• Korea-Australia Rheology Journal
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• 제21권4호
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• pp.289-297
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• 2009

We numerically analyzed flow characteristics of the polymer melt in the screw equipment using a proper modeling and investigated design parameters which have influence on the mixing performance as the capability of the screw equipment. We considered the non-Newtonian and non-isothermal flow in a single rotor equipment to investigate the mixing performance with respect to screw dimensions as shape parameter of the single rotor equipment and screw speed as process parameter. We used Bird-Carreau-Yasuda model as a viscous model of the polymer melt and the particle tracking method to investigate the mixing performance in the screw equipment and considered four mixing performance indexes: residence time distribution, deformation rate, total strain and particle standard deviation as a new mixing performance index. We compared these indexes to determine design parameters and object function. On basis of the analysis results, we carried out the optimal design by using the response surface method and design of experiments. In conclusion, the differences of results between the optimal value and numerical analysis are about 5.0%.

• 한국안전학회지
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• 제8권2호
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• pp.44-50
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• 1993

The objective of this study was to investigate the extraction of chromium(Vl) ion in waste water through the liquid surfactant membrane with open-type Perforated Reciprocating-Plate Column. Extraction experiments were conducted to measure the effect of flow characteristics of continuous and dispersed phase and stroke velocity, sodium hydroxide concentraction in internal aqueous phase, sulfuric acid concentraction in outer phase, and residence time distribution and measured extraction velocity. The result of experiments showed that extraction velocity of chromium ion was maximum when stroke velocity was 180 1/min and dispersion phase velocity was 30m11min, continuous phase velocity was 20m1/min. Extraction velocity of chromium ion increased with increasing difference of hydrogen ion concentraction of dispersion and continuous phase and column stage decreased.

• 성인간호학회지
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• 제15권1호
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• pp.105-115
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• 2003

Purpose: The research purposes analyzed the study participation and lecture evaluation of applicants in the cyber hospice specialist education course to find problems of nurse education application on the web. Method: Study participants were 125 nurses for participation and 68nurses for lecture evaluation. The data was analysed by descriptive statistics. Result: The results obtained from this study were as follows 1) The residence distribution of study participants was spread out across the nation. Equal distribution of education was accomplished without a difference among provinces. 2) The average study duration in the study participation was about one hour and a quarter minutes a week, and number of access to lecture notes was 65.8 times. But in a discussion room and a cooperative room, the system using rate was very low, so we considered the idea to come up with a more effective application way. 3) The participant's lecture evaluation of cyber education were generally satisfied about the quality of lecture, time, contents etc. Conclusion: This study shows the possible implication for nursing fields using a web-based learning program for reeducation in a variety of fields, so nursing cyber application can be considered to come up with this more effective method.

• 한국환경농학회지
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• 제41권3호
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• pp.177-184
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• 2022

BACKGROUND: Recently, the inflow of nonpoint pollutants into rivers caused by rapid urban and industrialization promotes the proliferation of algae, which causes eutrophication of rivers. This study was conducted to evaluate the seasonal variation of water quality characteristics and cryptomonads growth in the Oncheon River. METHODS AND RESULTS: The water quality and distribution characteristics of cryptomonads in the Oncheon River were investigated monthly for 12 months from January 2021. The cell number of cryptomonads was intensively developed in January-April, and it decreased sharply in the summer with heavy rainfall. In particular, cryptomonads moved to the downstream side of the river depending on the time, and as a result, significant differences were shown for each investigation point. The Korean trophic state index (Tsi_KO) in Oncheon River was classified as eutrophy all year round, indicating that cryptomonads can grow year-round. Distribution characteristics of cryptomonads in Oncheon River showed high correlations with DO (r=0.678), BOD (r=0.826) and chlorophyll-a (r=0.613) in water. CONCLUSION(S): In order to reduce cryptomonads in the Oncheon River, it is judged that a complex countermeasure considering the residence time, insolation and precipitation along with water quality factors is required.

