared without sonication; group N) and $1.79{\mu}m$ (for aerosol prepared without sonication; group S). The average concentration of carbon black during the exposure period for group N and group S was $13.08{\pm}3.18mg/m^3$ and $13.67{\pm}3.54mg/m^3$, respectively, in the 3-day experiment. The average concentration during the 2-week experiment was $9.83{\pm}3.42mg/m^3$ and $9.08{\pm}4.49mg/m^3$ for group N and group S, respectively. The amount of carbon black deposition in the lungs was significantly higher in group S than in group N in both 3-day and 2-week experiments. The number of total cells, macrophages and polymorphonuclear leukocytes in the bronchoalveolar lavage (BAL) fluid, and the number of total white blood cells and neutrophils in the blood in the 2-week experiment were significantly higher in group S than in normal control. However, differences were not found in the inflammatory cytokine levels (IL-$1{\beta}$, TNF-${\alpha}$, IL-6, etc.) and protein indicators of cell damage (albumin and lactate dehydrogenase) in the BAL fluid of both group N and group S as compared to the normal control. In conclusion, carbon black aerosol generated by sonication possesses smaller nanoparticles that are deposited to a greater extent in the lungs than is aerosol formulated without sonication. Additionally, rats were narrowly more affected when exposed to carbon black aerosol generated by sonication as compared to that produced without sonication.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.939-942
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• 2007

Vacuum cleaner is a close life product that can remove various dusts from our surroundings. However well vacuum cleaner clean our environments, many people are looking away from it, due to its loud noise. Its noise causes a big trouble in the usual life, for example, catch calls, TV watching and discussing etc. To reduce these inconveniences, noise reduction methods and systematic design of low noise vacuum cleaner are studied in this paper. At first, sound quality investigation is performed to get the noise level and quality that make people TV watching and catch calls available. Based on the European and domestic customer SQ survey result, sound power, peak noise level and target sound spectrum guideline are studied and introduced. As a second, precise product sound spectrums are designed into each part based on the sound quality result. Fan-motor, brush, mainbody, cyclone spectrums are decided to get the final target sound based on the contribution level. Fan-motor is the major noise source of vacuum cleaner. Specially, its peak sound, RPM peak and BPF Peak, cause the people nervous. To reduce these peak sounds, high rotating impeller and diffuser are focused due to its interaction. A lot of experimental and numerical tests, operation points are investigated and optimization of flow path area between diffusers is performed. As a bagless device, cyclones are one of the major noise sources of vacuum cleaner. To reduce its noise, previous research is used and adopted well. Brush is the most difficult part to reduce noise. Its noise sources are all comes from aero-acoustic phenomena. Numerical analysis helps the understanding of flow structure and pattern, and a lot of experimental test are performed to reduce the noise. Gaps between the carpet and brush are optimized and flow paths are re-designed to lower the noise. Reduction is performed with keeping the cleaning efficiency and handling power together and much reduction of noise is acquired. With all above parts, main-body design is studied. To do a systematic design, configuration design developments technique is introduced from airplane design and evolved with each component design. As a first configuration, fan-motor installation position is investigated and 10 configuration ideas are developed and tested. As a second step, reduced size and compressed configuration candidates are tested and evaluated by a lot of major factor. Noise, power, mass production availability, size, flow path are evaluated together. If noise reduction configuration results in other performance degrade, the noise reduction configuration is ineffective. As a third configuration, cyclones are introduced and the size is reduced one more time and fourth, fifth, sixth, seventh configuration are evolved with size and design image with noise and other performance indexes. Finally we can get a overall much noise level reduction configuration. All above investigations are adopted into vacuum cleaner design and final customer satisfaction tests in Europe are performed. 1st grade sound quality and lowest noise level of bagless vacuum cleaner are achieved.

