• 상하수도학회지
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• 제25권3호
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• pp.391-398
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• 2011

This study is to develop highly efficient coagulation system(HECS) that runs treatment with a short retention time to cover the overflow in the rain, which coagulation, mixing and settling are contacted in a single reactor and to estimate the applicability. Setting up 100ton/day-size pilot scale plant, the results of continuous operation in case of runoff, maintaining 20 minute-retention time at optimum chemical injection condition(Alum 100mg/L, Polymer 1.0mg/L) shows the highest removal efficiency(Turbidity 93.1%, TCODcr 80.6%, BOD 81.8%, SS 92.5%, TN 72.3% and T-P 87.3%). It was estimated that the large amount of cost for separate sewage system and the size of area for system instruction can be reduced if the HECS is applied for CSOs treatment because the HECS is so compact and quickly. When we see the results, HECS from this study could be able to treat the pollutant quickly within a short retention time only with coagulant and polymer, which could show high applicability.

• 대한화학회지
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• 제30권4호
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• pp.352-358
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• 1986

페놀류의 머무름 거동에 대한 실험적 관찰을 이성분용매인 MeOH-Water, ACN-Water, THF-Water와 삼성분용매인 MeOH-Water, ACN-Water, THF-Water계에서 수행했다. 이 머무름 거동의 데이타들로써 용매의 성분비에 따른 크기인자를 예측할 수 있는 선형방정식을 얻었다. 또 페놀류의 최적 분리에 적합한 MeOH-Water이성분 용매를 기준하여 이론적으로 용매세기가 같은 이성분과 삼성분용매를 사용했고 이 등용매세기하에서 시료에 대한 머무름 거동의 특이성 효과는 이성분용매계가 삼성분용매계보다 더 크게 나타났다.

• Geomechanics and Engineering
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• 제33권2호
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• pp.141-154
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• 2023

This study investigated the effect of water retention characteristics between aged and fresh Municipal Solid Waste (MSW) on the stability of the landfill. A series of transient numerical modeling for the slope of an MSW landfill was performed considering the variation of water retention characteristics due to leachate circulation. Four different scenarios were considered in this analysis depending on how to obtain hydraulic conductivity and the aging degree of materials. Unsaturated hydraulic properties of the MSW used for the modeling were evaluated through modified hanging column tests. Different water retention properties and various landfill conditions, such as subgrade stiffness, leachate injection frequency, and gas and leachate collection system, were considered to investigate the pore water distribution and slope stability. The stability analyses related to the factor of safety showed that unsaturated properties under those varied conditions significantly impacted the slope stability, where the factor of safety decreased, ranging between 9.4 and 22%. The aged materials resulted in a higher factor of safety than fresh materials; however, after 1000 days, the factor of safety decreased by around 10.6% due to pore pressure buildup. The analysis results indicated that using fresh materials yielded higher factor of safety values. The landfill subgrade was found to have a significant impact on the factor of safety, which resulted in an average of 34% lower factor of safety in soft subgrades. The results also revealed that a failed leachate collection system (e.g., clogging) could result in landfill failure (factor of safety < 1) after around 298 days, while the leachate recirculation frequency has no critical impact on stability. In addition, the accumulation of gas pressure within the waste body resulted in factor of safety reductions as high as 24%. It is essential to consider factors related to the unsaturated hydraulic properties in designing a landfill to prevent landfill instability.

• 원예과학기술지
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• 제28권4호
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• pp.656-663
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• 2010

노란색 유향성 호접란을 육성하기 위해 황화계 육종모본들을 이용하여 5종류의 교배조합이 작성되었으나 $Phal.$ Brother lawrence를 종자친으로 $Phal.$ Brother saragold를 화분친으로 한 교잡에서만 정상적인 교배와 꼬투리 형성 및 종자발아가 이루어졌다. 잡종후대로 약 500개체가 실생 조직배양을 통해 육성되어 온실에 심어졌으며 개화기에 화색과 화형 위주로 60여 우수개체가 1차 선발 되었고 다시 생육속도, 병충해저항성 등을 검정한 2차 선발에서 15계통이 육성되었다. 이들을 대상으로 향기가 비교적 강하고 꽃 수명이 길어 시장에서 기호도가 높을 것으로 예상되는 6계통을 최종 선발하였다. 최종 선발된 이들 유향종들과 이들 교잡종들의 양친을 대상으로 전자코를 이용한 향기패턴분석이 이루어졌다. 전자코로 꽃 향기를 분석한 후 GC chromatogram peak와 이 피크를 이용한 Polar derivative diagram을 작성 비교한 결과 양친에서는 retention time 7s와 9s 사이, retention time 20s와 25s 사이에서 강한 peak가 나타났다. 양친과 비교하여 잡종후대의 선발계통에서는 retention time 7s와 9s 사이 즉 8s 근처에서 하나의 강한 피크가 공통적으로 나타났으며 양친에서 나타났던 retention time 20s와 25s 사이에서 강한 2개의 피크는 교잡후대 중 4개의 계통에서 이 피크가 강하게 발현되었으나 2개의 계통에서는 오히려 거의 나타나지 않았다. 그리고 $VaporPrint^{TM}$ 이미지 분석소프트웨어를 이용하여 향기패턴을 시각적으로 이미지화 한 결과 더욱 명확하게 향기패턴을 비교 분석할 수 있었는데 마찬가지로 교잡양친과 교잡후대계통 모두에서 retention time 8s 근처에서 강한 peak가 공통적으로 나타났으며 이 피크의 성분은 노란색 유향종에서 주로 강하게 발현되는 향기성분인 것으로 판단되었다. 이 피크는 향후 노란색 유향성 개체의 교잡선발 육종에 유용한 마커로서 활용할 수 있을 것으로 판단되었다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2008년도 제33회 펄프종이기술 국제세미나
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• pp.47-70
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• 2008

