• 상하수도학회지
• /
• 제31권6호
• /
• pp.539-549
• /
• 2017

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of $2.13kgf/cm^2$, but it was recovered to the initial level ($0.17kgf/cm^2$) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.

• 한국농공학회지
• /
• 제35권1호
• /
• pp.50-58
• /
• 1993

The sedimentation patterns at a reservoir, important to the reservoir capacity curve were simulated using a depth averaged, two-dimensional sediment transport model, that is capable of depicting velocity distributions and sediment transportation. The Banweol reservoir, whose stage capacity relationships have been surveyed before and after the construction, was selected and the daily inflow rates and stages were simulated using a reservoir operation model(DI-ROM). The applicability of the transport model was tested from the comparisons of simulated sedimentation patterns to the surveyed results. The simulated inflow rates and water level fluctuations at the reservoir during twenty-one years from 1966 to 1986, showed that water levels exceeding 80 percent of the total capacity occurred for 70 percent of the periods and inflow rates less than 5000rn$^3$/day sustained for 54 percent of the spans. Dorminant flow directions were simulated from two streamflow inlets to the dam site. And simulated sediment concentrations were higher near the inlets and lower at the inside of the reservoir. Sediment was deposited heavily near the inlets, and portions of sediments were distributed along the flow paths within the reservoir. The comparisons between the simulation results and the surveyed depositions were partially matched. However, it was not possible to compare two results at the upper parts of the reservoir where dredging was carried out few times for the purpose of reservoir maintenance. This study demonstrates that sedimentation patterns within the reservoir are closely related to incoming sediment and flow rates, water level fluctuations, and flow circulation within the reservoir.

• 한국의류산업학회지
• /
• 제23권4호
• /
• pp.515-526
• /
• 2021

This study aimed to investigate the evaluation of firefighting gloves and the behavior regarding their usage, of firefighting officials in Seoul, using a questionnaire. Responses from a total of 270 firefighters who are responsible for putting out fires or undertaking rescue works in Seoul were analyzed. As per the findings, the firefighters considered ease of hand operation and fire/flame protection as the most important performance factors for firefighting gloves, and they were satisfied with the supply status of the gloves. The average number of firefighting gloves currently owned by the firefighters was 2.6 ± 0.8 pairs. Thirty-nine percent of the respondents said that their firefighting gloves lasted, with maintained performance, for more than six months and less than a year, and when asked how they handled the gloves with degraded performance, 46% of them said that they would discard them. Sixty-eight percent of the respondents said that they used the most recently developed and supplied gloves, which they considered as the most satisfying gloves and which they mainly used these days. Respondents were highly satisfied with the fire/flame protection performance of their firefighting gloves, but were less satisfied, however, with the glove fit. These results suggest that there has been a significant improvement in the overall performance level and supply status of the firefighting gloves. Given the current situation, careful considerations with flexible approaches are needed on the current firefighting gloves size system as well as on the personal protective equipment maintenance and management scheme.

• 한국해양공학회지
• /
• 제35권5호
• /
• pp.382-392
• /
• 2021

In recent years, floating offshore wind turbines have attracted more attention as a new renewable energy resource while bottom-fixed offshore wind turbines reach their limit of water depth. Various projects have been proposed with the rapid increase in installed floating wind power capacity, but the economic aspect remains as a biggest issue. To figure out sensible approaches for saving costs, a comparison analysis of the levelized cost of electricity (LCOE) between floating and bottom-fixed offshore wind turbines was carried out. The LCOE was reviewed from a social perspective and a cost breakdown and a literature review analysis were used to itemize the costs into its various components in each level of power plant and system integration. The results show that the highest proportion in capital expenditure of a floating offshore wind turbine results in the substructure part, which is the main difference from a bottom-fixed wind turbine. A floating offshore wind turbine was found to have several advantages over a bottom-fixed wind turbine. Although a similarity in operation and maintenance cost structure is revealed, a floating wind turbine still has the benefit of being able to be maintained at a seaport. After emphasizing the cost-reduction advantages of a floating wind turbine, its LCOE outlook is provided to give a brief overview in the following years. Finally, some estimated cost drivers, such as economics of scale, wind turbine rating, a floater with mooring system, and grid connection cost, are outlined as proposals for floating wind LCOE reduction.

