• 상하수도학회지
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• 제22권5호
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• pp.551-559
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• 2008

An experimental study was carried out to evaluate the potential of flotation process for the secondary clarifier of an activated sludge process. Flotation techniques, applied in this study, include electrofloation (EF) which generated fine bubbles smaller than $35{\mu}m$ in average and diffuser flotation (DF) which generated fine bubbles smaller than $55{\mu}m$ in average. The batch experiments were done with activated sludge displaying various characteristics. It was shown that the efficiency of solids/liquid separation was reduced as the diluted sludge volume index ($DSVI_{30}$) of activated sludge increased. The dependency, however, gradually decreased as the gas to solids (G/S) ratio increased. Thickening efficiency of EF was more than 2~10 times and DF process was more than 1.5~5 times as compared with gravity sedimentation (GS). Stable sludge blanket was maintained regardless of sludge settleability when the G/S ratio was 0.019 in the EF. On the other hand, Serious deterioration in the sludge blanket was observed in the DF depends on G/S ratio and sludge settleability. And For EF and DF, the suspended solids concentration of effluent was not nearly influenced on settleability of activated sludge and more clear than GS. A biological nutrient removal (BNR) process, combined with EF as a secondary clarifier was operated for three months. The mean MLSS (mixed liquid suspended solids) concentration in the reactor and mean solids concentration of return sludge were estimated to be 5,340 mg/L and 16,770 mg/L, respectively. The water quality of effluent was considerably stable and low value was accomplished, that was, standard suspended solids concentration $0.07{\pm}0.51mg/L$ and standard turbidity $1.44{\pm}0.56NTU$. The EF could be applicable for enhancement of efficiency of activated sludge system as well as improvement of the water quality of effluent.

• 한국해양공학회지
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• 제22권5호
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• pp.7-24
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• 2008

Masan-Jinhae Bay, in Korea, is known for its frequent algal bloom outbreaks. This study was conducted in order to examine the environmental characteristics of the area, with the aim of identifying indicators that could be used to speculate about future algal blooms. The water temperatures and salinities in Haengam Bay, one of the small inner bays within Jinhae, appeared to re relatively higher than those in Masan and Jinhae bays, across most seasons. Furthermore, stratification begins to develop in all three regions from spring to summer as a result of the local heating effects and an increase in the efficient from the surrounding land. As a result, anoxic conditions appear near the bottom layer of the bay, leading to the deterioration of water quality, which has been identified as one of the causes of bloom outbreaks. Compared to Haengam and Jinhae bays, concentrations of DIN and DIP were remarkably higher in Masan Bay. However, the mean ratio of DIN to DIP was 3.3$\sim$13.6 in all three regions throughout the year, suggesting that nitrogen can function as a growth-limiting factor for phytoplankton. The results of mathematical models showed that cumulative organic pollutants may be a trigger for direct algal bloom occurrences, since residual tidal currents appeared to be less than $3\;cm\;\cdot\;s^{-1}$. Furthermore, computed DO concentrations in the four small inner bays of Jinhae during the summer appeared to be $3\;cm\;\cdot\;l^{-1}$ indicating a hypoxic state. Likewise, computed Chl-a concentrations turned out to be more than $0.01\;mg\;\cdot\;l^{-1}$, indicating eutrophication across most seasons. Based on the overall results, Masan-Jinhae Bay appeared to possess a very high potential for algal bloom outbreaks at anytime during the year.

• 한국환경보건학회지
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• 제44권2호
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• pp.115-123
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• 2018

Objectives: Preservatives, suspected to be endocrine disrupting chemicals, are widely used in feminine hygiene products for the prevention of deterioration. Information regarding the usage patterns of feminine hygiene products and the concentrations of preservatives in these products is limited. The present study was conducted to investigate the use of feminine cleansers among Korean women and quantify the concentration of preservatives in feminine cleansers. Methods: Approximately 500 women were recruited from the city of Busan in August 2017 and a questionnaire survey was conducted on the use of feminine cleansers. Several major feminine hygiene products (n=69) were identified and selected for analysis of 22 preservatives. Following appropriate preparation, the products were analyzed by HPLC/DAD. Results: Over 70% of the participating women used at least one feminine cleanser. Marital status and parity were associated with the frequency of use. Liquid was most frequently used form of feminine cleanser (66.6%). The greatest proportion of subjects answered that they use it 'one to two times per week' (36.5%). Among the 69 feminine cleansers, benzoic acid, sorbic acid, phenoxyethanol, and methyl paraben were detected at $144-4,428{\mu}g/g$, $195-1,470{\mu}g/g$, $269-4,237{\mu}g/g$, and $625-4,901{\mu}g/g$, respectively. BA was the most frequently detected (46.4%). Conclusions: In the present study, the characteristics of feminine cleanser use among Korean women were investigated. Based on an analysis of preservatives in the feminine hygiene products, one product was determined to exceed the maximum authorized concentration of MeP (0.4%). Our results will help refine exposure and risk assessment for toxic chemicals in feminine cleansers.