• 자원리싸이클링
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• 제19권4호
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• pp.19-28
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• 2010

산업부산물인 플라이애시 및 고로슬래그는 시멘트와 일부 대체하여 콘크리트로 일부 재활용되고 있으나, 50% 이상을 해안 및 육상에 매립함으로써 환경적인 문제를 유발하고 있다. 최근 결합재로 시멘트를 사용하지 않은 알칼리 활성 콘크리트에 대한 연구가 활발히 진행되고 있다. 결합재로 플라이애시 또는 고로슬래그를 단독으로 사용한 연구는 많으나, 이들 결합재의 혼합사용에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 시멘트를 전혀 사용하지 않고 결합재로서 플라이애시와 고로슬래그를 혼합한 알칼리 활성 콘크리트를 개발할 목적으로 결합재의 혼합비율, 알칼리 활성화제의 종류 및 양생온도가 알칼리 활성 모르타르의 시공성, 압축강도 등 특성에 미치는 영향에 대해 검토하였다. 그 결과, 플라이애시와 고로슬래그의 혼합비와 알칼리 활성화제의 종류는 시공성 및 강도에 큰 영향을 주지만, 양생온도는 비교적 큰 영향을 주지 않는 것으로 나타났다. 플라이애시와 고로슬래그를 50%씩 혼합하고, 9M NaOH과 쇼듐실리케이트를 1:1의 비율로 제조한 알칼리 활성화제를 사용할 경우에는 $20^{\circ}C$의 상온양생에서도 재령 28일에서 압축강도 65 MPa의 알칼리 활성 모르타르를 제조할 수 있는 것으로 나타났다.

• 한국대기환경학회지
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• 제24권6호
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• pp.682-692
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• 2008

Fine particles ($PM_{2.5}$) were collected and analyzed from November 2005 through August 2007 in Chuncheon, Korea to investigate the characteristics of $PM_{2.5}$ and its ionic constituents. The average $PM_{2.5}$ concentration during the study period was $39{\mu}g/m^3$, which is almost two times higher than the annual US NAAQS $PM_{2.5}$ standard of $15{\mu}g/m^3$. $PM_{2.5}$ concentrations were higher in spring and winter than in summer and fall. During spring, Asian Dust events dramatically enhanced $PM_{2.5}$ concentrations, and long-range transport of $PM_{2.5}$ emitted in industrial area of China often occurred during winter based on trajectory analysis. Contribution of $PM_{2.5}$ to $PM_{10}$ concentrations ranged from $72{\mu}g/m^3$ during Asian Dust events to $457{\mu}g/m^3$, indicating that a large portion of $PM_{2.5{\sim}10}$ was transported from China during Asian Dust events. Among the major ionic constituents ${SO_4}^{2-}$ showed the highest concentration, followed by ${NH_4}^+$, ${NO_3}^-$ and ${NO_2}^-$. Chuncheon appeared to be ${NH_4}^+$ rich environment, indicating that $(NH_4)_{2}SO_4$ and ${NH_4}{NO_3}$ were the predominant forms of ${NO_3}^-$ and ${SO_4}^2$ in $PM_{2.5}$. Haze has frequently occurred in Chuncheon since So-Yang dam was constructed in 1973. Haze events were observed on 23 days during sampling period, and the average $PM_{2.5}$ concentration was approximately 1.6 times higher during haze events than during non-haze events. This result suggests that haze enhances the secondary aerosol formation because the aerosol spontaneously absorbs water to form a saturated salt solution, deriving a significant increase in the mass of the particle.

• 한국대기환경학회지
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• 제33권4호
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• pp.411-423
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• 2017

The spacial potential source contribution function (PSCF) method was utilized by considering topography and height of back trajectories based on the measurement of organic typo matter (OM), $NO_3{^-}$, $SO{_4}^{2-}$, and $NH_4{^+}$ at the Baegryungdo Super Site ($37^{\circ}57^{\prime}N$, $124^{\circ}37^{\prime}E$, 135 m a.s.l. (above sea level)) for three selected periods (i.e., January~April, May~August, and September~December) in 2013. The PSCF were calculated on the contributions of trans-boundary transport to the hourly mean concentrations using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The cluster analysis using back trajectories was performed to identify the major airflows to the sampling site. The upper atmosphere in the Tianjin area of China and the lower atmosphere in the western coast area of Korea can be the major source of trans-boundary pollution to the sampling site during January~April resulted from PSCF. The area in Lianyungang-city and Liaoning-sheng, China can be responsibile for the nitrogen related secondary compounds during May~August, and Shandong Peninsula in China is the major source area during September~December. In addition, relationships between the cluster analysis of back trajectories and PSCF were investigated for the statistically significance level for the source areas.

