검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 6

        1.
        2021.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, high temperature wetting analysis and AZ80/Ti interfacial structure observation are performed for the mixture of AZ80 and Ti, and the effect of Al on wetting in Mg alloy is examined. Both molten AZ80 and pure Mg have excellent wettability because the wet angle between molten droplets and the Ti substrate is about 10° from initial contact. Wetting angle decreases with time, and wetting phenomenon continues between droplets and substrate; the change in wetting angle does not show a significant difference when comparing AZ80-Ti and Mg-Ti. As a result of XRD of the lower surface of the AZ80-Ti sample, in addition to the Ti peak of the substrate, the peak of TiAl3, which is a Ti-Al intermetallic compound, is confirmed, and TiAl3 is generated in the Al enrichment region of the Ti substrate surface. EDS analysis is performed on the droplet tip portion of the sample section in which pure Mg droplets are dropped on the Ti substrate. Concentration of oxygen by the natural oxide film is not confirmed on the Ti surface, but oxygen is distributed at the tip of the droplet on the Mg side. Molten AZ80 and Ti-based compound phases are produced by thickening of Al in the vicinity of Ti after wetting is completed, and Al in the Mg alloy does not affect the wetting. The driving force of wetting progression is a thermite reaction that occurs between Mg and TiO2, and then Al in AZ80 thickens on the Ti substrate interface to form an intermetallic compound.
        4,000원
        2.
        2010.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Gas turbines for power generating operate in a very high temperature condition and use natural gas for fuel. For this reason, many cases of damage happen at hot gas parts which are severely affected by high temperature gas and many cases of explosion occur by fuel gas. So a lot of efforts should be made to prevent hot gas parts damage and gas explosion accidents. Though there are many damage cases and explosion accidents, it is very difficult to find out the root causes of hot gas parts damage caused by gas explosion due to gas leakage in the heat exchanger for air cooling and gas heating. To prevent gas turbine from damage caused by gas explosion, removal of leakage gas from gas turbine is inevitably required before firing the gas turbine and installing alarm systems is also required for detecting gas leakage at stop valve to turbine while shut down.
        4,000원
        3.
        2010.04 구독 인증기관 무료, 개인회원 유료
        Gas turbines generating power operate in high temperature condition and use natural gas as fuel. For that reason, there are many cases where damage is done to the hot gas parts caused by the high temperature and many accidents occur like gas explosions, then various efforts are needed to maintain the hot gas parts and prevent accidents. It is difficult to find the root causes of damage to the hot gas parts from the gas explosion caused by gas leakage through rotor cooling air line from fuel gas heat exchanger during the shut down. To prevent gas turbine from damage, removal of gas leakage inside of gas turbine is required by purging the turbine before firing, improving the fuel gas heating system and installing alarm systems for detecting gas leakage from stop valve to turbine while the gas turbine has shut down.
        4,800원
        4.
        2016.05 서비스 종료(열람 제한)
        Background : This experiment was conducted to find the right degree of shading to reduce summer months when the death Allium hookeri cultivation in the southern highland in Korea. This experiment was conducted at an altitude of 500m, Jeonbuk Namwon unbong plateau region The soil was tested in phosphatic content was slightly higher so 671 ㎎/㎏ than regular soil. Every soil testing was conducted in sandy soil with good water. The test day highs at 50% shading plots of shading in this period about 6.1℃ lower than the non-shading. The soil temperature is lowered to 1.9℃ at 50% shading plots compared with the non-shading. As a result, Allium hookeri underground quantities produced per 1,682 ㎏ 10a in 50% shading plots. This was a 35% increase compared to the non-shading plots. Allium hookeri is native to the Alpine 4,200m from 1,400m above sea level, near the Himalaya Mountains. Myanmar is known as the National vegetables. Allium hookeri is Allium plants. It flies three flavors, including sweet, spicy, bitter taste. Allium hookeri roots are similar to ginseng roots called as 'three vegetable' This is a randomly named. The in Korea was first introduced in 2006. By 2015, the country has been found to 190㏊, Jeonbuk 35㏊ (18.3%) is growing. Therefore, this study was conducted to introduce the cultivation of plants in the southern highland in Korea. Methods and Results : In order to use this experimental Allium hookeri seedlings were planted in Jeonbuk Sunchang after buying. Allium hookeri cultivation methods put the 3∼4 one eye on the roots. Planting the root length was cut to leave a 3∼5㎝. The planting distance was 40×20㎝. The shielding 35, two months were 50 and 75% by July 1, August 31. The air temperature, soil temperature were investigated in accordance with the changes of light in this experiment. And examined the withering rate, brightness, growth conditions, such as Yield. Conclusion : Test results were as follows. Allium hookeri roots emerged on March 2 during planting 43-68 days. Allium hookeri after shading shoot growth characteristics were as follows. 35% shading and 50% shading was a tendency for the number of leaves increased compared to the non-shading. As a result, flooding was 35% as compared to production per 10a 1,682 ㎏ no light shielding at 50%. Plant analysis leaf mineral contents tended increased nitrogen, phosphate, gallium compared to the non-light cultivation. Mineral contents of the root was nitrogen, potassium is higher in comparison with 75% shading no shading.
        5.
        2014.09 KCI 등재 서비스 종료(열람 제한)
        We analyzed diurnal variations in the surface air temperature using the high density urban climate observation network in Daegu metropolitan city, the representative basin-type city in Korea, in summer, 2013. We used a total of 28 air temperature observation points data(16 thermometers and 12 AWSs). From the distribution of monthly average air temperature, air temperature at the center of Daegu was higher than the suburbs. Also, the days of daily minimum air temperature more than or equal to 25℃ and daily maximum air temperature more than or equal to 35℃ at the schools near the center of Daegu was more than those at other schools. This tendency appeared more clearly on the days of daily minimum air temperature more than or equal to 25℃. Also, the air temperature near the center of the city was higher than that of the suburbs in the early morning. Thus it was indicated that the air temperature was hard to decrease as the bottom of the basin. From these results, the influence of urbanization to the formation of the daily minimum temperature in Daegu was indicated.
        6.
        2007.09 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 여름철 고온현상의 지속기간이 길고 극심했던 1994년과 고온현상 발생일수가 가장 작았던 1993년을 비교하여 서울시의 여름철 고온현상이 사망자 증가에 미치는 영향을 파악하고자 하였다. 여름철 고온현상이 극심했던 1994년 7월의 경우 일별 최고기온과 일별 사망자수 간의 변화 경향이 유사하게 나타났다. 최고기온의 최대값이 나타난 다음날 사망자수의 최대값이 나타났다. 여름철 고온현상이 극심했던 1994년의 경우 일 최고기온과 일별 사망자수 간에 r=0.548의 유의한 상관관계를 나타내었으나 고온현상 발생일수가 작았던 1993년의 경우 유의한 상관관계를 보이지 않았다. 고온현상이 지속되는 동안 사망자의 사망원인을 분석한 결과 내분비ㆍ영양 및 대사 질환으로 인한 사망자수가 43.0%, 순환기계통의 질환으로 인한 사망자수가 30.5%, 호흡기계통 질환으로 인한 사망자수가 43.8% 증가하였다. 여름철 고온현상이 극심했던 1994년은 그 전해에 비하여 65세 이상의 노년층이 다른 연령층에 비하여, 또한 여성이 남성에 비하여 고온에 취약한 것으로 나타났다.