• 한국경제지리학회지
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• 제25권4호
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• pp.583-599
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• 2022

OECD는 저밀도 경제 논의에서 저밀도 지역의 경제 성장이 금융위기 이 후 회원국들의 국가 경제 회복을 견인했음을 밝혔다. 이 연구에서는 저밀도 경제 논의에 기초하여, 우리나라 주변부 지역의 산업 성장 추이와 공간적 특성을 살펴보았다. 그 결과 농림어업 등 주변부 지역에 입지하는 전통적인 산업 외에도 국가적으로 성장하는 제조업, 서비스업 부문의 성장이 주변부 지역에서 나타났다. 기존 지역 산업의 다각화와 전환을 통해 새롭게 산업이 집적하는 지역도 출현했다. 주변부 지역에 입지한 기업들은 지역의 불리함을 극복하기 위해 외부 지역, 주로 광역권 단위의 공간 연계를 형성하는 것으로 확인되었다. 주변부 지역의 새로운 산업 출현은 농어촌, 인구감소 지역 등 낙후 지역의 자생적 발전 가능성을 보여준다. 이러한 결과를 토대로 주변부 지역의 산업 육성을 위해, 기존 지역산업의 다각화를 지원하기 위한 정책 추진, 유연한 공간 단위 설정, 정책 부문 간 연계 등의 시사점을 도출하였다.

• 한국농촌건축학회논문집
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• 제3권3호
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• pp.57-67
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• 2001

The evolution of multi-family housing in Cheongju can be divided by four stages which are a introduction period from 1972 to 1980, a popularization period from 1981 to 1989, a expansion period from 1990 to 1997, and a stagnation period after 1998. In the introduction period, the multi-family housings were mainly low-rise buildings because a government policy which focused on extension of the apartments for the low-income influenced multi-family housing constructions. During the popularization period, the multi-family housings were still low-rise but houses in various sizes were introduced. That was because the Housing Site Developments were started and private companies' participations followed them increasingly. As a result of vigorous participations of private companies and massive developments of housing sites, the multi-family housings in the expansion period started to show constructions of complex and trends of high density and high rising. Finally, in the stagnation period, a rate of the supply of the small houses, whose size was below $60m^2$ of exclusive, area was increased and extreme high-rise apartments emerged. High rising and density were the mainstream of the construction concepts. During this period, the growth of multi-family housing marked low. The reason was that a downturn in economy led private companies to shrink their constructions.

• 한국재료학회지
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• 제32권5호
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• pp.237-242
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• 2022

Designing and producing a low-cost, high-current-density electrode with good electrocatalytic activity for the oxygen evolution reaction (OER) is still a major challenge for the industrial hydrogen energy economy. In this study, nanostructured Fe-doped CuCo(OH)₂ was discovered to be a precedent electrocatalyst for OER with low overpotential, low Tafel slope, good durability, and high electrochemically active surface sites at reduced mass loadings. Fe-doped CuCo(OH)₂ nanosheets are made using a hydrothermal synthesis process. These nanosheets are clumped together to form a highly open hierarchical structure. When used as an electrocatalyst, the Fe-doped CuCo(OH)₂ nanosheets required an overpotential of 260 mV to reach a current density of 50 mA cm^-2. Also, it showed a small Tafel slope of 72.9 mV dec^-1, and superior stability while catalyzing the generation of O₂ continuously for 20 hours. The Fe-doped CuCo(OH)₂ was found to have a large number of active sites which provide hierarchical and stable transfer routes for both electrolyte ions and electrons, resulting in exceptional OER performance.

• 동력기계공학회지
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• 제20권4호
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• pp.52-62
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• 2016

Nowadays, emissions of a vehicle are been getting by testing on a chassis dynamometer and a test modes. Also, fuel efficiency is calculated by carbon-balance method that is applying the emissions(CO, THC and $CO_2$) to the fuel calculation formular. In Korea, before 2014, the formular did not include the fuel factors (density, net heat value and carbon weight fraction), but the constants were based on the fuel properties of 2000s. So, this formular did not consider a characteristic of test fuel property that was changed when progressing fuel efficiency test. The characteristics of test fuel property which was distributed in domestic have a difference of quality depending on production regions and oil-refining facilities. Because the fuel properties are variable value during refineries, crude oils and blending contents of a bio-fuel, vehicle fuel is changed for each test. Therefore, the fuel qualities need to apply for a fuel economy test. In this paper, changing patterns of a fuel properties were reviewed during history of fuel standards. Also, the appropriateness of the methods was discussed by calculating and comparing fuel economies with the fuel factors and the constants.

