• Safety and Health at Work
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• 제15권2호
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• pp.181-186
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• 2024

Background: This study aimed to analyze the trend of occupational noise-induced hearing loss (ONIHL) in Brazilian workers at a metallurgical plant with a hearing conservation program (HCP), which has been addressed in a previous study. Methods: All 152 workers in this time series (20032018) participated in the HCP and used personal protective equipment. All annual audiometry records in the company's software were collected from the electronic database. The trend of ONIHL was analyzed with the joinpoint regression model. The hearing thresholds of ONIHL cases at the end of the series were compared with those found in a national reference study. Results: The binaural mean hearing thresholds at 3, 4, and 6 kHz at the end of the series were higher for ages ≥50 years, exposures ≥85 dB (A), time since admission >20 years, and maintenance workers. Significance was found only in the group divided by age. There was an increasing time trend of ONIHL, though with a low percentage variation for the period (AAPC = 3.5%; p = 0.01). Hearing thresholds in this study differed from the reference one. Conclusion: Despite the unmet expectation of a stationary trend in the study period, the time pace of ONIHL evolution did not follow what was expected for a population exposed to noise. These findings signal to the scientific community and public authorities that good ONIHL control is possible when HCP is well implemented.

• Asian-Australasian Journal of Animal Sciences
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• 제22권1호
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• pp.42-48
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• 2009

An in vitro incubation study was conducted to investigate effects of 2-bromoethanesulfonic acid (BES) on ruminal fermentation characteristics and methanogen population. BES at the final concentration of 0, 1 and 5 mM with two different substrates having a different ratio of timothy and concentrate (100% timothy vs. 40% timothy-60% concentrate) was incubated for 0, 24, 48 and 72 h in a $39^{\circ}C$ incubator. Total DNA extracted from culture fluid was used as a template for real-time PCR to measure the population of methanogens. Four different primer sets were used for amplification of total bacteria, total methanogens, the order Methanobacteriales and the order Methanomicrobiales. BES reduced (p<0.01) total gas and methane production in a dose-dependent manner. BES at 5 mM inhibited methane production by more than 95% compared to the control. An interaction between substrate and level of BES in total gas and methane was detected (p<0.01). The decrease of methane production with increasing BES level was more pronounced on mixed substrate than on timothy alone. However, hydrogen production was increased by BES treatment (p<0.01). Total VFA concentration was not affected, but molar percentage of propionate and butyrate was increased and acetate to propionate ratio was reduced by BES treatment (p<0.01). BES did not affect the population density of total bacteria but reduced (p<0.01) the population of total methanogens, the order Methanobacteriales and the order Methanomicrobiales in a dose-dependent manner. The type of substrate did not influence the trend, although the magnitude of response was different between all-roughage and 40% roughage substrate.

• 한국응용곤충학회지
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• 제39권3호
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• pp.141-147
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• 2000

봄재배 국화에서 아메리카잎굴파리 성충은 5월 상순부터 황색 끈끈이트랩에 유인되기 시작하여 7월중순까지는 발생량이 많고 7월하순부터 수확기까지는 비교적 밀도가 낮았고 가장 발생량이 많은 시기는 6월중순~하순이었다. 유충의 밀도는 5월하순부터 서서히 증가하기 시작하여 7월상순에 가장 높았고 이후부터는 급격히 감소하여 절화를 생산하는 시기에는 밀도가 가장 낮았다. 가을재배에서는 봄재배에 비하여 셩충의 유인수는 비교적 낮은 수준이었으나 9월하순 10월중순에 유인량이 비교적 많았고 유충의 밀도변화도 수확기까지 성충과 비슷한 경향이었다. 정식후 국화 생장에 따른 피해엽율의 변화는 봄재배에서 4주째부터 피해엽이 나타나지 시작하였으며 5주째까지는 피해엽율이 비교적 낮았으나 6주째부터는 70% 이상으로 급격히 증가하여 수확기까지 계속되었다. 국화 품종에 따른 아케리카잎굴파리에 의한 피해엽율은 대국에서는 수방력이 초기에 피해가 약간 낮게 나타났지만 후기에는 조사된 모든 품종에서 45% 수준으로 높았고, 소국에서는 사티니스가 21.3%로 리건, 카산드라 등의 50% 수준보다 낮았다. 본 시험에서 검정된 국화품종은 모두 국화의 생장과 함께 피해엽이 증가하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권22호
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• pp.9899-9903
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• 2014