• 대한환경공학회지
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• 제27권2호
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• pp.177-183
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• 2005

하 폐수 처리장의 방류수 수질은 최종 침전지의 성능에 의해 직접적으로 영향을 받으므로 최종 침전지의 효율적 설계 및 운전은 하 폐수 처리에 소요되는 비용 절감과 더불어 수질보전을 위한 하수 정화의 목표를 달성할 수 있다. 그러므로 본 연구에서는 장방형 최종 침전지의 성능 개선을 위하여 유입구 위치와 정류벽 설치에 따른 내부 유동특성 및 고형물질의 제거효율을 수치해석방법을 통해 평가하였다. 개발된 2차원 컴퓨터 프로그램은 방사성 추적자를 이용한 체재시간분포 곡선과의 비교를 통해 성공적으로 검증된 수치해석 모델로 수력학적 구조변경에 대한 침전지의 성능 예측을 가능하게 하였다. 최종 침전지의 유입구 위치는 낮을수록 침전지에 형성된 강력한 바닥흐름과 수표면 역흐름으로 나타나는 밀도류를 저감시켰으며 침강된 슬러지의 하류 이동을 감소시켰다. 최종 침전지 유입부에 설치된 정류벽은 유입수가 출구로 직접 흐르는 단락류를 방지하고 밀도 저류로 유입되도록 하여 방류수 수질을 향상시키나 유입구 위치가 낮은 경우에 설치된 정류벽은 오히려 방류수 수질을 떨어뜨리는 결과를 초래하였다. 결국 최종 침전지의 성능 개선을 위한 수력학적 구조변경 및 설계는 다양한 변수에 대한 조직적인 수치해석 연구가 필요하며 선행되어야 할 것으로 판단된다.

• 한국수자원학회논문집
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• 제57권4호
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• pp.263-276
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• 2024

지형구조가 복잡한 자연하천에서의 오염물질의 혼합과 이송 현상을 해석하기 위해 개발된 1차원 저장대 모형은 1970년대에 처음으로 제시된 이후 하천 내 오염물질의 정체 현상의 정확한 분석을 목적으로 다양한 형태로 개선되어 왔으며, 지난 수년간 지표수 및 지하수 분야에서 오염물질의 거동 및 체류시간을 예측하는 도구로써 활발히 활용되어 왔다. 그럼에도 불구하고 1차원 저장대 모형은 복잡한 자연하천의 혼합 기작을 제한된 매개변수를 통해 단순화하기 때문에 아직 해결되지 않은 숙제가 남아 있다. 본 리뷰 논문에서는 현재까지 개발된 저장대 모형의 장·단점을 설명하고, 모형의 구조적, 비구조적 불확실성에 대한 문제를 제기하고, 이를 극복하기 위해 필요한 연구의 방향성을 제시하였다. 본 연구 결과, 지속적인 정체시간분포 모델링에 대한 개선, 동수역학 해석 모형과 저장대 모형과의 결합, 그리고 추적자 실험 자료 수집 과정에서 불확도 개선을 통해 저장대 모형의 정확도를 향상시킬 수 있음을 알 수 있다. 모형의 복잡성을 증가시켜 정확도를 강화하는 방안은 지양하여야 하며, 모형 매개변수를 통한 하천의 정체특성 해석에는 수리·지형학적 근거와 추적자 실험 자료와 매개변수 추정 방식의 신뢰성이 함께 제시되어야 한다. 본 연구의 분석 결과와 제언은 저장대 모형을 통한 정밀한 하천 혼합 해석의 향후 연구에 토대가 될 것으로 기대한다.

• 국토계획
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• 제54권3호
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• pp.75-90
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• 2019

As the 24-hour society arrives, human activities in daytime and nighttime urban spaces are changing drastically, and the need for new urban management policies is steadily increasing. This study analyzes the types and characteristics of Seoul's human dynamics using location-based big data and the results are summarized as follows. First, the pattern of human dynamics in Seoul repeats itself every 7 days. Second, the types of human dynamics in Seoul can be classified into five types, and each of type has its own unique time-series and local characteristics. Third, the degree of match between human dynamics and zoning system in urban planning legislation was highest in 'Type 1' residence pattern and low in other types. The following implications can be drawn from these results. First, This paper examined the methodology of analyzing the regional characteristics of Seoul through the human dynamics and obtained meaningful results. Second, This paper can derive reliable and objective pattern analysis results using Big data that reflect the overall population characteristics. Third, the scale of night-time activity in the urban space of Seoul was understood, and its distribution, patterns and characteristics identified.

