• 청정기술
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• 제30권2호
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• pp.71-93
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• 2024

최근, 무탄소 에너지원(특히, 선박 및 혼소 발전), 고효율 청정 수소 저장 및 매개체로써 암모니아가 다시 각광받고 있다. 암모니아는 화학공학에서 매우 중요한 공정 중 하나인 Haber-Bosch 공정을 통해 합성할 수 있지만, 이 공정은 에너지 소비량이 높고 탄소 배출량 역시 높아, 기존 공정을 통해 암모니아를 합성할 시 탄소 저감 효과가 미미하다. 이러한 기존 공정의 치명적인 단점을 해결하기 위해 최근, 높은 에너지 효율로 탄소 배출이 적게 암모니아를 합성할 수 있는 열화학적 합성 방법이 많이 개발되고 있다. 소재측면에서는 기존 공정보다 완화된 공정 조건에서도 충분히 높은 암모니아 합성 성능을 보일 수 있는 고성능 촉매 소재를 개발하는 연구가 진행되고 있으며, 공정측면에서는 매체 순환식(chemical-looping) 합성 방법, 플라즈마 합성방법, 기계화학적 합성 방식 등 다양하게 적용되고 있다. 이번 총설에서는 최근 청정수소 저장을 효과적으로 저장하기 위해 어떤 암모니아 합성 기술들이 개발되고 있는지 자세히 소개하고자 한다.

• 한국환경보건학회지
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• 제32권5호
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• pp.387-397
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• 2006

This study was performed to investigate the characteristics of indoor air quality(IAQ) in 91 public facilities from September 2004 to March 2005 in the Honam province(Chonnam, Gwangju). The measured air pollutants are $PM_{10}$, formaldehyde(HCHO), CO, $CO_{2}$ and total suspended bacteria(TSB), the maintenance standard materials of IAQ management law established by ministry of environment in Korea(MOE). We also surveyed establishment and operation of ventilation equipment. It was measured $1.2m{\sim}1.5m$ on the floor between 8 o'clock AM and 7 o'clock PM. As the result, $PM_{10}$ and CO was showed the highest concentration, $188.89{\mu}g/m^{3}$, 8.67 ppm, at the indoor parking. The concentration of HCHO was the highest in large store and steamer room. The concentration was respectively $118.70{\mu}g/m^{3}\;and\;113.21{\mu}g/m^{3}$. The concentration of $CO_{2}$ was the highest at the reading room of the library on the condition of natural ventilation. The concentration of $CO_{2}$ was 1,816 ppm and higher than the IAQ standards established by MOE. The TSB was just measured in the hospital and silver town. It was the highest at the admission room of hospital. The concentration of TSB was $766CFU/m^{3}$. The public facilities of this study were not exceed each maintenance standards except $CO_{2}$ but it was surveyed that the management will be needed about some air pollutant according to target facilities.

• 한국수소및신에너지학회논문집
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• 제32권6호
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• pp.565-572
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• 2021

Hydrogen is currently produced from natural gas reforming or industrial process of by-product over than 90%. Additionally, there are green hydrogens based on renewable energy generation, but the import of green hydrogen from other countries is being considered due to the output variability depending on the weather and climate. Due to low density of hydrogen, it is difficult to storage and import hydrogen of large capacity. For improving low density issue of hydrogen, the gaseous hydrogen is liquefied and stored in cryogenic tank. Density of hydrogen increase from 0.081 kg/m³ to 71 kg/m3 when gaseous hydrogen transfer to liquid hydrogen. Density of liquid hydrogen is higher about 800 times than gaseous. However, since density and boiling point of liquid hydrogen is too lower than liquefied natural gas approximately 1/6 and 90 K, to store liquid hydrogen for long-term is very difficult too. To overcome this weakness, this paper introduces storage method of hydrogen based on liquid/solid (slush) and facilities for producing slush hydrogen to improve low density issue of hydrogen. Slush hydrogen is higher density and heat capacity than liquid hydrogen, can be expected to improve these issues.