• 폴리머
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• 제24권2호
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• pp.268-275
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• 2000

고전기장을 이용하여 제조한 도전성 탄소섬유/폴리에틸렌 복합필름에 있어서 고분자 점착하층의 두께가 제조된 필름의 체적비저항과 인장강도에 미치는 효과에 대하여 연구하였다. 탄소섬유(CF) 함량과 CF 층밀도에 따라 제조된 필름의 체적비저항과 인장강도의 점착하층에 대한 의존성의 양상은 복잡하게 나타났다. 이는 점착하층의 증가에 따라서 필름 하층면에 중심부나 위쪽에 비하여 CF 농도가 낮은 절연성 고분자층의 두에가 증가하고 필름 상층면 근처에서는 CF의 함침에 필요한 고분자 매트릭스의 양이 적어져 매트릭스 함침이 불충분하여 기공이 포함된 구조를 형성시키는 효과와 증가된 매트릭스의 유동성을 바탕으로 CF 분산성이 향상되고 동시에 보다 치밀한 구조가 형성되는 두 가지 상반되는 효과의 상대적 기여 정도의 차이를 통하여 설명할 수 있었다. 이들 결과는 전자파 차폐용 고도전성 고분자 차폐필름의 제조에 있어서 전기적 성질과 기계적 성질의 최적화하는데 중요하다.

• 한국환경보건학회지
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• 제37권1호
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• pp.29-43
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• 2011

The seasonal characteristics of atmospheric particulate matter (PM) were evaluated through the measurement of $PM_{10}$ (particles with an aerodynamic diameter of less than 10 ${\mu}m$) and $PM_{2.5}$ (particles with an aerodynamic diameter of less than 2.5 ${\mu}m$) collected in the downtown area of Iksan city over roughly two weeks in each season of 2004. During the sampling period, 54 samples of $PM_{10}$ and $PM_{2.5}$ were collected and then measured for mass concentrations of PM and its water-soluble inorganic ion species. The concentrations of $PM_{10}$ and $PM_{2.5}$ were highly variable on a daily time scale in all seasons, especially in fall. Annual concentrations of $PM_{10}$ and $PM_{2.5}$ were $54.7{\pm}21.6\;{\mu}g/m^3$ and $34.0{\pm}13.4\;{\mu}g/m^3$, respectively. The daily concentrations of the analyzed ions similarly showed a pronounced variation, although a difference between seasons existed. Among them, $SO_4^{2-}$, $NO_3^-$ and $NH_4^+$ were the most abundant ions in all seasons, contributing up to 32% of $PM_{10}$ and 39% of $PM_{2.5}$. The contribution of $SO_4^{2-}$ and $NO_3^-$ showed a seasonal variation, as $SO_4^{2-}$ was the highest during spring and summer and $NO_3^-$ was the highest during fall and winter. Non-seasalt $SO_4^{2-}$ and $NO_3^-$ were found to exist mainly as neutralized chemical components of $(NH_4)_2SO_4$ and $NH_4NO_3$ due to the high concentration of $NH_4^+$ in PM samples, which were a major form of airborne PM in all seasons. Seasonal characteristics of $PM_{10}$ and $PM_{2.5}$ in Iksan were described in relation to the temporal variations of daily concentration of PM and its inorganic ion species including inter-particle reactions.

• 대한간호학회지
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• 제4권1호
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• pp.107-120
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• 1974

