• 상하수도학회지
• /
• 제36권2호
• /
• pp.59-79
• /
• 2022

Conventional wastewater treatment plants (WWTPs) do not fully remove micropollutants. Enhanced treatment of sewage effluents is being considered or implemented in some countries to minimize the discharge of problematic micropollutants from WWTPs. Representative enhanced sewage treatment technologies for micropollutant removal were reviewed, including their current status of research and development. Advanced oxidation processes (AOPs) such as ozonation and UV/H₂O₂ and adsorption processes using powdered (PAC) and granular activated carbon (GAC) were mainly discussed with focusing on process principles for the micropollutant removal, effect of process operation and water matrix factors, and technical and economic feasibility. Pilot- and full-scale studies have shown that ozonation, PAC, and GAC can achieve significant elimination of various micropollutants at economically feasible costs(0.16-0.29 €/m³). Considering the current status of domestic WWTPs, ozonation and PAC were found to be the most feasible options for the enhanced sewage effluent treatment. Although ozonation and PAC are all mature technologies, a range of technical aspects should be considered for their successful application, such as energy consumption, CO₂ emission, byproduct or waste generation, and ease of system construction/operation/maintenance. More feasibility studies considering domestic wastewater characteristics and WWTP conditions are required to apply ozonation or PAC/GAC adsorption process to enhance sewage effluent treatment in Korea.

• 한국산업융합학회 논문집
• /
• 제25권6_2호
• /
• pp.1097-1102
• /
• 2022

With the continuous development of the current industry, the current global environment is in a very serious situation, with resource supply and demand dependent on imports and huge costs for waste disposal due to the depletion of resources and mass generation of industrial waste. Its limitations have already been revealed in many fields, and the importance of re-manufacturing is drawing attention as a countermeasure to these problems. Re-manufacturing aims to recover products that are in the aging and disposal stages, recover to performance close to new products, and re-commercialize them. Among them, most of the machine tools are made of materials such as steel and cast iron with large structures, and raw materials are widely used when producing new products. In addition, since a lot of carbon is generated due to production, it is an object that can obtain a great re-manufacturing effect. Planner millers belonging to large machine tools are one of the machine tool equipment that can greatly reduce resources and energy through re-manufacturing because the structure is very large and the casting is several to tens of tons. Through this machine tool, performance tests and results are derived on the development of re-manufacturing source technology and domestic servo motor and CNC control device.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2001년도 추계학술발표회 초록집
• /
• pp.68-68
• /
• 2001

Thin films of polycrystalline silicon (poly-Si) is a promising material for use in large-area electronic devices. Especially, the poly-Si can be used in high resolution and integrated active-matrix liquid-crystal displays (AMLCDs) and active matrix organic light-emitting diodes (AMOLEDs) because of its high mobility compared to hydrogenated _amorphous silicon (a-Si:H). A number of techniques have been proposed during the past several years to achieve poly-Si on large-area glass substrate. However, the conventional method for fabrication of poly-Si could not apply for glass instead of wafer or quartz substrate. Because the conventional method, low pressure chemical vapor deposition (LPCVD) has a high deposition temperature ($600^{\circ}C-1000^{\circ}C$) and solid phase crystallization (SPC) has a high annealing temperature ($600^{\circ}C-700^{\circ}C$). And also these are required time-consuming processes, which are too long to prevent the thermal damage of corning glass such as bending and fracture. The deposition of silicon thin films on low-cost foreign substrates has recently become a major objective in the search for processes having energy consumption and reaching a better cost evaluation. Hence, combining inexpensive deposition techniques with the growth of crystalline silicon seems to be a straightforward way of ensuring reduced production costs of large-area electronic devices. We have deposited crystalline poly-Si thin films on soda -lime glass and SiOz glass substrate as deposited by PVD at low substrate temperature using high power, magnetron sputtering method. The epitaxial orientation, microstructual characteristics and surface properties of the films were analyzed by TEM, XRD, and AFM. For the electrical characterization of these films, its properties were obtained from the Hall effect measurement by the Van der Pauw measurement.

