• Clean Technology
• /
• v.7 no.2
• /
• pp.99-107
• /
• 2001

Optimization methodologies have been proposed of find the best environment-friendly recycling pathways of plastic materials based on life-cycle assessment (LCA) methodology. The main difficulty in conducting this optimization study is that multiple environmental burdens have to be considered simultaneously as the cost functions. Instead of generating conservative Pareto or noninferior solutions following multi-objective optimization approaches, we have proposed some practical criteria on how to combine the different environmental burdens into a single measure. The obtained single objective optimization problem can then be solved by conventional nonlinear programming techniques or, more effectively, by a tree search method based on decision flows. The latter method reduces multi-dimensional optimization problems to a set of one-dimensional problems in series. It is expected the suggested tree search approach can be applied to many LCA studies as a new promising optimization tool.

• Clean Technology
• /
• v.19 no.4
• /
• pp.459-463
• /
• 2013

Recent rapidly growth in nanotechnolgies is promised novel benefits through the exploitation of their unique industrial and biomedical applications. In addition, these nanomaterials and nano-consumer products have increased in quantity per year, and thus their uncontrolled release into the environment is anticipated to grow dramatically in future. Many papers for cytotoxicity of nanomaterials have been already reported, and thus government supports has funded to various research topics for nanosafety. Herein, we analyzed the importance and performance of nanosafety researches and tried to show the research direction where we have to go.

• Clean Technology
• /
• v.6 no.2
• /
• pp.101-106
• /
• 2000

A new nonvolatile and nonflammable soldering flux was developed. This flux was synthesized with dichloropropane as its solvent instead of VOC solvents such as isopropanol and methanol etc. which had been used in the conventional flux. It was confirmed that the nonflammable and nonvolatile flux(NFV-flux) was better in insulation resistance, workability, and reliability and that it was better in the enviromment and safety of the working place and more economic in comparison with the conventional flux.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.870-875
• /
• 2004

In Japan, a long-waited civil aero engine development project has been recently started by the New Energy and Industrial Technology Development Organization, NEDO. “High efficiency,” “environmentally friendliness” and “low-cost” are the key words of the target engine. The target engine is of l0000-lb thrust with project consists of three phases: Feasibility studies and market research in the first phase, FY 2003, engine component development in the second phase, FY 2004-2006, and core and full engine demonstrators in the third phase, FY 2007-2009. In league with this government/industry joint funded project, Institute of Space Technology and Aeronautics, JAXA, has initiated “Clean Engine Technology” project.

• MALSORI
• /
• no.60
• /
• pp.181-190
• /
• 2006

This paper describes a speech enhancement scheme that leads to significant improvements in recognition performance when used in the ASR front-end. The proposed approach is based on adaptive comb filtering and an MMSE-related parameter estimator. While adaptive comb filtering reduces noise components remarkably, it is rarely effective in reducing non-stationary noises. Furthermore, due to the uniformly distributed frequency response of the comb-filter, it can cause serious distortion to clean speech signals. This paper proposes an improved comb-filter that adjusts its spectral magnitude to the original speech, based on the speech absence probability and the gain modification function. In addition, we introduce the modified comb filtering-based speech enhancement scheme for ASR in mobile environments. Evaluation experiments carried out using the Aurora 2 database demonstrate that the proposed method outperforms conventional adaptive comb filtering techniques in both clean and noisy environments.

• Journal of the Korean Institute of Rural Architecture
• /
• v.5 no.2
• /
• pp.33-41
• /
• 2003

Through the courses of industrialization, speedy growth and pluralism. The problems about the environment- friendly structures have become very important problem. Especially, it is getting highly appear to the expectation about the environment friendly buildings in Kangwon-do where has greacefully clean environment. The guide line for Kangwon-do can be arranged to the following through the varity analysis, outside enviroment, color, construction materials, outside design etc the guide line for Kangwon-do can be arranged as to the followings. It appears to be suitable to country houses in kangwon-do that is made of timber or red-bricks with green half circled roof and give a sense of warmth and soft. but the coastal area village is appeared wave style roof with orange color and surrounded by natural building stones or a line- plastered wall making complicated.

• Clean Technology
• /
• v.26 no.3
• /
• pp.177-185
• /
• 2020

All coal ash, generated from coal-fired power plants, is entirely dumped onto a landfill site. As coal ash contains 80% fly ash, a clean floating process was developed in this study to recover useful components from coal ash and to use them as high value-added industrial materials. When the unburned carbon (UC) was recovered from the fly ash, soybean oil, an eco-friendly vegetable oil, was used as collector instead of a non-ionic kerosene collector to prevent the occurrence of odor from the kerosene. After the UC was separated by flotation, particulate ceramic microsphere (CM) was recovered, without generating acidic wastewater, through hydro-cyclone instead of sulfuric acid solution in order to separate ceramic microsphere (CM) and cleaned ash (CA) from the residue. By utilizing soybean oil as a collector, the recovery rate of UC turned high at 85.8% due to the increased adsorption of UC, the high viscosity of soybean oil, and the increase in floating properties caused by the linoleic acid contained in soybean oil. All of the combustible components contained in the recovered UC were carbon components, with the carbon content registering high when soybean oil was used. The recovered UC had many pores with a rough surface; thus, it could be easily ground and then used as an industrial material for its fine particles. The CM and CA recovered by the clean separation process using hydro-cyclone had a spherical shape, and the particles were clearly separated without clumping together. The average diameter (D₅₀) of the particles was 5 ㎛, so it was possible to realize the atomization of CM through a process change.

• Korean Chemical Engineering Research
• /
• v.52 no.1
• /
• pp.58-62
• /
• 2014

Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range $400{\sim}600^{\circ}C$ and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was $3.67{\times}10^{-11}mols^{-1}cm^{-2}$ with 0.1% faradaic efficiency at $600^{\circ}C$.

• Journal of the Korean housing association
• /
• v.21 no.6
• /
• pp.99-108
• /
• 2010

This study investigated the environmental indices in environmental administration, and to presents how to develop a sustainable environmental evaluation index. The index should be used to evaluate composite plans in the environmental aspects as well as means for setting goals of basic plans for the environment and its management. Specifically, the goals of composite plans are to check environments and land use frame, and evaluate individual measures (public projects). Environment policies are required to be 'a policy creating a clean environment' from 'a policy of environment regulation'. For the organization of a basic framework of environment policies, five topics are needed to be considered, such as the clarification of the idea of environment, establishment of environment regulations, environment management plan, plan to support civilian's action, and local government's efforts for the global matters of environment. For the amenity environments, people should expand their environmental behavior based on their voluntary intentions in transformation of personal life styles, projects with less load on the environment, development of environmentally-friendly projects with consideration for their impact on the earth. This study suggests that they should put more efforts into the development and implementation of useful environmental indices which effectively analyse the regional character to protect the natural ecology and create an sustainable environment with wide coverage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.9
• /
• pp.579-588
• /
• 2010

According to the increasing concern about health and environment, students need to study in comfort and clean environment facilities. We did field survey on 40 primary schools to analyze the present condition of design and construction for the part of indoor environmental performance in the certificated green school building. We hope that this paper will offer the important data about the indoor environment standards and performances in primary school facilities.