• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.981-986
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• 2015

As the seriousness of global environment pollution is gaining increasing public attention, research into greenhouse gas emissions of ships is being carried out globally. At a domestic level, however, in a number of significant fields such research has not been conducted to date. This study examined countermeasures for the reduction of $CO_2$ emission in the fields of electronic control engines, trim optimization, propeller polishing, hull cleaning, and anti-fouling paint using an actual sea-going vessel. Selected countermeasures were applied during sea trials of the ship and the effect of specific fuel oil consumption analyzed. It was found that each countermeasure resulted in a decrease of fuel consumption of 1~5%. The energy efficiency operational indicator (EEOI) was calculated and found to also be improved by 1~5%. Further research into the EEOI of domestic shipping is planned to enhance conformance with international environmental regulations and improve global competitiveness.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.3
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• pp.169-174
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• 2021

Today, plastic waste has become a critical social issue due to the increasing of plastic consumption. Korean annual per capita plastic consumption was 132 kg, the most plastic consuming country in the world. Internationally, Carbon Neutral Agreement is underway due to global warming, consumers' interest and needs for biomass-based plastics has also been increased. In this study, film was produced by adding composite use additives to the biomass-based plastics according to concentration, and the resulting changes in discharge volume, melt index, and tensile strength were investigated. Melt index (MI) was significantly higher in PLA and PBAT than in petroleum-based resin LLDPE and LDPE. Also, among the same resin or in the same treatment group, MI has been increased when the heating temperature is increased. The discharge volume and gravity of the BDP-2 to which 4% compatibilizer was added were found to be higher among all treatments, while the tensile strength of MD and TD was also higher. BDP-2 was suitable to the film producing methods for biodegradable film production.

• Journal of Korean Society of Forest Science
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• v.109 no.1
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• pp.31-40
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• 2020

This study aimed to investigate the effects of climate change on the survival and growth performance of Pinus densiflora and Larix kaempferi seedlings using open-field experimental warming and precipitation manipulation. We measured the survival rate, root-collar diameter, and height, and then calculated the seedling quality index (SQI) of 2-year-old seedlings under 6 treatments [2 temperatures (TC: Control; TW: Warming) × 3 precipitation manipulations (PC: Control; PD: Decreased; PI: Increased)] and performed a two-way ANOVA to test for differences.The air temperature of the warming plots was 3℃ higher than that of the control plots, while the precipitation manipulation plots received ±40% of the precipitation received by the control plots. Temperature and precipitation treatments did not significantly affect the survival rate of P. densiflora; however, the SQI of P. densiflora decreased with increasing precipitation. In contrast, the mortality rate of L. kaempferi increased with increasing temperature and decreasing precipitation. Furthermore, in L. kaempferi, TC × PI treatment resulted in the lowest SQI with a significant interaction effect observed between the two factors. In summary, low seedling production and quality should be expected in P. densiflora as precipitation increases and in L. kaempferi as temperature increases or precipitation decreases. These results indicate species-specific sensitivities to climate change of two plant species at the nursery stage. With the occurrence of global warming, the frequencies of drought and heavy rainfall events are increased, and this could affect the survival and seedling quality of tree species. Therefore, it is necessary to improve nursery techniques by establishing new adaptation strategies based on species-specific growth performance responses.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.143-152
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• 2009

The purpose of this study is to evaluate the freezing index and frost penetration depth. The freezing index and frost penetration depth were analyzed using air temperature and temperature profile of pavement system in Korea LTPP-SPS(Long Term Pavement Performance-Specific Pavement Study) site. The predicted frost penetration depth were then compared with the measured one from the LTPP sites. And the trend of annual freezing index was analyzed using the temperature data of meteorological stations located in the vicinity of Korea LTPP-SPS site. The result showed that the freezing index was rapidly decreased since 1987, and it was known that the use of freezing index determined from the past 30 years temperature data could cause the over estimates in the pavement thickness design. The temperature profile measured at 3 sections of LTPP-SPS sites showed that the temperature of subbase layer was above $0^{\circ}C$, even though anti-frost layers were found in these sections. Comparing the measured and calculated frost depth, the frost depth calculated from the subgrade frost penetration permissible method showed a similar trend with the measured frost depth.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.710-710
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• 2009

$SF_6$ 가스는 높은 절연 특성으로 인해 산업공정에서 순수 또는 $N_2$ 나 $CO_2$ 가스를 혼합시켜 광범위하게 사용되고 있다. 그러나 $SF_6$ 가스의 지구온난화지수는 $CO_2$ 대비 23,900배로 환경에 치명적인 영향을 줄 수 있으므로, $SF_6$ 가스에 대한 분리 및 처리에 관한 연구가 필요하다. 본 연구에서는 조성에 따른 $SF_6-N_2$ 혼합기체의 3상평형(물-하이드레이트-기체)점을 측정하였다. 측정결과 $N_2$가 더 많이 첨가된 혼합기체일수록 순수 $SF_6$의 상평형 조건보다 더 높은 압력, 더 낮은 온도에서 형성됨을 알 수 있었고 라만분석으로 실제 만들어진 하이드레이트 내에 혼합기체를 확인하였다. 또한 하이드레이트 형성속도 및 회수기체의 조성을 측정하여 분리 및 회수의 효율을 살펴보았다. 본 실험에서 얻어진 결과는 $SF_6$ 혼합기체의 분리 및 처리에 관한 연구의 중요한 기초 자료가 될 것이다.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.462-469
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• 2016