• 벤처혁신연구
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• 제6권4호
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• pp.23-40
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• 2023

본 연구는 빠른 속도로 디지털화 및 모바일화되는 리테일 산업에서 전통적인 오프라인 리테일러인 백화점을 대상으로 고객 가치 이론을 기반으로 백화점의 모바일 앱 지속 이용 의도에 영향을 미치는 고객 가치 요인을 조사한다. 본 연구에서는 다차원적인 고객 가치를 기능적 가치, 편의적 가치, 그리고 사회적 가치의 세 가지 차원으로 분류하였다. 기능적 가치는 옴니채널 리테일 환경에서의 채널 간 통합과 일관된 고객 경험 제공을 의미하며, 편의적 가치는 고객이 모바일 앱 이용 시 절약할 수 있는 시간과 노력의 절약인 편의성이다. 사회적 가치는 백화점의 모바일 앱 내 친환경 마케팅과 관련하여 제품 또는 서비스 사용으로 인해 발생하는 사회적 승인 또는 사회적 자아 개념의 향상을 뜻한다. 이렇게 세 가지 차원의 고객 가치를 선행변수로 하여 종속변수인 모바일 앱 지속 이용 의도에 미치는 각 영향력을 분석하였다. 국내 신세계 백화점의 모바일 앱 사용 이력이 있는 고객을 대상으로 데이터 수집 후 Smart PLS 4.0을 사용하여 실증 분석하였다. 분석 결과 고객 가치의 세 가지 차원인 기능적 가치, 편의적 가치, 사회적 가치가 모두 고객의 모바일 앱 지속 이용 의도에 정(+)의 영향을 미치는 것으로 나타났으며 기능적 가치의 영향력이 가장 큰 영향을 미친다. 기술의 발전으로인한 옴니채널 리테일 트렌드에서 기능적 가치가 가장 중요한 영향 요인으로 나타남에 따라 오프라인 리테일러인 백화점의 통합된 채널 제공이 중요하다는 점을 시사한다. 백화점 모바일 앱 활성화를 위한 고객 중심 전략 수립 방향에 대한 통찰력을 제공하며, 백화점이 기존 오프라인 채널이 아닌 신규 모바일 채널을 통해 변화하는 고객의 기대 및 요구를 효과적으로 충족할 수 있는 맞춤화된 서비스와 마케팅 활동을 위한 기초적인 분석자료를 시사한다.

• Asia pacific journal of information systems
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• 제25권4호
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• pp.763-783
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• 2015

Online customer reviews (i.e., electronic word-of-mouth) has gained considerable interest over the past years. However, a knowledge gap exists in explaining the mechanisms among the factors that determine the product sales in online retailing environment. To fill the gap, this study adopts a principal-agent perspective to investigate the effect of customer reviews and customer incentives on product sales in online retail stores. Two customer review factors (i.e., average review ratings and the number of reviews) and two customer incentive factors (i.e., price discounts and special shipping offers) are used to predict product sales in regression analysis. The sales ranking data collected from the video game titles at Amazon.com are used to analyze the direct effects of the four factors and the interaction effects between customer review and customer incentive factors to product sales. Result reveals that most relationships exist as hypothesized. The findings support both the direct and interaction effects of customer reviews and incentive factors on product sales. Based on the findings, discussions are provided with regard to the academic and practical contributions.

• Agricultural and Biosystems Engineering
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• 제3권2호
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• pp.65-72
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• 2002

Temperature is the most influential environment parameter which affects the quality change of agricultural products in cold storage. Therefore, it is essential to keep the uniform temperature distribution in the storage room. This study was performed to analyze the air movement and temperature distribution in the forced recirculating cold storage facility and to simulate optimum storage method of green groceries using 3-D CFD(three dimensional computational fluid dynamics) computer simulation which applied the standard $textsc{k}$-$\varepsilon$ turbulence model and FVM(finite volume method). The simulation was validated by the experimental results for onion storage and the simulation model was used to simulate the temperature and velocity distribution in the storage room with reference to the change of storage method such as location of storage, no stores, bulk storage, and pallet storage. In case of no stores, internal airflow was circulated without stagnation and consequently air movement and temperature distribution were uniform. In case of bulk storage, air movement was stagnated so much and temperature distribution of onion was not uniform. Furthermore, the inner temperature of onion roses more than the initial temperature of storage. In case of pallet storage, air movement and temperature distribution of onion were so uniform that the danger of quality change was decreased.