• BMB Reports
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• 제33권2호
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• pp.148-154
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• 2000

The glycation process plays an important role in accelerated atherosclerosis in diabetes, and the uptake of atherogenic lipoproteins by macrophage in the intima of the vessel wall leads to foam cell formation, an early sign of atherosclerosis. Besides the lipolytic action on the plasma triglyceride component, lipoprotein lipase (LPL) has been reported to enhance the cholesterol uptake by arterial wall cells. In this study, some properties of LPL-mediated low-density lipoprotein (LDL) uptake and the effect of LDL glycation were investigated in RAW 264.7 cell, a murine macrophage cell line. In the presence of LPL, $^{125}I$-LDL binding to RAW 264.7 cells was increased in a dose-dependent manner. At concentrations greater than $20\;{\mu}g/ml$ of LPL, LPL-mediated LDL binding was increased about 17-fold, achieving saturation. Without LPL, both very low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) were ineffective in blocking the binding of $^{125}I$-LDL to Cells. However, LPL-enhanced LDL binding was inhibited about 50% by the presence of VLDL, while no significant effect was observed with HDL. Heat inactivation of LPL caused a 30% decrease of LDL binding. In the presence of LPL, the cells took up 40% of cell-bound native LDL. No significant difference was observed in cell binding between native and glycated LDL. However, the uptake of glycated LDL was significantly greater than that of native LDL, reaching to 70% of the total cell bound glycated LDL. These results indicate that LPL can cause the significant enhancement of LDL uptake by RAW 264.7 cells and the enhanced uptake of glycated LDL in the presence of LPL might play an important role in the accelerated atherogenesis in diabetic patients.

• 한국의류산업학회지
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• 제2권2호
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• pp.146-149
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• 2000

This study has been investigated the comparison of the seam strength of hand sewing with machine sewing using two kinds of sewing thread. On machine sewing, thread is used for sale, on hand sewing, thread is used for every fabric weft yarn. Breaking strength, efficiency and breaking mode of seams were examined under various sewing conditions using three kinds of fabric and three kinds of stitch type. The results obtained are as follows: The seam strength is not affected by sewing mechanism, but affected by a breaking mode : The type of slipped mode has a higher seam strength of hand sewing than that of machine sewing. When fabrics and threads were broken by a higher seam strength of machine sewing than that of hand sewing. Fabrics having low density using plain seam slipped more easily, so seam strength was greatly lesser. Fabrics having higher density had higher to seam strength. We should choose appropriate seams based on production, economy and aesthetics.

• 동력기계공학회지
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• 제21권3호
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• pp.12-18
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• 2017

Diesel and gasoline engines will be used as main power system of automobiles. Recently, engine downsizing is widely applied to both gasoline and diesel engines in order to improve fuel economy and exhaust emissions. Engine downsizing means small engine combustion chamber with higher combustion pressure. Therefore, spray and combustion process should be investigated under these high pressure and temperature conditions. In this study, constant volume combustion chamber which enables easy optical access from six directions was developed. Combustion chamber was designed to resist maximum pressure of 15 MPa and maximum temperature of 2,000 K. Combustible pre-mixed mixture was introduced into combustion chamber and ignited by spark plugs. High pressure and temperature were implemented by combustion of pre-mixed mixture. Three initial conditions of different pressure and density were tested. High repeatability of combustion process was implemented which was proven by low standard deviation of combustion pressure.

• 신재생에너지
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• 제3권1호
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• pp.46-53
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• 2007

Direct Methanol Fuel Cell, DMFC is a potential power source for portable IT application. DMFC works at low temperature ($<100^{\circ}C$) without fuel processing. Methanol has high energy density, fuel economy, and easiness to handle. This paper focuses high efficient catalyst to increase utilization in the electrode, new membrane reducing methanol crossover, new material parts, and optimization of system integration. Lightweight and small-sized DMFC based on new materials, efficient stack, and improved system control will be applied to the 50W prototype system for the notebook computer.

• 한국수소및신에너지학회논문집
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• 제31권6호
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• pp.578-586
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• 2020

There is growing interest worldwide in a hydrogen economy that uses hydrogen as an energy medium instead of hydrocarbon-based fossil fuels as a way to combat climate change. Since hydrogen has a very low energy density per unit volume at room temperature, hydrogen must be compressed and stored in order to use as an energy carrier. There are mechanical and non-mechanical methods for compressing hydrogen. The mechanical method has disadvantages such as high energy consumption, durability problems of moving parts, hydrogen contamination by lubricants, and noise. Among the non-mechanical compression methods, electrochemical compression consumes less energy and can compress hydrogen with high purity. In this paper, research trends are reviewed, focusing on research papers on electrochemical hydrogen compression technology, and future research directions are suggested.

• 전기화학회지
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• 제26권2호
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• pp.19-34
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• 2023

Due to the intermittency of renewable energy sources, a need to store and transport energy will increase. Hydrogen production through water electrolysis will provide an excellent way to supplement the intermittency of renewable energy sources. While alkaline water electrolysis is currently the most mature technology, it has drawbacks of low current density, large footprint, gas crossover, etc. The PEM water electrolysis has potential to replace the alkaline electrolysis. However, expensive catalyst material used in the PEM electrolysis has been the bottleneck of widespread use. In this review, we have reviewed recent efforts to reduce catalyst loading in PEM water electrolysis. In core-shell nanostructures, the precious metal catalyst forms a shell while heteroatoms form a core. In this way, the catalyst loading can be significantly reduced while maintaining the catalytic activity. In another approach, a corrosion-resistant support is utilized, which provides a stable platform to impregnate precious metal catalyst.