• Archives of Plastic Surgery
• /
• 제50권4호
• /
• pp.415-421
• /
• 2023

The revision of the Korea Organ Transplantation Act (KOTA) in 2018 included hand/arm among the organs that can be transplanted. The first hand transplantation since the revision of KOTA took place in January 2021. A 62-year-old male patient experienced hand amputation on July 13, 2018, by a catapult injury. The patient first visited our institute 3 months after the injury. After serial interviews and an overall evaluation, the patient was registered on the hand transplantation waiting list in January 2020. On January 9, 2021, the patient underwent hand transplantation at the right distal forearm level. The total operation time was 17 hours 15 minutes, and the cold ischemic time was 4 hours 9 minutes. Postoperative immunosuppression was administered based on the protocol used for kidney transplantation. Two acute rejection episodes occurred, on postoperative days 33 and 41. Both rejection episodes were reversible with rescue therapy of a higher tacrolimus trough level, steroid pulse therapy, and topical immunosuppressants. Controlled passive range of motion exercise was started on postoperative day 10. Dynamic splint was applied on postoperative day 18. At 1 year, graft maintenance and functional improvement were satisfactory, and the patient showed a Disabilities of Arm, Shoulder and Hand score of 25.8. We successfully performed the first hand transplantation surgery under the KOTA amendment. It came from the organic and effective cooperation of plastic, orthopaedic, and transplantation departments and we believe it will guarantee the future ongoing success.

• 한국산학기술학회논문지
• /
• 제16권5호
• /
• pp.3370-3377
• /
• 2015

전동차는 대용량 교통수단으로서 정시 운행 및 높은 안전성이 요구되기 때문에, 고장 분석을 체계적으로 수행하여 신뢰도를 향상시키기 위한 수단으로서 고장 영향의 심각도 및 치명도를 정량적으로 평가하는 FMECA (Failure Modes, Effects and Criticality Analysis) 기법이 적용되고 있다. 그러나, 아직까지 전동차에 특화된 FMECA 규격 및 절차는 정립되어 있지 않고 자동차 산업 등 다른 산업분야의 FMECA 규격을 그대로 적용하고 있기 때문에 전동차의 고유한 운영 및 유지보수 여건을 충분히 반영하지 못하고 있다. 본 논문에서는 산업계 각 분야에서 적용되고 있는 FMECA 규격에 대한 분석을 토대로, 전동차 분야에 적합한 FMECA 기법으로서 고장 영향 분석과 치명도 분석을 단계별로 나누어 수행하고 고장 영향의 심각도에 중점을 두어 치명도를 분석하는 기법을 제시하였다. 제안 기법을 전동차의 핵심 안전 장치인 고속차단기에 적용하여 도시철도 현장에서의 15년 동안의 전동차 유지보수 데이터를 이용하여 분석한 결과, 고속차단기 부품 중에서 특히 아크 슈트의 절손이 심각도 3등급, 치명도 5등급으로 위험도가 가장 높았으며, 뒤를 이어서 전자변 파손 및 접촉 불량, 실린더 파손 등이 심각도 3등급, 치명도 4등급으로 위험도가 높은 것으로 나타났다. 이상의 분석 결과는 전동차 고속차단기의 설계 및 유지보수 업무의 개선에 활용할 수 있다.

• Journal of Chest Surgery
• /
• 제25권7호
• /
• pp.693-701
• /
• 1992

Extracorporeal cardiopulmonary bypass[CPB] has been associated with a wide variety of hematologic derangements, including a transient deformation and hemolysis of red blood cells[RBCs], which is supposed to be due to mechanical trauma and/or metabolic alterations. Since membrane integrity is, in part, maintained by energy requiring process, inadequate function of erythrocyte glycolytic pathway, which is inevitalble during CPB, may cause depletion of high energy phosphate pool and result in hemolysis. The authors performed an investigation to assess whether administration of Fructose-l, 6-diphsphate [FDP], which has been known to enhance intracellular glycolytic activities, could counteract erythrocyte hemolytic events caused by CPB. Sixty pateints with cyanotic congenital heart diseases, who underwent open heart surgery under CPB longer than 60 minutes, were randomly divided into two groups depending on whether use of FDP[Group FDP] or not[Group Control]. The age, sex, CPB time, preoperative hemoglobin level, disease entities were all similar[Table 1], and membrane type oxygenators were used in all patients. In Group, FDP, a dose of 250mg/kg body weight of FDP was administered by intravenous dripping every 12 hours from the morning of the operation to postoperative 48 hours, To demonstrate the degree and pattern of hemolysis of erythrocyte, reticulocyte count, indirect /direct bilirubin, haptoglobin, plasma hemoglobin, lactate dehydrogenase were measured every 12 hours from the time of cessation of CPB to 48 hours and RBC morphologic study, osmotic fragility test were done every 24 hours. All parameters revealed less hemolytic in group FDP [Fig. 1~5], though the differences between two groups were not significant, except plasma hemoglobin, lactate dehydrogenase changes. A pattern of sequential changes of plasma hemoglobin, lactate deh-ydrogenase showed the highest level at the time of CPB stop and abrupt decrease in following 24 hours in both groups, and statistically significant differences were demonstrated in group FDP at least for the first 12 hours postoperatively[p<0.05]. The authors conclude that they can expect the benificial effect of FDP on the maintenance of membrane stability of RBC probably by energy enhancement during the shock status of CPB, but FDP could not completely prevent the damaging effect on RBC by cardiopulmonary bypass