Nasopharyngeal carcinoma (NPC) is an uncommon disease in most countries but occurs with much greater frequency in southern China. This study aimed to examine the secular trends of NPC in urban Guangzhou over the time period of 2000-2011 using data from the Guangzhou Cancer Registry. Age-adjusted annual incidence rates of NPC were calculated by the direct method using the WHO World Standard Population (1960) as the reference. The average annual percentage change (AAPC) was used as an estimate of the trend. A total of 7,532 new cases of NPC and 3,449 related deaths were registered. In both genders, the peak incidence occurred in the 50- to 59-year age group, and this age distribution pattern remained similar throughout. The AAPC in NPC incidence rates was -3.26% (95% CI: -5.4%--1.1) for males and -5.74% (95% CI: -8.9%--2.5) for females, resulting in a total decrease of 39.3% (from 22.14 to 13.44 per 100,000 population) for males and 48.6% (from 10.1 to 5.18 per 100,000 population) for females over this 12-year period. The AAPCs in NPC mortality rates were -4.62% (95%CI: -3.5%--5.7) for males and -6.75% (95% CI: -5.2%--8.3) for females, resulting in a total decrease of -46.1% (from 12.1 to 6.54 per 100,000 population) for males and 51.7% (from 4.14 to 2.00 per 100,000 population) for females. The age-adjusted incidence and mortality rates of NPC declined during 2000-2011 in urban Guangzhou but remained high. Future efforts to improve prevention, early detection and treatment strategies are needed.

• 환경위생공학
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• 제16권3호
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• pp.22-27
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• 2001

It have been investigated how algal and bacterial symbiotic reaction influences on removal of organic carbon in river ecosystem. And artificial experimentation apparatus was made for algae'and bacteia'culture as lab scale. Investigating and researching minutely the change of concentration of organic carbon substrate and the change of population density of algae'and of bacteria'with this artificial experimentation apparatus, the next results could be obtained. 1. Successful decrease of DOC(dissolved organic carbon) could not be expected unless algal and bacterial biomass floe was nut formed effectively and unless biosorption was not proceeded effectively in the very culture system in which artificial synthetic wastewater was supplied continuously at constant rate. 2. In conditions of culture liquid of 1335 glucnse mg/L(type 1) and of 267 glucose mg:L(type 2), the algal dominant species was always Chlorella vulgaris in both types in which artificial synthetic wastewater were supplied continuously at constant rate and algae population density was around maximum 107 cells/mL. 3. It was around 108 ~ 107 cells/mL that the population density of heterotrophic bacterium. In culture medium systems type 1 and type 2 in which artificial wastewater were supplied continuously at constant rate, the same density appeared initially when using the population density of Escherichia coli w 3110 as indirect indicator. And this density decreased rapidly till the culturing date 35 days were passed away, while this density increased with gentle slope after same date and then the trend of change at type 2 was more severe than one at type 1. 4. When seeing such a change of population density of Escherichia coli w 3110, the growth of heterotrophic bacterium appeared as survival instinct pattern of broader requirement of nutrient at condition of low concentration of organic carbon substrate than condition of high concentration of same substrate.

• 한국인구학
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• 제18권2호
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• pp.70-97
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• 1995