• Geomechanics and Engineering
• /
• 제33권1호
• /
• pp.1-9
• /
• 2023

The unconfined compression strength (UCS) of soils is commonly used either before or during the construction of geo-structures. In the pre-design stage, UCS as a mechanical property is obtained through a laboratory test that requires cumbersome procedures and high costs from in-situ sampling and sample preparation. As an alternative way, the empirical model established from limited testing cases is used to economically estimate the UCS. However, many parameters affecting the 1D soil compression response hinder employing the traditional statistical analysis. In this study, gene expression programming (GEP) is adopted to develop a prediction model of UCS with common affecting soil properties. A total of 79 undisturbed soil samples are collected, of which 54 samples are utilized for the generation of a predictive model and 25 samples are used to validate the proposed model. Experimental studies are conducted to measure the unconfined compression strength and basic soil index properties. A performance assessment of the prediction model is carried out using statistical checks including the correlation coefficient (R), the root mean square error (RMSE), the mean absolute error (MAE), the relatively squared error (RSE), and external criteria checks. The prediction model has achieved excellent accuracy with values of R, RMSE, MAE, and RSE of 0.98, 10.01, 7.94, and 0.03, respectively for the training data and 0.92, 19.82, 14.56, and 0.15, respectively for the testing data. From the sensitivity analysis and parametric study, the liquid limit and fine content are found to be the most sensitive parameters whereas the sand content is the least critical parameter.

• 한국전자통신학회논문지
• /
• 제18권4호
• /
• pp.661-668
• /
• 2023

농업용 시설하우스의 난방을 위해서는 많은 양의 연료가 필요하고, 최근 연료 가격의 상승으로 인하여 많은 농가가 난방 비용에 대한 부담을 겪고 있다. 본 논문은 산업용 굴뚝 폐열을 활용하여 인근에 있는 농업용 시설하우스 난방을 지원하는 공급시스템을 제안하고, 난방비 절감 모델 적용과 효과에 대해 분석한다. 굴뚝 폐열 시스템을 기반으로 시스템을 설계하였고, 제안한 모델을 기반으로 시설하우스 난방비 절감 모델 적용 및 효과 분석을 수행하였다. 고열의 굴뚝 폐열을 이용하면 인근 농가의 시설하우스 난방 공급에 활용이 가능하다는 것을 확인하였다. 산업단지 인근 대규모 시설하우스에 난방을 공급한다면 국내 농가의 생산성 향상 및 경쟁력 제고에 이바지할 것으로 기대된다.

• 한국수자원학회논문집
• /
• 제55권spc1호
• /
• pp.1271-1282
• /
• 2022

상수관망 최적설계는 사용자가 설정한 목적에 따라 다양하게 사용된다. 상수관망 최적설계는 비용의 최소화 및 관의 제작 시 발생하는 에너지 최소화 등 목적이 다양하게 존재한다. 본 연구에서는 Modified Hybrid Vision Correction Algorithm (MHVCA)을 기반으로 다양한 상수관망에 대한 비용 최적설계를 진행하였다. 또한 새로운 평가지표인 Best Rate (BR)를 제안하였다. BR은 K-mean Clustering Algorithm을 기반으로 개발된 평가지표이다. BR을 통해 상수관망 최적설계에 사용된 각 알고리즘의 최적 설계안 탐색 가능성에 대한 비교를 하였다. 다양한 관망에 대한 MHVCA의 최적설계 결과를 Vision Correction Algorithm (VCA) 및 Hybrid Vision Correction Algorithm (HVCA)과 비교하였다. MHVCA는 VCA 및 HVCA보다 낮은 비용의 설계안을 탐색하였다. 또한 MHVCA는 낮은 비용의 설계안을 탐색할 확률이 VCA 및 HVCA보다 높았다. MHVCA는 본 연구에서 적용한 비용 최소화를 위한 상수관망 최적설계 뿐만이 아닌 다양한 목적을 위한 상수관망 최적설계에 적용할 경우 좋은 결과를 나타낼 수 있을 것이다.

• Geomechanics and Engineering
• /
• 제31권3호
• /
• pp.249-263
• /
• 2022

The specially-shaped Polycrystalline Diamond Compact (PDC) cutter is widely used in drill bit design due to its advantages of high rock cutting efficiency, strong impact resistance and long service life in hard and abrasive formation drilling. A detailed understanding of rock cutting behavior of worn specially-shaped PDC cutter is essential to improve the drilling efficiency and decrease the drilling costs. In this paper, the theoretical models of two new principles (loading performance (LP) and cutting performance (CP)) are derived for evaluating the cutting process of worn specially-shaped cutter, the theoretical models consider the factors, such as cutter geometry, aggressiveness, stress state, working life, and rock cutting efficiency. Besides, the numerical model of heterogeneous granite is developed using finite element method combined with Voronoi tessellation, the LP and CP of 12 kinds of worn specially-shaped PDC (SPDC) cutters are analyzed. The results found that the mechanical specific energy (MSE) of worn cutters first increase and then decrease with increasing the cutting depth, and the MSE increase with the increase of back rake angle except for Conical cutter and Wedge-shaped cutter. From the perspective of CP, the worn PDC cutters are more suitable for the smaller cutting depths, and the back rake angle has little effect on the CP of the specially-shaped worn PDC cutters. Conical cutter, Saddle-shaped cutter and Ellipse-shaped cutter have the highest CP value, while Rhombus-shaped cutter, Convex cutter and Wedge-shaped cutter have the lowest value in selecting cutters. This research leads to an enhanced understanding of rock-breaking mechanisms of worn SPDC cutters, and provides the basis to select of specially-shaped PDC cutters for the specific target formation.

