One of the major sources causing eutrophication and algal blooms of lakes or streams is phosphorus which comes from point and nonpoint pollution sources. HAP (hydroxyapatite) crystallization using granular alkaline materials can achieve the decrease of phosphorus load from wastewater treatment plants and nonpoint pollution control facilities. In order to induce HAP crystal formation, continuous supply of calcium and hydroxyl ions is required. In this research, considering HAP crystallization, several types of lime-based granular alkaline materials were prepared, and the elution characteristics of calcium and hydroxyl ions of each were analyzed. Also, column tests were performed to verify phosphorus removal efficiencies of granular alkaline materials. Material_1 (gypsum+cement mixed material) achieved the highest pH values in the column tests consistently, also, Material_2 (gypsum+slag mixed material) and Material_3 (calcined limestone material) achieved over pH 9.0 for 240 hours (10 days) and proved the efficiencies of long-term ion supplier for HAP crystallization. In the column tests using Material_3, considerable pH increase and phosphorus removal were carried out according to each linear velocity and filtration depth. T-P removal efficiencies were 87.0, 84.0, 68.0% and those of PO4-P 100.0, 97.0, 80.0% for linear velocity of 1.0, 2.5, 5.0 m/hr respectively. Based on the column test results, the applicability of phosphorus removal processes for small-scale wastewater treatment plants and nonpoint pollution control facilities was found out.
Data clustering is one of the most difficult and challenging problems and can be formally considered as a particular kind of NP-hard grouping problems. The K-means algorithm is one of the most popular and widely used clustering method because it is easy to implement and very efficient. However, it has high possibility to trap in local optimum and high variation of solutions with different initials for the large data set. Therefore, we need study efficient computational intelligence method to find the global optimal solution in data clustering problem within limited computational time. The objective of this paper is to propose a combined artificial bee colony (CABC) with K-means for initialization and finalization to find optimal solution that is effective on data clustering optimization problem. The artificial bee colony (ABC) is an algorithm motivated by the intelligent behavior exhibited by honeybees when searching for food. The performance of ABC is better than or similar to other population-based algorithms with the added advantage of employing fewer control parameters. Our proposed CABC method is able to provide near optimal solution within reasonable time to balance the converged and diversified searches. In this paper, the experiment and analysis of clustering problems demonstrate that CABC is a competitive approach comparing to previous partitioning approaches in satisfactory results with respect to solution quality. We validate the performance of CABC using Iris, Wine, Glass, Vowel, and Cloud UCI machine learning repository datasets comparing to previous studies by experiment and analysis. Our proposed KABCK (K-means+ABC+K-means) is better than ABCK (ABC+K-means), KABC (K-means+ABC), ABC, and K-means in our simulations.
본 연구는 장년층 1인가구를 대상으로 이들의 우울을 예측할 수 있는 요인을 분석하는 데 목적을 두었다. 이를 위해 한국복지패널 11차 자료(2016년)를 이용하여 50-64세 1인가구 268명을 대상으로 분석하였다. 로지스틱 회귀분석 결과, 성별, 주관적 건강상태, 취업 여부, 가족관계 만족도, 사회적 친분관계 만족도가 우울 가능성에 영향을 미치는 유의미한 변인으로 나타났다. 장년층 1인가구가 여성일 경우, 비취업자일 경우 우울 가능성이 높은 반면, 주관적 건강상태가 좋을수록, 가족관계 만족도가 높을수록, 사회적 친분관계 만족도가 높을수록 우울 가능성이 낮은 것으로 나타났다. 이러한 결과를 바탕으로 장년층 1인가구의 우울 예방과 감소를 위한 시사점을 제시하였다.
This study aimed to investigate growth rate and nutrient consumption of Chlorella vulgaris according to different light irradiation interval. Applied light irradiation intervals were 12 hr, 4 hr, 1 hr, and 1 min. The light source was flexible LED(Blue:Red=1:1), light intensity was 200 PPFD and Light/Dark cycle was 1:1. As a result, growth rate and nutrient removal efficiencies showed no significant differences depending on the light irradiation interval. Considering the reproduction characteristics of applied microalgae cultures of this study, this is thought to be one of the possible reasons of above results. Because Chlorella vulgaris performs an asexual reproduction and it is known that there is no significant relationship between light irradiation interval and growth rate, including nutrient consumption in case of asexual reproduction.