이 논문은 지난 반세기동안 북한에서 이루어진 도시화의 추세와 그 특징을 분석하기 위한 것이다. 이를 위해 우선 분단 이후 행정구역변천의 주요 내용을 개괄하였고, 지역별 인구분포를 살펴보았다. 그리고 도시인구의 변화추세와 도시체계의 특징을 경제발전정책과 관련하여 파악하고자 노력하였다. 북한에서는 6.25 전쟁 종료 이후 중공업 위주의 발전정책에 때라 1960년대 말까지 빠른 속도로 도시화가 진행되었으나, 1970년대 초부터 폐쇄적인 경제발전전략이 한계를 드러내면서 도시화의 속도는 현격하게 떨어졌다. 북한의 도시화 과정에 있어서 두드러진 특징은 새로운 도시의 육성전략에 따라 내륙지역의 도시들이 급속히 성장하였고, 중소도시의 인구규모가 꾸준히 증가햐였다는 것이다. 아울러 평양을 비롯한 대도시에서도 도시경계의 확장과 더불어 인구증가가 이루어졌다. 북한의 주요 도시들은 인구규모는 작으나, 외곽에 농업지역을 포함하고 있기 때문에 그 면적은 남한의 대도시들보다 훨씬 더 넓다. 또한 평양이 지니는 사회주의적 종주도시의 성격과 위성도시들의 두드러진 성장도 특징으로 지적될 수 있다. 마지막으로, 이 연구에서는 북한의 이동인구규모와 그 특징, 그리고 통일후에 예상되는 인구이동에 관한 논의도 이루어졌다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.397-399
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• 2007

This paper presents multiple regression analysis and data update to improve present spatial electric load forecasting algorithm of the DISPLAN. Spatial electric load forecasting considers a local economy, the number of local population and load characteristics. A Case study is performed for Jeon-Ju and analyzes a trend of the spatial load for the future 20 years. The forecasted information can contribute to an asset management of distribution systems.

• Communications for Statistical Applications and Methods
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• 제6권2호
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• pp.457-466
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• 1999

Centered modified systematic sampling (CMSS)' was proposed by Kim(1985) for estimating the mean of a population with a linear trend. In the present paper a version of this sampling method is suggested. This version turns out to be efficient in the same degree as the original method from the viewpoint of the expected mean square error criterion. It is also shown to be quite an efficient method as compared with other existing methods. An illustrative example is given.

• Communications for Statistical Applications and Methods
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• 제4권3호
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• pp.743-752
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• 1997

Kim (1985) proposed the so-called "centered balanced systematic sampling" for estimating the mean of a population with a linear trend. In this paper, a version of this sampling method is proposed. It is shown that this version is as efficient as the original method from the viewpoint of the expected mean square error criterion. It is also shown to be quite an efficient method as compared with other existing methods.g methods.

• 한국환경보건학회지
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• 제49권1호
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• pp.37-47
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• 2023

Background: Paraben is a widely used substance with a preservative effect found in various materials such as food, medicine, personal care products, and cosmetics. Objectives: This study was conducted to identify the level of urinary paraben concentrations (i.e., methyl-, ethyl-, and propyl-) among Korean adults and to explore the factors related with the exposure levels. Methods: We analyzed the third period (2015~2017) of the Korean National Environmental Health Survey (KoNEHS). R statistical software (version 4.1.1) was used to estimate representative values for the whole population with weight variables to reflect sampling design. Whether urinary concentrations tended to increase as the level of paraben exposure-related characteristics increased was tested and P_trend was calculated using general linear models. Results: Urinary concentrations of all three parabens (i.e., methyl-, ethyl- and propyl-) were higher in women than in men (P_trend<0.0001, 0.008, and <0.0001), and the values of methylparaben and propylparaben tended to increase as the age of subjects increased (P_trend<0.0001, and <0.0001). Urinary concentrations of methylparaben and propylparaben were associated with intensity of exercise (P_trend<0.001, and 0.004), and that of propylparaben was higher in non-smokers (P_trend=0.01). In terms of paraben exposure-related variables, urinary concentrations of parabens (i.e., methyl-, ethyl- and propyl-) increased as the daily average frequency of teeth-brushing (P_trend<0.0001, 0.03 and 0.0001), the frequency of use of hair products (P_trend=0.005, 0.05 and 0.04), the frequency of use of makeup products (P_trend<0.001, 0.001 and <0.001), and the frequency of use of antibacterial products (P_trend=0.005, 0.02 and 0.02) increased. Conclusions: In our study, urinary concentrations of all three parabens are associated with gender, teethbrushing, hair products, make-up products, and antibacterial products. Methyl- and proyl-parabens were associated with age and intensity of exercise, and propyl-paraben was associated with smoking.