• 대한토목학회논문집
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• 제8권1호
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• pp.61-68
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• 1988

본(本) 연구(硏究)에서는 군용전차의 교량통과시 노후도(老朽度)를 비롯한 각종 저항(抵抗) 및 하중(荷重)관련 불확실량(不確實量)을 체계적으로 포함한 한계상태모형(限界狀態模型)을 유도하고, 실용적이며 진보된 2차(次)모멘트 신뢰성(信賴性) 이론(理論)을 사용하여 군용교량(軍用橋梁) 및 일반교량(一般橋梁)의 신뢰성(信賴性)에 기초한 안전도(安全度) 분석방법(分析方法)과 하중저항계수(荷重抵抗係數) 형식의 급수계산방법(級數計算方法)을 제안(提案)하였다. 본(本) 연구(硏究)에서 제안(提案)하는 안전도(安全度) 분석(分析) 및 내하급수(耐荷級數) 판정방법(判定方法)을 몇 개의 실제 교량에 적용하여 보았다. 본(本) 연구(硏究)의 결과 현행 재래식 허용응력개념에 의한 NATO 급수계산방법은 실내하력(實耐荷力) 판정(判定)이 아닌 명목적인 급수판정방법에 불과함을 알 수 있으며, 따라서 본 연구에서 제시(提示)한 신뢰성방법(信賴性方法)에 의한 안전도(安全度) 분석방법(分析方法)과 하중(荷重)-저항계수(抵抗係數)형 급수 계산방법이나 이에 대응하는 합리적인 허용응력법(許容應力法)에 의한 실내하급수(實耐荷級數) 계산방법(計算方法)의 도입이 시급하다고 본다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권3호
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• pp.12-22
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• 2020

Managed aquifer recharge (MAR) is a promising water management strategy for securing stable water resources to overcome water shortage and water quality deterioration caused by global environmental changes. A MAR demonstration site was selected at Imgok-ri, Sangju-si, Korea, based on screening for the frequency of drought events and local water supply situations. The abundant groundwater discharging from a nearby abandoned coal mine is one of the potential recharge water sources for the MAR implementation. However, it has elevated levels of arsenic (~12 ㎍/L). In this study, the potential of the natural attenuation of arsenic by the field geological media was investigated using batch and column experiments. The adsorption and desorption parameters were obtained for two drill core samples (GM1; 21.8~22.8 m and GM2; 26.0~27.8 m depth) recovered from the potentially water-conducting fracture-zones in the injection well. The effluent arsenic concentrations were monitored during the continuous flow of the mine drainage water through the columns packed with the core samples. GM2 removed about 60% of arsenic in the influent (0.1 mg-As/L) while GM1 removed about 20%. The results suggest that natural attenuation is an acitive process occurring during the MAR operation, potentially lowering the arsenic level in the mine drainage water below the regulatory standard for drinking water. This study hence demonstrates that using the mine drainage water as the recharge water source is a viable option at the MAR demonstration site.

• 한국의학물리학회지:의학물리
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• 제21권1호
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• pp.42-51
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• 2010

뇌 기능 연구 분야에서는 MRI, PET, MEG 영상 시스템 등을 이용한 인지기능에 대한 정량적 평가 연구가 계속적으로 이루어 지고 있다. 최근에는 컴퓨터 기술을 응용하여 인지 기능의 정량적 분석을 효과적으로 하고자 시도되고 있다. 본 연구에서는 터치 스크린을 이용하여 인지 기능의 정량적 평가를 할 수 있는 소프트웨어 패키지를 구현하였다. 여기서 구현된 내용은 집중력, 숫자 기억력, 조합 기억력, 위상 기억력, 시각 및 근육 반응, 청각 반응 등으로 되어 있다. 우리는 구현된 소프트웨어에 대하여 실험적 검증과정을 거치고자 20~59세까지의 연령 및 성별에 따른 80명을 대상으로 실험을 수행하였다. 남녀 모두 40세 이후의 연령에서 인지기능의 감쇄가 일어나는 결과를 정량적 획득하였다. 본 연구에서는 고가 장비인 영상 시스템뿐만 아니라 상대적으로 간소화된 소프트웨어를 이용하여서도 인지기능의 정량적 평가가 가능함을 보여주고 있다. 이러한 방법을 적용하여 다양한 그룹의 인지 기능의 정량적 평가 및 비교를 수행하는 데 비용과 시간을 줄일 수 있을 것으로 보인다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권4호
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• pp.1-9
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• 2016

Rehabilitation for low-yielding wells resulting in improvement on groundwater quantity and quality is considered to be the most economic and ecofriendly method against the increasing demand to groundwater due to frequent drought and the increase in numbers of agricultural complex for growing horticultural crops. This study suggests standard, stepwise diagnostic fuctions consisting of four steps (Basic inspection, Specific inspection, Rehabilitation, and Management) for an optimal management to the wells. Basic inspection can provide information on current groundwater quantity and quality compared with those on its initial stage. Specific-inspection based on hydrogeology can scientifically demonstrate causes of deterioration on groundwater quantity and quality. Results of specific inspection can suggest an optimal rehabilitation method to solve deteriorating problems including clogging and corrosion for the wells. After rehabiliating the wells, an assessment on groundwater quantity and quality would be conducted to identify the suitability of the applied method and improvement of the wells. A short-term, periodic management to the wells is considered as the key to save a public management budget. Suggested diagnostic functions can possibly induce sustainable supply of agricultural groundwater to the farm land and finally contribute the increase on rural household income.

