• 한국환경농학회지
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• 제17권3호
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• pp.234-238
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• 1998

Anaerobic degradation characteristics of dewatered liquid of household food waste including methane conversion efficiency and degradation kinetics were studied in an anaerobic batch reactor of 5 L volume. The ultimate methane production for dewatered liquid of household food waste tested was over 0.31L $CH_4/L{\cdot}dewatered$ liquid of household food waste. The kinetic constant of dewatered liquid of household food waste tested was $0.223d^{-1}/L$. The kinetic behavior of anaerobic degradation was described as a first order series reaction. The determinant of rate-limiting step(DR) that is balanced out from the rates of reaction steps was defined by the logarithmic difference of the maximum acidification rate and the maximum methanation rate. Anaerobic degradation characteristics of organic materials were evaluated by the value of DR. The DR of dewatered liquid of household food waste tested was 1.17.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.740-746
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• 2010

Most important characteristics of calcareous sand are the particle angularity and hollow structure. These characteristics lead to the different behavior of calcareous sand compared to siliceous sand. This study performs a series of dilatometer test using calibration chamber, in order to analyze the effect of particle characteristic of calcareous sand on DMT indices. From experimental test, it is observed that the horizontal stress index($K_D$) and dilatometer modulus($E_D$) of calcareous Jeju sand is underestimated compared to siliceous sand. This is because the particle crushing during penetration induces the less contraction of the dilatometer membrane. A slightly smaller influence of particle crushing is reflected in $E_D$ rather than $K_D$, because $P_1$ pressure reflects the deformation characteristics of un-crushed particle relatively well. It is also observed that $K_D$ of Jeju sand is differently influenced by the vertical effective stress compared with that of siliceous sand.

• 한국환경보건학회지
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• 제28권4호
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• pp.12-16
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• 2002

Workers' exposure to lead particles with diverse characteristics was assessed using personal cascade impactors in four different industries. Correlation analyses found that total airborne lead (PbA) concentrations could not explain the variation on MMAD of lead particles. From regression analysis, the concentrations of lead particles smaller than 1 um in AD were found to rise very slowly with increases in total PbA. They rarely contributed more than 50 ㎍/㎥ of total PbA over the range of 5.6-7,740 ㎍/㎥ although there are a few high values greater than 100 ㎍/㎥ while respirable lead concentrations significantly increased with increasing total PbA concentrations. In the secondary smelting and radiator manufacturing industries requiring high temperatures, the average fraction of respirable concentration in total PbA was 43.3% and 48.9%, respectively, which indicated an important contribution to the total PbA. In lead powder and battery manufacturing, it was less than 27%. Our study results concluded that workers' exposure to lead particles with diverse characteristics might not be effectively monitored by the current total PbA sampling alone. To protect workers exposed to different sizes of lead particles generated in many operations, an occupational standard for respirable lead particles should be added to the current total lead standard.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_2호
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• pp.89-95
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• 2001

The solidification and leaching characteristics of cyclone ash collected from an industrial incineration plant were investigated. Cement and calcium hydroxide were used as the solidifying materials. The leaching characteristics of the solidified cyclone ash were found to vary depending on both the quantitative and the qualitative aspects of the solidifying materials. Except for copper and lead, all the heavy metal ions in the leachate of the solidified material composed of 10~20 % cement or 10~20 % calcium hydroxide were found to be within their standard limit. Moreover, all the heavy metal ions were also observed to be within satisfactory limits in the leachate obtained from the solidified material composed of 30 % cement or 30 % calcium hydroxide. Therefore, to satisfy the standard compressive intensity and permissible limits of heavy metal ions leached from solidified material, it would appear that a 30 % proportion of either additive in the solidification product can meet the required standard for the leachate. The cost of solidifying cyclone ash per ton for ash-30 % cement and ash-30 % lime was calculated as 26,750 and 26,070 won, respectively. Accordingly, significant reduction in the waste toxicity and mobility as well as an improvement in the engineering properties of the solidified products were successfully achieved.

• 한국의류산업학회지
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• 제24권6호
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• pp.756-765
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• 2022

The purchase-related responses of MZ generation consumers may vary depending on the environmental factors of the fitting room. Therefore, this study extracted and systematized fitting room characteristics in the retail fashion environment. In-depth interviews were conducted with a total of 50 informants to collect data on the experience of using the fitting room. Then, a qualitative analysis was performed. First, results confirmed that the environmental factors of the fitting room include physical (spatiality, functionality, comfort, and convenience) and human (interactivity and congestion) aspects. Next, additional analysis was performed on functionality and interactivity to clarify the influence of environmental characteristics of the fitting room. These factors were classified into qualitative categories. The study results confirmed that, in the case of functionality, preferred lighting and mirror factors vary depending on the clothing product type, the place and situation for wearing, and individual characteristics. Furthermore, regarding interactivity, the preference for the presence of sales staff or companions differed according to personal traits and the need for additional information and evaluation. The study provides valuable information for effective fitting room space planning for offline fashion stores to meet the needs of MZ generation consumers.