Necessity and purpose of this study: In a large number of countries it has been founded that children′s domestic accidents are at great risk year by year In the United States, they publish detailed accident statistics at regular intervals. In Korea. there have been just a few studies on Accidents-At-Home of preschool children. But it can not be said that there have been any systematic statistics about this area. and any study accounting for the relations of home accidents and preschool: children in detail, Therefore, the purpose of this thesis was focused on the inquire of these relations so as to make a little contribution to Korean preschool children′s health and security measures. So, the detail-purposes are to study following questions and to testify following hypothesis. Prob. 1. What the types of accidents of Preschool children, where the place accidents occurred\ulcorner Prob. 2. What the cause of accidents and, the main factors of the cause\ulcorner Prob. 3. How about the number of their children. the disparity of age among their children and mother′s age in each case of accidents\ulcorner hypothesis 1. There will be differences in the density of protection of parents according to the number of their children. hypothesis 2, There will be differences in accident-types and first-aid methods according to parents socio-economic background. Method; This study employed the interviewing survey method, in which 130 preschool children ware random.sampled, who visit hospital to have medical care. These children (from 1 to 6 years olds) were selected at the emergency room of five hospitals in Seoul (Hosp: Severance, Woosok, Medical Center, Hanyang Medical College Hospital and Seoul Medical Col1age Hospital during study-period (from Aug. to Oct, 1973). Four head nurses in above Hospitals were employed as accident members for this study. Concerning research analysis, the method of hypothesis verifying is used. Conclusion: As two American experts on this subject. Dr, Raymond Neuter and Mr. Ross Mc Garland have drawn attention to "minor epidemics of accidents" that could be avoided by fairly simple measures. preschool children′s accidents could be avoided by parents fair attentions. In other words, one of the most common causes of preschool children′s accidents derived from their parent′s inattention. Therefore, one important task on this subject is to instruct the parents fairly about the children′s accidents. Many accidents could be avoided by the exorcist of a little self-discipline. Also, as much the prevention of accidents is important, as the first-aid Is Important and necessary at the case of the accidents. So, the methods of proper first-aid treatment must be emphasized, and must be taught in school, especially in girls school. And there could be other means available for prevention of accidents. Firstly, the public authorities can take legal measures. More stringent safety standards can be made enforceable by law. Building materials and equipment for domestic us: ought to meat minimum safety criteria at all times. Next the public itself has to understand the seriousness of the problem, and here the dissemination of information is of great importance. All mass media should be brought into play to promote greater public awareness of the question. At last, it will be needed to obtain more detailed epidemiological data through additional surveys and statistics after this study.

• 대한간호학회지
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• 제24권4호
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• pp.678-695
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• 1994

The purpose of this study was to investigate knowledge, attitudes and practices of women toward breast self-examination and to identify factors that may influence compliance with breast examination. The subjects for this study were 282 women in three hospitals located in In-Chun. Data were collected during the period from October 15 to 30, 1993 by means of a structured questionnaire. The data were analyzed using the SAS program and include descriptive statistics, 1-test, ANOVA, Pearson correlation coefficient and stepwise multiple regression. The results of study are as follows : 1. The mean knowledge score for the total sample was 13.58. Factors affecting the women's knowledge of breast cancer and BSE were : age, level of education, experience with breast cancer patients, experience in learning BSE, information about BSE, self-practice of BSE, level of intention to perform BSE, and participation in a BSE class. 2. Elements related to attitude included : (a) perceived feeling of susceptibility to breast cancer, and (b) belief about the effectiveness of BSE. The mean perceived susceptibility score was 1.62 and the mean effectiveness score was 4.22. Factors affecting the women's perceived susceptibility to breast cancer were exercise for health, level of intention to perform BSE , intention to recommend to others and self-practice of BSE. The relation between the womens' belief about effectiveness of BSE and level of intention to perform BSE and intention to recommend to others were statistically significant. 3. The mean self-practice score for the total sample was 4.01. Factors affecting the women's practice were experience with breast cancer patients, information about BSE, experience in learning BSE, enlisting the help of significant peers, and level of intention to perform BSE. Results indicated 35.8% of the total sample practiced BSE. The most frequent reason women gave for not performing BSE was “Didn’t knew about BSE technique”, “Didn’t think do it”. 4. No relation was found between knowledge and attitudes and practices. 5. When all the variables were examined for their contribution to the variance in the practice of BSE, it was found that confidence in ability to detect a mass by BSE, knowledge about breast cancer and BSE, and experience with breast cancer patients were significant variables and explained 35.8% of the variance. From the results of this study it can be said that women need to be taught proper BSE technique so they can become more proficient in detecting breast abnormalities.