• 멤브레인
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• 제12권3호
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• pp.182-191
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• 2002

복합 박막의 구조를 갖는 폴리아미드계 역삼투 분리막은 상용화되어 해수담수화 공정에 널리 적용되어져 왔다. 최근 고압·고회수율 공정은 기존의 해수 담수화 공정에 비해 에너지 비용 및 전처리의 규모의 측면에서 절감 효과를 가진다는 결과들이 발표되어왔다. 고압·고회수율 공정은 에너지 회수, 고압 펌프 설비, 그리고 고압 고염제거율의 역삼투막 개발에 의해 가능해 졌다. 본 연구에서는 기존의 해수담수화 공정에 사용되는 역삼투 분리막에 대한 고압·고회수율 공정 조건에서의 투과 성능을 조사하였다. 역삼투 분리막 평막의 평가에는 3.5%의 NaCl 수용액을 인공해수로 조제하여 실시하였으며 역삼투 분리막 모듈의 평가는 마산시 합포해변에서 자연 해수를 직접 사용하였다. 그 결과로 고압 고회수율 공정에 적합한 역삼투막은 고압에 대한 내압성을 갖는 역삼투막임을 보여준다. 고농축수에 대한 염제거율은 고압 운전에 의해 자연 향상되는 경향을 나타내었다.

• Journal of Preventive Medicine and Public Health
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• 제53권3호
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• pp.205-210
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• 2020

Objectives: Aging is assumed to be accompanied by greater health care expenditures. The objective of this retrospective, bottom-up micro-costing study was to identify and analyze the variables related to increased health care costs for the elderly from the provider's perspective. Methods: The analysis included all elderly inpatients who were admitted in 2017 to a hospital in Tehran, Iran. In total, 1288 patients were included. The Mann-Whitney and Kruskal-Wallis tests were used. Results: Slightly more than half (51.1%) of patients were males, and 81.9% had a partial recovery. The 60-64 age group had the highest costs. Cancer and joint/orthopedic diseases accounted for the highest proportion of costs, while joint/orthopedic diseases had the highest total costs. The surgery ward had the highest overall cost among the hospital departments, while the intensive care unit had the highest mean cost. No statistically significant relationships were found between inpatient costs and sex or age group, while significant associations (p<0.05) were observed between inpatient costs and the type of ward, length of stay, type of disease, and final status. Regarding final status, costs for patients who died were 3.9 times higher than costs for patients who experienced a partial recovery. Conclusions: Sex and age group did not affect hospital costs. Instead, the most important factors associated with costs were type of disease (especially chronic diseases, such as joint and orthopedic conditions), length of stay, final status, and type of ward. Surgical services and medicine were the most important cost items.

• KEPCO Journal on Electric Power and Energy
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• 제6권1호
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• pp.53-58
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• 2020

Korea Electric Power Corporation (KEPCO) uses large amount of SF₆, one of the potent greenhouse gases, in electric equipment for electrical insulation. KEPCO is developing SF₆ recovery and purification technology to minimize the release of SF₆ into the environment, to secure certified emission reduction, and to save purchase cost of new SF₆ by reusing the refined SF₆. A prototype SF₆ purification system using cryogenic solidification technology has been built in demonstration scale. To evaluate the feasibility of the commercialization, the system has been operated to purify large amount of used SF₆ in a long-term operation and the performance has been economically evaluated. The system was stable enough for commercial operation such that it was able to purify 5.4 tons of used SF₆ from power transmission equipment in 2-month operation. Over 99% of the SF₆ was recovered from the used gas and the purity of the purified gas was over 99.7 vol%. The operation cost, which is the cost of refrigerant (liquid nitrogen), electricity and labor, per kilogram of purified SF₆ was 6,526 KRW. Considering the price of new SF₆ in Korea is about 15,000 KRW per kilogram this year, about 56% of the purchase cost can be saved.

• 한국추진공학회지
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• 제23권4호
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• pp.1-9
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• 2019

최근 위성발사체 시장에서 발사가격은 상당한 수준으로 낮아지고 있다. 이것은 약 10년전부터 발사 시장에 SpaceX 등의 민간기업이 진입하면서 소수 기업의 독점체제가 민간을 포함한 경쟁체제로 변하였고, 민간기업의 기술 및 경영 효율화가 적극적으로 도입되고 있기 때문이다. 또한 SpaceX는 2016년에 위성발사체 1단의 회수에 성공함으로써 재사용발사체의 서막을 열었고, 향후 재사용발사체를 활용하여 위성발사 가격을 획기적으로 낮추겠다고 공언하고 있다. 본 연구에서는 어떤 한 위성을 LEO 궤도에 올리기 위하여 필요한 총 발사비용을 계산하고, 3가지 경우의 임무중량에 대하여 각각의 발사비용을 비교하여 재사용발사체의 비용 효용성에 미치는 임무중량의 영향에 대하여 알아본다. 발사비용은 개발비용, 제작비용, 재사용비용, 운용비용, 고정비용 및 보험비용으로 구분하여 계산하며, 각 계산에 사용된 비용추정관계식은 TRNSCOST 등의 비용계산모델을 활용하여 사용하였다.