The aim of this study was to examine indoor fungal concentration and fungal volatile organic compounds(VOCs) in single-person households. A total of 22 houses occupied by one person were investigated in this study. 19 VOCs detected in the field were estimated as fungi-derived VOCs through a review of the literature, and 11 VOCs were confirmed as fungal VOCs by laboratory experiments. Exposure to fungal VOCs in the indoor environment has been confirmed to be highly influenced by airborne fungal concentration and indoor humidity. 3-octanone was characterized by a clear generation profile in Aspergilus versiocolor, and n-decane in Pencillum chrysogenum. ntetradecane emitted by Stachybotrys chartarum exhibited a tendency to occur consistently. The observations made in this study demonstrated that single-person households can easily be exposed to fungi, and MVOCs can be used as an indicator of fungal exposure in indoor environments.
The objective of this study was to quantify and characterize the inorganic nitrogen and phosphorus outflow loading from different water managements in paddy fields. We investigated the NO3-N, NH4-N, and PO4 in runoff from paddy fields in Iksan. The three different water management treatments were conventional continuous irrigation at 4 and 8 cm water levels, and intermittent irrigation at a 4 cm water level. The concentration of NO3-N at the early growth stage in surface water was 6.11 mg L-1, and then it gradually decreased. The downward curve increased slightly with additional nitrogen fertilization at the panicle initiation stage, and then it continued to decrease. The NH4-N concentration was 5.26 mg L-1, and that of PO4 was 0.70 mg L-1 at the early growth stage. However, the concentration of NO3-N peaked at 8.79 mg L-1 directly after transplantation and then decreased rapidly throughout the growing season. The amount of NH4-N runoff was 1.86 kg ha-1 in the plot with intermittent irrigation, and 2.0 kg ha-1 and 2.1 kg ha-1 in the plots with water depths of 4 and 8 cm, respectively. The NO3-N runoff was 7.43 kg ha-1 in the plot with intermittent irrigation, 8.62 kg ha-1 in the plot with a water depth of 4 cm, and 10.25 kg ha-1 in the plot with a water depth of 8 cm. In addition, the PO4 runoff was 0.42 kg ha-1 in the plot with intermittent irrigation, 0.48 and 0.55 kg ha-1 in the plots with water depths of 4 and 8 cm, respectively. The saving effect of irrigation water was 28.5% than that of conventional water management treatments, and the amount of nitrogen runoff was decreased by 18.5% with intermittent irrigation. However, the phosphorus runoff was not different between the different water management treatments in paddy fields.
Acetate, propionate, butyrate are the major soluble volatile fatty acids metabolites of fermented food waste leachates. This work investigate the effects of volatile fatty acid on the growth rate and NH4-N, PO4-P removal efficiency of mixotrophic microalgae Chlorella vulgaris to treat digested food waste leachates. The results showed that acetate, propionate and butyrate were efficiently utilized by Chlorella vulgaris and microalgae growth was higher than control condition. Similar trends were observed upon NH4-N and PO4-P consumption. Volatile fatty acids promoted Chlorella vulgaris growth, and nutrient removal efficiencies were highest when acetate was used, and butyrate and propionate showed second and third. From this work it could be said that using mixotrophic microalgae, in this work Chlorella vulgaris, fermented food waste leachates can be treated with high efficiencies.
Mill scale, an iron waste, was used to separate magnetite particles for the adsorption of phosphate from aqueous solution. Mill scale has a layered structure composed of wustite (FeO), magnetite (Fe3O4), and hematite (Fe2O3). Because magnetite shows the highest magnetic property among these iron oxides, it can be easily separated from the crushed mill scale particles. Several techniques were employed to characterize the separated particles. Mill scale-derived magnetite particles exhibited a strong uptake affinity to phosphate in a wide pH range of 3-7, with the maximum adsorptive removal of 100%, at the dosage of 1 g/L, pH 3-5. Langmuir isotherm model well described the equilibrium data, exhibiting maximum adsorption capacities for phosphate up to 4.95 and 8.79 mg/g at 298 and 308 K, respectively. From continuous operation of the packed-bed column reactor operated with different EBCT (empty bed contact time) and adsorbent particle size, the breakthrough of phosphate started after 8-22 days of operation. After regeneration of the column reactor with 0.1N NaOH solution, 95-98% of adsorbed phosphate could be detached from the column reactor.