This paper presents the results of thermodynamic cycle analysis and performance tests of alternative mixtures in low temperature applications. Two near-azeotropic binary mixtures R-152a/R-1270 (35:65 by wt.%) and R-290/E170 (35:65 by wt.%) are considered in this study. They have zero ODP (Ozone Depletion Potential) and much lower GWP (Global Warming Potential) than R-404A which is an alternative of R-502. Refrigeration cycle characteristics such as cooling capacity, coefficient of performance, suction and discharge pressures and temperatures are compared to those for the baseline refrigerants (R-502 and R-404A) cycles. The performance tests are conducted at the evaporation and condensation temperatures of $5^{\circ}C$ and $45^{\circ}C$, subcooling and superheating temperatures of $5^{\circ}C$, respectively. Performance comparisons between baseline and alternative refrigerants are conducted on the same cooling capacity. The system performance of newly proposed refrigerant mixtures show promising results.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.223-225
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• 2008

하이드레이트는 저온.고압에서 저분자량의 게스트(guest)가 호스트(host)인 물분자 속에 포획되어 만들어지는데 일련의 과정은 물리적 반응을 통해 생성된다.본 연구에서는$CO_2$보다 지구온난화지수(Global Warming Potential)가 23,900배 높은 $SF_6$의 회수 및 정제기술로써 하이드레이트화를 이용하는 신기술 개발의 일환으로 분광학적 접근을 통해 $SF_6$ 혼합 하이드레이트의 정성 및 정량분석을 수행하였다. Raman Shift 분석 결과 $SF_6$의 $770cm^{-1}$에서 $v_1$ 진동주파수를 확인함으로써 하이드레이트 내 $SF_6$가 안정적으로 포집됨을 확인하였고 혼합가스 내 $SF_6$ 농도별로 만들어진 샘플의 Raman Shift를 통해서 $SF_6$의 하이드레이트 전환율을 가늠할 수 있었다.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.5
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• pp.415-420
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• 2018

The development of sail gas has increased the production of ethane as well as natural gas. The decline in the market price for ethane has led to a change in the petroleum-based ethylene production process into an ethane-based ethylene production process and an increase in the ethane/ethylene trade volume. Large-scale ethane/ethylene carrier have been needed due to an increase in long-distance trade from the US, and cargo type change have leaded to consider a liquefaction process to re-liquefy Boil-Off gas generated during the voyage. In this paper, the liquefaction system of Liquefied Ethane Gas carrier was evaluated with Low-GWP (Low-Global Warming Potential) refrigerant and process parameters, Boil-Off Gas pressure and expansion valve outlet pressure, were optimized. Low-GWP refrigerants were propane (R290), propylene(R1270), carbon dioxide(R744) was considered at two type of liquefaction process such as Linde and cascade cycle. The results show that the optimal pressure point depends on the individual refrigerant and the highest liquefaction efficiency of carbon dioxide (R744) - propane (R290) refrigerant.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.31 no.7
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• pp.29-31
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• 2002

생활수준의 향상과 산업의 고도화로 에어컨의 수요가 지속적으로 증가하고 있다. 표 1에 나타낸 바와 같이 2001년의 세계 에어컨 (가정용 및 패키지 에어컨) 수요량은 약 4000만대로 전체 생산 및 수요의 80% 이상을 아시아(중국, 일본, 한국)와 미국이 차 지하고 있다. 국내업체의 2001년의 국내외 총 에어컨 생산량도 700만대 정도로 전 세계 수요의 약 15% 이상을 점하고 있는데, 에어컨의 냉매에 의한 환경문제가 중요한 사안으로 대두되고 있다. 에어컨의 냉매로 사용되고 있는 HCFC계 (R22) 냉매의 대채냉매로 사용중인 HFC계 냉매도 지구온난화지수가 높으며, 1997년 채택된 교토 의정서에서 대기 배출가스 억제 물질로 분류되었다. 따라서, HFC물질을 사용하는 경우 제품 폐기시 냉매를 회수해야 하는 문제를 가지고 있어서 자연냉매의 사용에 대한 관심이 높아지고 있다. 이산화탄소도 자연냉매의 하나로 선진국을 중심으로 이산화탄소에 대한 이용기술 개발이 활발히 진행되고 있으며, 선진국에서는 이산화탄소 냉매를 적용한 급탕기와 같은 일부 상품이 출하되고 있다. 그러나, 이산화탄소 냉매를 이용한 냉난방시스템에 대해서는 선진국에서도 현재 실험실 차원의 시작품을 제작하여 성능과 신뢰성 향상을 위한 연구가 진행되고 있는 단계이며, 실용화를 위해서는 해결되어야 할 여러 가지 문제점들이 남아 있는 것으로 알려져 있다. 본 글에서는 산업자원부의 차세대신기술개발사의 일환으로 지원되고 있는 이산화탄소 냉매를 이용한 냉난방시스템의 개발 과제에 대해 간단히 소개하기로 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.12
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• pp.823-829
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• 2012

In this study, the performance of mobile air conditioner(MAC) systems to which the refrigerants R134a and R1234yf were used was evaluated to compare the characteristic of automotive refrigeration cycles with refrigerant. The experimental setup of a MAC consists of an belt driven compressor, a condenser, an evaporator and a block type thermal expansion valve. The drop-in test on MAC were carried out under variable compressor speed from 800 to 2500 rpm. Performance test by using R1234yf and R134a in the same system revealed low the charge amount and mass flow rates for using R1234yf, that is, up to 10% and 17%, respectively. The compressor discharge temperature of R1234yf is $8^{\circ}C$ lower than that of R134a. The cooling capacity with R1234yf system decreased by 4~7% compared with R134a system. In addition, The COP of R1234yf system is lower 3~4% than that of R134a system.