• 한국보건간호학회지
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• 제9권2호
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• pp.80-91
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• 1995

This Study was conducted to describe relatioship between health promoting behaviors and Self-efficacy of 427 Students during the period form June 1. 1994 to June 30. 1994. The research Scale used Kim and Choe's (994) that was modified Sheredr and Maddux's (1982) Self-efficacy measurement scale. Data was. analysed by SPSS-PC program. and reavealed to percentage. t-value. F-value and Pearson's correlation coefficency. 1. The general characteristics of subjects was that men $55\%$. average age 22.5years old. There are the most highest destribution in religion. abscence $52.2\%$. and in residence. own house $49.9\%$ There are 129 subjects $(30.2\%)$ regularity exerciseed now. and 46 subjects $(35.7\%)$ exercise time was above 30 mins below 1 hour. There are 78 subjects $(60.5\%)$ above 4 times per weeks the most highest distribution in exercise times. 2. Health promoting behaviors score of subjects was 94.287 (2.548) and self-efficacy was 967.63 (69.12) 3. There are statistically significant difference in health promoting behavior score according to sex. sibling number. residence place (p<.05). In the subconcept of health promotion lifestyle profile (HPLP). there was the more higher score in men than women for self actualization (t=2. 67. p=.008). exercise(t=5.92. p=.000). There are statistically significant difference in nutrition according to sibling number (F=3.05. p=0.01). resident place (F=2.93. p=0.02). and in interpersonal support according to religion (F=2.88. p=0.02). 4. In the Self-efficacy score. there was statistically significant difference according to sex (t= 5.88. p=.000). 5. There was postive correlation between health promoting behavior and self-efficacy (r=.43. p=.000). On the basis of this result. I hope that develp Korean type health promoting behavior scale to understand health promotion for people. and nursing intervention method to improve health promoting behavior through increasment of Self-efficacy.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년 춘계학술발표대회 논문집
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• pp.243-246
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• 2009

Housing distribution rate in our country has been continuously increased with economic growth, but residential plans satisfying the demands of residents are still not perfect yet. The demands of residents can be predicted by analyzing the housing viewpoint of residents. And also, the housing viewpoint can change according to various environmental changes, so it's important for us to understand the trend of change. Therefore, the housing viewpoints of university students who will be subjective residents of houses in future were analyzed by observing change due to trend of time. Target for this study is female university students in 20s. A portion of previously presented material (Korean Home Economics Association 37,1, 67-78) was used as data for 1998 and a questionnaire with 171 female university students was conducted on December 2008 for data for 2008. The following result was drawn from examination of change in the housing viewpoint due to trend of time by comparing the housing viewpoint of university students between 1998 and 2008. First, importance of was decreased and importance of was increased in functions of residence. Second, Most students thought and regardless of the time passage as their opinions on housing. And also, most students considered a living room as the most important space inside of a house regardless of the time passage and the ratio of considering a living room as the most important space was more increased.

• The Korean Journal of Ecology
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• 제28권4호
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• pp.181-188
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• 2005

Methods used to study carbon sequestration by soil aggregates have often excluded the concentric spatial variability and other dynamic processes that contribute to resource accessibility and solute transport within aggregates. We investigated the spatial gradients of carbon (C) and nitrogen (N) from the exterior to interior layers within macroaggregates, $6.3\sim9.5$ mm, sampled from conventional tillage (CT) and no tillage (NT) sites of a Hoytville silt clay loam. Spatial gradients in C accumulation within macroaggregates were related to the differences in C dynamics by determining the sizes and the turnover rates of fast C and slow C pools in the concentric layers of aggregates. Aggregate exteriors contained more labile C and were characterized by greater C mineralization rates than their interiors in both management systems. In contrast, C in the interior layers of aggregates was more resistant in both systems. These results indicated the spatial differentiation of C dynamics within macroaggregates, i.e., exterior layers as a reactive site and interior layers as a protective site. Greater total C distribution in the exterior layers of NT aggregates indicated more influx of C from the macropores in interaggregate space than C. mineralization (net gain of C), whereas lower C distribution within the exterior layers of CT aggregates indicated net loss of C by greater C mineralization than C influx. We found total C increased approximately 1.6-fold by the conversion of CT soils to NT management systems for a period of 36 years. Differences in total accumulation and the spatial distribution of C within aggregates affected by management were attributed to the differences in aggregate stability and pore networks controlling the spatial heterogeneities of resource availability and microbial activity within aggregates.