Cost efficiency is today the primary requirement in the paper and board industry. This has led therefore, to a greater preponderance of products with specifically designed functionality to take account of current industry needs. Continually increasing machine coating speeds together with these new coating colour components have put more emphasis on the importance of the correct rheology and water retention of the coating colours to achieve good runnability and end product quality. In the coating process, some penetration of the aqueous phase, to the base paper or board must occur to anchor the pre-coating to the base or the topcoat to the pre-coat. The aqueous phase acts as a vehicle not only for the binder, but also for the other components. If this water or material penetration is not controlled, there will be excessive material shift from the coating colour to the base, before immobilization of the coating colour will stop this migration. This can result in poor machine runnability, unstable system and uneven coating layer, impacting print quality. The performance of rheology modifiers or thickeners on the coating color have tended to be evaluated by the term, "water retention". This simple term is not sufficient to explain their performance changes during coating. In this paper we are introducing a new concept of "material retention", which takes note of the total composition of the coating colour material and therefore goes beyond the concept of only water retention. Controlled material retention leads to a more uniform z-directional distribution of coating colour components. The changes that can be made to z-directional uniformity will have positive effects on print quality as measured by surface strength, ink setting properties, print gloss, mottling tendency. Optical properties, such as light scattering, whiteness and light fastness delivery should also be improved. Additionally, controlled material retention minimizes changes to the coating colour with time in re-circulation giving less fluctuation in quality in the machine direction since it more closely resembles fresh coating for longer periods. Use of the material retention concept enables paper and board producers to have more stable runnability (i.e. lower process costs), improved end product quality (i.e. better performance of used chemicals) and/or optimized use of coating colour components (i.e. lower total formulation cost)

• 여성건강간호학회지
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• 제25권3호
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• pp.329-344
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• 2019

Purpose: This study aimed to identify utilization of the work-family support policy (WFSP) and factors affecting retention intention among Korean female military officers. Methods: This cross-sectional survey recruited 103 married female officers from the Korean Army, Navy, and Air force with preschool-aged children through convenience and snowball sampling. Via online surveys from June to November, 2018, the participants self-reported retention intention, work-family conflict, job satisfaction, and utilization of the WFSP. The data were analyzed using descriptive statistics, independent t-tests, one-way analysis of variance, Pearson's correlation coefficient, and multiple linear regression. Results: Retention intention ($22.29{\pm}5.98$) was reported at the mid-level, lower than scores reported in the literature for female workers. Work-family conflict ($32.51{\pm}5.29$) and job satisfaction ($63.10{\pm}7.45$) were above the midpoint levels. Use of maternity leave (100.0%) and parental leave (92.2%) was high, especially compared to the rates of child-care day off (20.4%) and parenting time (20.4%). 'Noticeable increases in childcare services within the army' (22.8%) was reported as the supportive measure needed the most by female military officers. Job satisfaction (${\beta}=.43$, $p{\leq}.001$), the use of parenting time (${\beta}=-0.29$, p=.002), living type (${\beta}=-.18$, p=.043), and service type (${\beta}=-.16$, p=.035) significantly influenced retention intention. Conclusions: The findings highlight the priority areas of importance within the WFSP and suggest that a family-friendly culture can improve female officers' retention intention. Accordingly, policy changes at the Ministry of National Defense improving the system to enhance a family-friendly culture in the military is expected to strengthen the retention intention of female officers and contribute to excellence in the military workforce.