• 대한두경부종양학회지
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• 제16권2호
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• pp.191-195
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• 2000

Objectives: Despite various attempts to preserve the normal voice in advanced laryngeal cancer, it is inevitable for many advanced laryngeal cancer patients to undergo total laryngectomy and thus making a trade off between quality and quantity of life. Laryngectomees are faced with voice loss, change in physical appearance and health deterioration which hinder their efforts to rehabilitate back into their family and employment leading to poor quality of life. The objectives of this study were to evaluate the quality of life in long term surviving laryngectomees to, define the factors which are most important in determining their present quality of life and to propose a theoretical model for quality of life after laryngectomy in Korea. Materials and Methods: From 1986 to 1995, 120 laryngectomees with no evidence of disease were followed up for at least 3years were evaluated. Each of 15 quality of life domains with a total of ten points were given for a quality of life score. Results: There was no significant difference in the physical-mental adaptation index such as general health and mental health between the laryngectomees and control group(p>0.05). However, social adaptation index such as social activity, occupational status and economic status for laryngectomees were significantly lower with 2.3, 3.5, and 4.4 points compared to control group with 8.5, 7.6, and 7.1 points respectively(p<0.05). Conclusion : Vocational and social rehabilitation should be emphasized with highest priority for improving their economic status and thus improving their quality of life.

• 한국항공우주학회지
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• 제32권4호
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• pp.43-52
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• 2004

본 논문에서는 아리랑 1호의 실제 비행데이터를 이용하여 지상에서 정밀궤도결정을 수행한 후 얻을 수 있는 성능에 대해 분석하였다. 분석에 사용된 궤도결정 알고리즘은 바예 시안 최소자승법을 작용한 배치필터이며, 궤도결정 정밀도 평가를 위해 중첩법 (Overlap Method) 을 이용하였다. 또한, 미국 NORAD 의 TLE (Two-Line Element) 및 지상추적 데이터를 이용한 궤도결정 결과들과의 비교, 분석도 수행하였다. 궤도결정 정밀도에 영향을 미칠 수 있는 요인, 즉 관측데이터 종류 및 탑재시계 편류 (On-Board Time Drift)에 의한 정밀도 변화에 대해서도 분석되어졌다. 본 연구결과, 중첩법 평가에 의한 30시간 GPS 항행해 위치 성분만을 이용한 궤도결정 정밀도는 5m RMS 수준이었으며, GPS 항행해 중 속도 성분은 궤도결정 시 사용하지 않는 것이 바람직하며, 타 관측데이터를 이용한 궤도결정 결과와의 비교를 통해 심각한 시각 바이어스에 의한 뚜렷한 정밀도 저하는 없음을 알 수 있었다.

• Journal of Korean Neurosurgical Society
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• 제42권4호
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• pp.331-336
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• 2007

Objective : The aim of this study was to analyze the treatment results and prognostic factors in patients with massive cerebral infarction who underwent decompressive craniectomy. Methods : From January 2000 to December 2005, we performed decompressive craniectomy in 24 patients with massive cerebral infarction. We retrospectively reviewed the medical records, radiological findings, initial clinical assessment using the Glasgow Coma Scale, serial computerized tomography (CT) with measurement of midline and septum pellucidum shift, and cerebral infarction territories. Patients were evaluated based on the following factors : the pre- and post-operative midline shifting on CT scan, infarction area or its dominancy, consciousness level, pupillary light reflex and Glasgow Outcome Scale. Results : All 24 patients (11 men, 13 women; mean age, 63 years; right middle cerebral artery (MCA) territory, 17 patients; left MCA territory, 7 patients) were treated with large decompressive craniectomy and duroplasty. The average time interval between the onset of symptoms and surgical decompression was 2.5 days. The mean Glasgow Coma Scale was 12.4 on admission and 8.3 preoperatively. Of the 24 surgically treated patients, the good outcome group (Group 2 : GOS 4-5) comprised 9 cases and the poor outcome group (Group1 : GOS 1-3) comprised 15 cases. Conclusion : We consider decompressive craniectomy for large hemispheric infarction as a life-saving procedure. Good preoperative GCS, late clinical deterioration, small size of the infarction area, absence of anisocoria, and preoperative midline shift less than 11mm were considered to be positive predictors of good outcome. Careful patient selection based on the above-mentioned factors and early operation may improve the functional outcome of surgical management for large hemispheric infarction.