본고는 1972년 미국 닉슨 대통령의 중국방문을 다룬 존 아담스(John Adams)의 오페라 《닉슨
인 차이나》(Nixon in China)를 미디어적 관점에서 분석한 연구이다. 《닉슨 인 차이나》는 동시
대 사건을 다룬 뉴스를 오페라 무대 위에서 재현했다는 점 때문에 세간의 주목을 끌었다. 그러나
미디어와의 이러한 표면적 연관성은 오히려 작품이 가진 보다 본질적이고 심층적인 미디어와의 연
관성에 대해서는 간과하도록 만들었다. 본 연구는 이러한 점에 착안하여 《닉슨 인 차이나》를 미
디어이론의 틀에서 접근한 새로운 해석을 시도하였다. 즉 본 작품의 내용과 형식에서 모두 미디어
적 속성이 반영되고 있으며 이를 통해 미디어가 현실에 영향력을 끼치는 모습을 작품 속에서 드러
내고 있음을 밝히고자 하였다.
미디어와의 다층적인 연관성이 《닉슨 인 차이나》의 리브레토, 음악, 연출에서 어떻게 나타나는
지 분석하여 현대사회 속 미디어의 모습을 반영하는 오페라로서의 본 작품을 고찰하였다. 분석의
내용은 다음과 같다.
첫째, 이 작품의 내용은 닉슨의 중국방문이 아니라, ‘미디어에 비친’ 닉슨의 중국방문이라는 점을
핵심으로 한다. 등장인물들은 TV를 시종일관 인식하고 있으며 이에 따라 대조적인 모습을 보여주어
현대인의 삶과 미디어의 연관성을 포착한다. 둘째, 내용을 담는 작품의 형식을 보면, 뉴스나 쇼 등
구체적인 텔레비전 프로그램의 모방이 나타날 뿐 아니라 패스티시와 플로우 등 텔레비전이 취하는
전형적 구성형식을 취하고 있음을 알 수 있다. 이러한 특성은 《닉슨 인 차이나》에서의 파편적 극
구성과 음악구성, 긴장과 이완의 호흡을 고려하여 시종일관 관객의 시선을 놓치지 않도록 하는 배열
등에서 나타난다. 셋째, 내용과 형식을 통해 드러나는 작품의 주제는 미디어적 현실에 대한 비판적
반성으로 볼 수 있다. 이에 사로잡힌 현대인의 모습을 《닉슨 인 차이나》에서는 정신분열증과 노
스탤지어를 통해서 포착한다. 통전적인 인식을 방해하는 미디어의 영향력은 분열된 자기의식, 기표
의 언어유희인 정신분열증을 통해 나타난다. 노스탤지어는 현실도피를 위한 상품화된 가상인데
《닉슨 인 차이나》에서는 노스탤지어 속에서도 이미 자리 잡고 있는 미디어의 모습을 통해 그 무
한 소급적 위력을 드러낸다. 미디어의 막강한 영향력은 하이퍼리얼리티의 생산에서 절정을 이룬다.
이는 현실보다 더 현실 같은 가상과 원본 없는 이미지의 유통을 의미하며 《닉슨 인 차이나》에서
는 극중극 장면에서 첨예하게 나타난다. ‘낯설게하기’는 이러한 주제를 구현하기 위한 효과적 극적
장치로 사용되어 미디어의 영향력에 대한 객관적 거리를 확보하게 한다.
이러한 분석을 근거로, 《닉슨 인 차이나》는 현대사회 속 미디어의 모습을 매개(mediate)하는
역할을 하는 오페라로서 독해가능하며 바로 이 점이 《닉슨 인 차이나》가 지닌 동시대적 오페라로
서의 진정한 지위와 가치를 보장해 주는 것이라고 할 수 있다.
온 인류를 향하신 하나님의 구속사적인 계획은 그 분의 시간표 안에서 이방 선교의 문이 열리기를 기다리며 준비되고 있었다. 박창현 이 지적한 것처럼 예수와 수로보니게 여인과의 만남 (마가복음 7:24-30)은 복음이 이방인들에게 열린 유대교적 종교개혁의 시작이 었다. 디아스포라의 유대 공동체는 이방인들과의 긴밀한 접촉을 통해서 새로운 변화에 개방적이며 자유로운 사고 방식을 가졌으며 국제 공용어 인 헬라어를 구사하였다. 한편 디아스포라 유대인들의 예배와 토라에 따른 생활양식을 접한 이방인들 가운데 이스라엘 민족의 역사와 삶 속에서 고백되어지는 하나님을 “경외하는 사람들”이 등장하게 되었다. 무엇보다도 히브리 성서의 헬라어 번역본(칠십인역)으로 인해 이방인 들에게도 성경을 읽을 수 있는 기회가 열리게 되었다. 이 논문에서는 초기 기독교 선교에 미친 디아스포라 유대인들의 헬라어 성서 번역본의 역할과 영향, 그리고 한국 교회 선교역사에서 활약한 한글 성경 번역의 의미를 살펴볼 것이다.