• 융합보안논문지
• /
• 제13권3호
• /
• pp.55-62
• /
• 2013

시스템엔지니어링은 오늘날의 기업에 무척 중요하며 요구공학은 전반적인 과정상 중요한 단계이다. 요구공학은 고객으로부터 요구사항을 도출하고 문서화하는 것으로 시스템 개발의 첫 번째 단계이며, 시스템을 설계 제작하고 시험하고, 운영 유지하는 모든 과정이 요구사항에 관련되어 있어 프로젝트 성공의 매우 중요한 사항으로 평가된다. 프로젝트 성공을 위해 빈약한 요구사항을 최소화하도록 객체 지향 요구공학이 제안되어 졌다. 객체 지향 요구공학은 요구사항 각각에 대하여 기능성은 물론 제품과 프로세스에 대한 정보를 통합하여 관리하는 접근방식이다. 본 논문은 객체 지향적 요구사항 관리의 모범인 OCH(Operations Concept Harbinger)의 개념 적용을 통하여 사용자 요구 수집단계에서 다양한 이해관계자의 의견을 동시에 통합적으로 수렴하여 사용자 요구를 요구사항으로 전환하고 요구사항별로 추적함으로써 무기체계 획득을 위한 정확한 요구사항 개발과 관리를 가능케 하고 사용자 요구누락 및 왜곡을 방지하며 통합적 프로젝트 관리가 가능토록 제안하는 것이다.

• 한국안전학회지
• /
• 제33권1호
• /
• pp.66-72
• /
• 2018

This study analyses the types, related operations, facilities, and causes of chemical accidents in Korea based on the RISCAD classification taxonomy. In addition, human error analysis was carried out employing different human error classification criteria. Explosion and fire were major accident types, and nearly half of the accidents occurred during maintenance operation. In terms of related facility, storage devices and separators were the two most frequently involved ones. Results of the human error-based analysis showed that latent human errors in management level are involved in many accidents as well as active errors in the field level. Action errors related to unsafe behavior leads to accidents more often compared with the checking behavior. In particular, actions missed and inappropriate actions were major problems among the unsafe behaviors, which implicates that the compliance with the work procedure should be emphasized through education/training for the workers and the establishment of safety culture. According to the analysis of the causes of the human error, the frequency of skill-based mistakes leading to accidents were significantly lower than that of rule-based and knowledge based mistakes. However, there was limitation in the analysis of the root causes due to limited information in the accident investigation report. To solve this, it is suggested to adopt advanced accident investigation system including the establishment of independent organization and improvement in regulation.

• 산업진흥연구
• /
• 제8권4호
• /
• pp.37-46
• /
• 2023

화학설비의 노후화·고도화·복합화 등으로 인해 설비의 점검, 보수 또는 정비 작업 등의 비일상 작업이 증가하고 있으며, PSM 대상 화학제품제조업 사업장에서의 지난 10년간 발생한 1,483건의 사고 중 비일상 작업 중에 발생한 사고가 전체의 56%(932건)를 차지하여 일상 작업보다는 비일상 작업 중에 더 많은 사고가 발생하는 것을 확인할 수 있다. 특히 공장 운전의 경제성 및 효율성을 위하여 공장 전체를 정지시키지 않고 일부 설비를 정지시킨 후 운전 중인 설비와는 격리한 상태로 점검, 보수 또는 정비 작업을 수행하는 경우가 있다. 따라서 첫째, 화학공장의 취급물질, 운전조건, 설비의 위험도 등을 기준으로 격리 표준(Baseline Isolation Standard)을 수립하여 안전한 격리 방안을 선정하여야 한다. 둘째, 현재 국내 법규 및 기준 상에는 구체적인 격리 표준의 필요성을 제시하지 않고 있으므로 격리 표준의 마련을 제도화하는 것이 필요하다. 이러한 기술적·제도적 개선을 통하여 화학공장 설비에서의 화학물질의 누출에 의한 화재·폭발·중독 사고를 예 방하여야 한다.