• 멤브레인
• /
• 제33권6호
• /
• pp.305-314
• /
• 2023

화학 반응의 수율 향상을 위해 부산물을 제거하는 다양한 방법이 연구되고 있다. 특히 산업적으로 중요한 반응에서 주로 부산물로 물이 생성되기 때문에 넓은 범위의 온도에서 안정적으로 물을 분리하는 기술이 필요하다. 흡수제의 사용, 탈수 반응의 도입 등 다양한 방법이 제안되었으나 추가적인 에너지 및 시간 소요, 전환율의 지속 가능성 등의 문제로 한계를 가지고 있다. 그에 반해 운전 및 설치가 용이하고, 낮은 유지비용 등의 장점을 가지고 있는 분리막 기술은 다양한 촉매 반응에 도입되었을 때 안정적으로 부산물을 제거할 수 있어 반응의 효율을 향상시킬 수 있는 좋은 방안이다. 따라서 본 총설에서는 분리막을 이용한 부산물 제거 및 이를 통한 효과에 대해 논의하였다.

• 자원ㆍ환경경제연구
• /
• 제33권1호
• /
• pp.87-112
• /
• 2024

이 연구는 2019년 지역산업연관표와 지역별 및 산업별 온실가스 배출량을 추정하여 우리나라 온실가스 배출현황 및 탄소중립을 위한 탄소세 부과의 경제적 효과를 지역별 및 산업별로 분석하였다. 분석결과 제조업 중심의 광역자치도에서 온실가스 배출량, 배출계수 및 배출유발계수가 높게 추정되었다. 동일한 산업일지라 하더라도 온실가스 배출계수가 지역에 따라 다른 것으로 나타났는데, 이는 대분류 기준에 따른 상품 분류, 생산기술의 특성, 생산요소 투입구조의 지역별 차이 등에 기인하는 것으로 추정된다. 한편 탄소세가 부과될 경우 온실가스 배출량이 많은 제조업을 중심으로 생산비용이 상승하고 수요 및 생산이 감소할 것으로 예측되었다. 이에 비해 탄소세 부과가 각 지역에 미치는 영향은 지역별로 차이가 상대적으로 크지 않을 것으로 예측되었는데, 이는 지역별로 산업비중이 달라 탄소세 부과가 지역에 미치는 직접적인 영향이 다를지라도 산업연관효과에 의해 그 차이가 완화되기 때문인 것으로 판단된다. 이처럼 탄소세 부과의 영향은 특정 지역에 집중되지 않고 전 지역에 파급될 것으로 예상되는 만큼 향후 탄소중립 이행과정에서 지자체 간의 긴밀한 협조가 필요할 것으로 생각된다.

• 한국산업융합학회 논문집
• /
• 제27권1호
• /
• pp.207-212
• /
• 2024

Recently, with the strengthening of environmental regulations, there has been an increasing interest in eco-friendly energy sources, leading to a trend of the increasing scale of Cargo Containment Systems (CCS) for Liquefied Natural Gas (LNG) carriers. Among these systems, membrane tanks have gained popularity in LNG transport vessels due to their superior spatial utilization and competitiveness. However, due to high initial investment costs and the difficulty in repair in case of damage, a safety layer, the secondary barrier, must be installed without fail. In this study, in order to apply a new secondary barrier to the existing membrane-type LNG CCS, tests were conducted on the fiberglass layer previously used in the Triplex-Flexible Secondary Barrier (FSB), substituting it with basalt fiber. Tensile and vertical tensile tests were performed to assess the newly applied material. Environmental tests were conducted at room temperature (25℃) and extremely low temperatures (-170℃), considering the temperatures to which substances may be exposed during LNG vessel operations. The basalt-FSB produced in this study demonstrated superior results compared to the specifications of the existing product, confirming its potential applicability for implementation.