• 설비공학논문집
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• 제24권8호
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• pp.646-655
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• 2012

This study is intended to analyze the thermal performance and evaluate the applicability about non-duct type heat recovery ventilation system integrated with window. Eventually, economic analysis of the system is conducted according to building energy saving ratio of it. As results of the thermal performance, the U-factor of the window conducted on the basis of KS F 2278 appears to $1.8W/m^2K$, and the effective heat exchange efficiency of the ventilator conducted on the basis of KS B 6879 appears 49.95% for cooling, 66.89% for heating. In the applicability evaluated by TRNSYS 16, the caes of applying the heat recovery ventilator integrated with window is found to reduce the cooling or heating load by 2.9% or 13.5% than the non-ventilator case. The results of economic analysis taking a side of consumer is verified as the payback is 3 years, and the accumulated earning is 1,408,133 won in terms of '600,000 won/unit' for initial cost, 10 years for useful life of the system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.80-83
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• 2001

According to the EPA in Taiwan report, 9.05 million metric tons of solid wastes were generated in 1999, and the waste glass was accounted of 4.95 percent. However, with the increasing tonnage of disposal cost and existing disposal sites are reaching full capacity, recycling is currently accepted as a sustainable approach to waste management. Therefore, it's essential and urgent that the government in Taiwan establish the recycling and recovery framework for the minimization of the solid waste, reduction of materials and energy consumption, and the encouragement for the reuse, recycle and recovery development. To achieve this Boal, Taiwan has been strived for a long period of time in waste glass recovery and recycle. Waste glass, unlike other kinds of resource waste, is 100% recyclable. The EPA in Taiwan now center on a lot of different kinds of waste glass, such as glass container, flat glass, CRT glass, windshields glass, fluorescent lamps, and waste pesticide glass container. This article will focus on the framework of the recycling market access, and also try to provide some strategies to improve waste glass recycling efficiently.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.996-1001
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• 2009

The purposes of this work were suggested and validated the methods of heat recovery from dyeing wastewater exhausted in Sihwa and Banwol dyeing industrial park. We analyzed the present conditions of heat supplies and demands. So it was made a selection of the system combined heat exchanger for waste heat recovery and the high temperature heat pump. We decided the specifications of the heat recovery facilities. After this, economical assessment is performed to this system. The payback periods are within 4 years, 20 years and 5 years in case of K company, S company and A company. In addition, when they are produced the heat of same capacity, quantities of pollutants from used fuels were calculated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.5103-5115
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• 2015

In radar imaging, a target is usually consisted of a few strong scatterers which are sparsely distributed. In this paper, an improved sparse signal recovery algorithm based on smoothed l₀ (SL0) norm method is proposed to achieve high resolution ISAR imaging with limited pulse numbers. Firstly, one new smoothed function is proposed to approximate the l₀ norm to measure the sparsity. Then a single loop step is used instead of two loop layers in SL0 method which increases the searching density of variable parameter to ensure the recovery accuracy without increasing computation amount, the cost function is undated in every loop for the next loop until the termination is satisfied. Finally, the new set of solution is projected into the feasible set. Simulation results show that the proposed algorithm is superior to the several popular methods both in terms of the reconstruction performance and computation time. Real data ISAR imaging obtained by the proposed algorithm is competitive to several other methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.942-943
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• 2008

The boost converter is usually used in power factor correction. The dynamic losses of its output diode are produced during the reverse recovery time. The power efficiency is decreased due to the losses and also it generates the noise. These disadvantages have been remarkably improved by ZCS and ZVS techniques of power factor improvement circuit. Some benefits lead to the achievement of higher power density and the development cost can be decreased. In this paper work, the reverse recovery suppression(RS) PFC method is used. A inductor and a diode are added into the conventional circuit. The switching device, MOSFET is turned off after the reverse recovery current has come to the zero level. The Zero Current Switching(ZCS) is implemented at that time. This power conversion technique improves the efficiency to about 1% and reduces the noise obviously. And the additional inductor can be designed using an original filter core in the circuit. The converter size is reduced effectively.

• 전력전자학회논문지
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• 제17권2호
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• pp.107-113
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• 2012

This paper proposes a PDS(Power Transfer Display separation) method for AC-PDP. The proposed PDS method can transfer power and perform an energy recovery by a power conversion circuit operates differently depending on the time. As a result, it uses less of components than conventional PDP power supply and sustain circuit use. Moreover, the manufacturing process can be streamlined. Therefore, the proposed method is suitable for low cost PDP module. To confirm the operation, validity and features of the proposed PDS method, experimental results from a prototype for 42-in diagonal PDP are presented.