• 한국지구과학회지
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• 제30권6호
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• pp.709-720
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• 2009

보수성 포장재가 지표면 열수지와 중규모 순환장에 미치는 영향을 파악하기 위하여 수치실험과 야외 관측을 실시하였다. 수치실험에 이용된 모형은 LCM(Local Circulation Model)이며, 야외 관측은 대기가 안정되어 날씨가 맑은 2007년 7월 19일 실시되었다. 야외 관측실험에서 보수성 포장재 지표면 온도의 최대치는 1430 LST에서 $41.2^{\circ}C$이고, 보수성 재료가 도포되어 있지 않은 일반 아스팔트보다 $16.1^{\circ}C$ 낮게 관측되었다. 수치실험에서는 증발효율 0.3을 가정한 case BET03에서 관측과 가장 유사한 값을 나타내었다. 이때 현열과 잠열플럭스는 각각 227 와 229 $W/m^2$이다. 수치실험 결과, 보수성 포장재는 낮은 지표면 온도, 혼합고와 관련된 잠열플럭스를 높이는 경향이 나타난다. 보수성 포장재에 의한 잠열플럭스의 불연속은 교외풍과 같은 중규모 순환장의 발달을 강화시키는 역할을 한다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Pre-symposium of the 10th ISWPC Recent Advances in Paper Science and Technology
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• pp.386-389
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• 1999

Amphoteric polymers have brought to papermakers' attention gradually. In this paper, a series of amphoteric starches with different cationic and anionic degree of substitution (DS) are prepared. Better product has been selected and used under different condition. As retention and drainage aids, amphoteric starches were used in shorter fiber length, weak strength and poor drainage bleached AQ-Soda wheat straw pulp. In neutral and alkaline papermaking system, when amphoteric starches contain 0.024-0.026 anionic degree of substitution (DS), it is shown that the higher the cationic degree of substitution (DS) in amphoteric starches, the better the filler retention. The filler retention is improved 12.5%, 30.3%, and 35.1% and 32.5% respectively by adding 1% amphoteric starch LS-L2 -1 (0.034), LS-L2-2 (0.040), LS-L2-3 (0.047) and LS-L2-4 (0.052). But the strength of handsheets if affected a little. By adding 2% Al2 (SO4)3 and 1.5% LS-L2-3 at pH 7.5, filler retention can be improved from 38% to 80%, and breaking length of sheet only decreases 3.2%. As dry strengthening aids, amphoteric starches were used in eucalyptus APMP. Amphoteric starches are used in eucalyptus APMP. The amphoteric starch LS-L2-2 is better dry strength aid. Adding 1% LS-L2-2 can improve breaking length 24.5%, burst index 42.9%, tear index 38.8%, folding endurance and density of the handsheets.

• 공업화학
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• 제17권3호
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• pp.317-320
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• 2006

본 연구에서는 HCI프로그램을 이용하여 여섯 가지 퓨린 유도체(caffeine, guanine, hypoxanthine, purine, theobromine, and theophylline)의 최적 분석 조건을 결정하였다. 이동상으로 물과 메탄올을 사용하는 역상 HPLC를 사용하였다. 체류모델로는 Snyder, Langmuir, Binary polynomial 중에서 체류인자를 가장 잘 예측한 Binary polynomial을 사용하였고 용출곡선을 계산하기 위해서는 단 이론(plate theory)을 사용하였으며 모든 계산은 HCI 프로그램을 이용하여 계산하였다. 이동상의 조건은 일정용매조성법(isocratic mode)과 계단함수 구배용매조성법(step-gradient mode)을 이용하였다. 일정용매조성법에서 물과 메탄올의 조성비가 93/7 (v/v)일 때 최적 분석조건을 얻을 수 있었다. 분석시간의 단축을 위하여 계단함수 구배용매조성법을 사용하여 이동상의 조성을 물/메탄올 93/7 (v/v)에서 5 min 후에 75/25 (v/v)로 변경하는 최적조건을 계산했다. 위의 두 조건에서 실험을 수행하여 계산 용출 곡선과 실험값을 비교하였으며, 매우 잘 일치함을 보였다.

• 지역사회간호학회지
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• 제33권3호
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• pp.269-278
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• 2022

Purpose: This study analyzed the retention factors of Korean community health practitioners who sustained over 20 years based on a multi-dimensional framework. This study suggests global implications for nurses working in rural or remote areas, even during a worldwide pandemic. Methods: The participants were 16 Korean community health practitioners who worked in rural or remote locations for over 20 years. This study identified nurses' key retention factors contributing to long service in rural and remote areas. This is a qualitative study based on the narrative method and analysis was conducted using grounded theory. A semi-structured questionnaire was conducted based on the following: the life flow of the participants' first experience, episodes during the work experience, and reflections on the past 20 years. Results: First, personal 'financial needs' and 'callings' were motivation-related causal conditions. The adaptation of environment-work-community was the contextual condition leading to intervening conditions, building coping strategies by encountering a lifetime crisis. The consequences of 'transition' and 'maturation' naturally occurred with chronological changes. The unique factors were related to the 'external changes' in the Korean primary health system, which improved the participants' social status and welfare. Conclusion: Considering multi-dimensional retention factors was critical, including chronological (i.e., historical changes) and external factors (i.e., healthcare systems), to be supportive synchronously for rural nurses. Without this, the individuals working in the rural areas could be victimized by insecurity and self-commitment. Furthermore, considering the global pandemic, the retention of nurses is crucial to prevent the severity of isolation in rural and remote areas.