• 한국주거학회논문집
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• 제17권3호
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• pp.51-60
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• 2006

Ten years have passed since the Demolishing Walls Campaign has started in Daegu. Recently, the campaign influenced to the other cities in Korea, such as Seoul, Incheon and Busan with various names regarding cities' circumstances. In these context, the study aims to highlight the identity of the Demolishing Walls Campaign compare Daegu with other cities where similar movement has started. In addition, the study evaluates the campaign in terms of physical, psychological and economical aspects to suggest some practical suggestion for the development of the campaign based on questionnaire survey. The research findings are as follows. The research shows that the identity of the Daegu Campaign is started by bottom-up approach based on citizens' participation compare with others cities' campaigns which are mainly started by the local government so called top-down method. The Daegu campaign influences the local people aware of their potential abilities in positively improving urban environment. The results of survey also highlights the advantages of green spaces which by the campaign in terms of environmental and economical aspects. Newly generating urban greens accept and store heat which Influences urban microclimate conditions and it possibly affects energy savings of the city. Most of survey participants eager to continue this campaign which shows positive results in various aspects by the local people. Therefore, the city government building a coalition of local people, NGOs, and interest group to keep the identity of the campaign in Daegu.

• KIEAE Journal
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• 제10권1호
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• pp.91-96
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• 2010

Incheon Free Economic Zone's Songdo Area is a newly constructed city built on land reclaimed from the seaside and the surrounding area. Yeongjong Area is made after Land reclamation between Yeongjong Island and Yongyou Island began in November 1992. The first phase linking these islands to create the Incheon International Airport (phase 1) and the Airport Town Square community was finished in March 2001. However, if we take a look at the overall status of the project as it is carried on at present, it is hard to deny that the project is trapped inside the same legal restrictions as are all other existing cities, which permits Songdo Area and Yeongjong Area to meet only very minimum standards. This study intends to analyze and assess the Incheon Free Economic Zone's Songdo Area and Yeongjong Area of environmentally friendly construction and to rate its current development status, exposing any problems and offering alternative solutions. In this paper, the current state of constructions in Songdo Area and Yeongjong Area were reviewed. Then a quantitative analysis and assessment for the Songdo Area and Yeongjong Area constructions of apartments, complex buildings, office buildings, school facilities, store and hotel facilities were conducted by using green building certification criteria. Finally the synthetic results of environmental performance evaluation for Incheon Free Economic Zone's Songdo Area and Yeongjong Area constructions and follow-up suggestions were described.

• Membrane and Water Treatment
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• 제10권1호
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• pp.67-74
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• 2019

Apparent changes in the natural hydrologic cycle causing more frequent floods in urban areas and surface water quality impairment have led stormwater management solutions towards the use of green and sustainable practices that aims to replicate pre-urbanization hydrology. Among the widely documented applications are infiltration techniques that temporarily store rainfall runoff while promoting evapotranspiration, groundwater recharge through infiltration, and diffuse pollutant reduction. In this study, a laboratory-scale infiltration device was built to be able to observe and determine the factors affecting flow variations and corresponding solids removal through a series of experiments employing semi-synthetic stormwater runoff. Results reveal that runoff and solids reduction is greatly influenced by the infiltration capability of the underlying soil which is also affected by rainfall intensity and the available depth for water storage. For gravel-filled structures, a depth of at least 1 m and subsoil infiltration rates of not more than 200 mm/h are suggested for optimum volume reduction and pollutant removal. Moreover, it was found that the length of the structure is more critical than the depth for applications in low infiltration soils. These findings provide a contribution to existing guidelines and current understanding in design and applicability of infiltration systems.

• 한국항해항만학회지
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• 제47권2호
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• pp.85-92
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• 2023

The hardware of an LED lighting control system for coastal lighting at coastal pier entrance consists of a power supply unit, an AVR control unit, a CLCD output unit, an LED control unit, a scenario selection switch unit, and an operation speed display unit. It is made of an 8-channel. The CPU used ATmega128 and the FET was used to control the current signal. To operate the CPU, DC 12V was converted to DC 5V using a regulator 7805. A heat sink was used to remove heat generated in the FET. By connecting the load LED module to the manufactured 8-channel LED lighting control system, the operation was confirmed through various production scenarios. In addition, a control system was designed to show the most suitable color for the atmosphere of the coastal pier according to the input value of temperature and illumination using a fuzzy control system. Computer simulation was then conducted. Results confirmed that fuzzy control did not need to store many data inputs due to characteristics of artificial intelligence and that it could efficiently represent many output values with simple fuzzy rules.