• Membrane and Water Treatment
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• 제15권1호
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4554-4560
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• 2023

Continuous monitoring of radioactive substances over a prolonged duration can yield crucial insights into the levels of radiation exposure through inhalation, both in the vicinity of nuclear facilities and/or general environments. In this study, we evaluated long-term measurements (2012-2022) of gross alpha-beta activities in the air in the vicinity of nuclear facilities and reference site, distribution characteristics of temporal trends and spatial fluctuations, and factors affecting radioactivity levels. The average airborne gross-α (in mBq m^-3) for onsite and off-site were 0.124 and 0.117, respectively, and the average airborne gross-β (in mBq m^-3) measurements were 1.10 and 1.04, respectively. The activity ratio (AR) of gross-α and gross-β were calculated as a ratio of 0.12. The distribution characteristics of gross-α and gross-β activities in this study area are likely influenced by the meteorological factors and variations in airborne PM concentrations rather than the operation of the nuclear facility.

• 미생물학회지
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• 제30권3호
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• pp.193-198
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• 1992

낙동강 하구언 건설에 따른 하구생태계의 변화를 파알하기 위하여 축조 전후의 환경인자와 종속 영양세균의 생리적 특성을 요인분석에 의해 비교하였다. 하구언 축조 후 해수유입의 영향이 급격히 감소하였으며, 축조 전 50.7% 를 차지하던 영양물질의 과다와 관련된 환경변수가 축조후 77.1%로 증가하였다.하구언 축조 전 환경변수와 종속영양세균의 생리적 특성 사이에 밀접한 관련성을 나타냈으며, 축조 후에도 종속영양세균의 생리적 특성이 영양물질의 과다와 관련된 형질로 대부분 해석되어 환경변화와 분포 미생물의 생리적 특성 사이의 관련성을 나타내었다. 그러나 하구언 축조에 따른 해수유입의 차단에도 불구하고 분리균주의 생리적 특성에 의한 요인분석의 3번째 쥬요인이 호염성 형질로 해석되어 작동강 하구의 환경변화에 따른 종속영양세균의 형질이 아직 완전 안정화되지 않은 것으로 사료된다.

• 한국환경과학회지
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• 제25권7호
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• pp.1007-1016
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• 2016

Environmental policy implementation has been strengthened to protect the source waters in Korea and to improve their water quality. Increasing of non-point source caused water quality problem continuously. Research on runoff from forests, which occupy over 65% of the land in korea, is insufficient, and studies on the characteristics and influences of storm runoff are necessary. In this study, we chose to compare the effects of land use in the form of two types of forest distribution and then gathered data on storm characteristics and runoff properties during rainfall events in these areas. Furthermore, the significance and influences of the discharges were analyzed through correlation analysis, and multilateral runoff characteristics were examined by deducing a formula through $COD_{Mn}$ and TOC regression analysis. At two forest points, for which the basin areas differed from each other, flow changed according to storm quantity and intensity. The peak discharge at point A, where the basin area was big, was high, whereas water-quality fundamental items (BOD, $COD_{Mn}$, and SS) and TOC density were high at point B where the slope and storm intensity were high. Effects of dissolved organic matter were determined through correlation analysis, and the regression formulas for $COD_{Mn}$ and TOC were deduced by regression analysis. It is expected that the data from this study could be useful as basic information in establishing forest management measures.

• 한국융합학회논문지
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• 제8권6호
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• pp.171-180
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• 2017

본 연구는 중등학생의 융합교육 실행자인 중등교사의 개인특성, 환경특성이 교사효능감과 직무만족도에 미치는 영향을 검증하고자 수행되었다. 이를 위해 광주 전남 지역의 55개 중등학교 남녀 교사 696명을 대상으로 교사효능감과 직무만족도 검사 실시 후, 그 결과를 분석하였다. 본 연구에서 교사효능감은 소명감, 교수학습, 동료관계, 학교조직의 4가지 요인으로, 직무만족도는 직무관계, 보상체계, 근무환경의 3가지 요인으로 구성되었다. 다변량 분석결과, 교사의 개인적 특성과 근무환경에 따라 교사효능감과 직무만족도에 의의 있는 차이가 있었다. 따라서 교사효능감과 직무만족도는 교사의 개인특성, 환경특성 등에 의해 형성되는 복합적인 요인으로 볼 수 있다. 중등교사의 교사효능감과 직무만족도 제고를 위해서는 개인특성과 환경특성을 모두 반영한 교사교육과 연수 프로그램 개발 등의 방안 마련이 필요할 것으로 보인다.