Daecheong Reservoir was made by the construction of a large dam (>15 m in height) on the middle to downstream of the Geum River and the discharge systems have the watergate-spillway (WS), a hydropower penstock (HPP), and two intake towers. The purpose of this study was to investigate the limnological anomalies of turbid water reduction, green algae phenomenon, and oligotrophic state in the lower part of reservoir dam site, and compared with hydro-meteorological factors. Field surveys were conducted in two stations of near dam and the outlet of HPP with one week intervals from January to December 2000. Rainfall was closely related to the fluctuations of inflow, outflow and water level. The rainfall pattern was depended on the storm of monsoon and typhoon, and the increase of discharge and turbidity responded more strongly to the intensity than the frequency. Water temperature and DO fluctuations within the reservoir water layer were influenced by meteorological and hydrological events, and these were mainly caused by water level fluctuation based on temperature stratification, density current and discharge types. The discharges of WS and HPP induced to the flow of water bodies and the outflows of turbid water and nutrients such as nitrogen and phosphorus, respectively. Especially, when hypoxic or low-oxygen condition was present in the bottom water, the discharge through HPP has contributed significantly to the outflow of phosphorus released from the sediment into the downstream of dam. In addition, HPP effluent which be continuously operated throughout the year, was the main factor that could change to a low trophic level in the downreservoir (lacustrine zone). And water-bloom (green-tide) occurring in the lower part of reservoir was the result that the water body of upreservoir being transported and diffused toward the downreseroir, when discharging through the WS. Finally, the hydropower effluent was included the importance and dynamics that could have a temporal and spatial impacts on the physical, chemical and biological factors of the reservoir ecosystem.
This study was carried out to investigate the characterization of iron oxide nanotubes (INTs) by anodization method and applied adsorption isotherms and kinetic models for phosphate adsorption. SEM analysis was conducted to examine the INTs surface formation. Further XRD and XPS analysis were performed to observe the crystal structure of INTs before and after phosphate adsorption. AFM analysis was conducted to determine of Fe foil surface before and after anodization. Phosphate stock solution for adsorption experiment was prepared by KH2PO4. The batch experiment was conducted using 20 ml phosphate stock solution and 40 cm3 of INTs in 50 ml conical tube. Adsorption isotherms were applied Langmuir and Freundlich models for adsorption equilibrium test of INTs. Pseudo first order and pseudo second order models were applied for interpretation of adsorption rate by reaction time. The determination coefficient (R2) values of Langmuir and Freundlich models were 0.9157 and 0.8876 respectively.
Modified coagulants were investigated for the removal of phosphorus from secondary effluent of wastewater treatment. The modified coagulants were prepared by mixing alkali earth metal ions such as calcium and magnesium. The basicity of a coagulant influenced on the removal of phosphorus, and coagulants with basicity of 5.9% showed a better removal of total phosphorus than that of 38.5%. Also, coagulants with alkali earth metals enhanced the performance of coagulation by 10% and resulted in 67.1% for total phosphorus removal. Moreover, the removal of suspended solids and chemical oxygen demand was improved using coagulants with low basicity and earth metal ions. Results of this study demonstrated that the use of coagulants with low basicity, and calcium and magnesium ions is recommended to improve wastewater effluent quality.
Coagulation/precipitation process has been widely used for the removal of phosphate within domestic wastewater. Although Fe and Al are typical coagulants used for phosphate removal, these have some shortages such as color problem and low sedimentation velocity. In this study, both Fe and Al were used to overcome the shortages caused by using single one, and anionic polymer coagulant was additionally used to enhance sedimentation velocity of the precipitate formed. Batch experiments using a jar test were conducted with real wastewater, which was an effluent of the second sedimentation tank in domestic wastewater treatment plant. Response Surface Methodology was used to examine the responsibility of each parameter on phosphate removal as well as to optimize the dosage of the three coagulants. Economic analysis was also done on the basis of selling prices of the coagulants in the field. Phosphate removal efficiency of Fe(III) was 30% higher than those of Fe(II). Considering chemical price, optimum dosage for achieving residual phosphate concentration below 0.2 mg/L were determined to be 18.14 mg/L of Fe(III), 2.60 mg/L of Al, and 1.64 mg/L of polymer coagulant.