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Asbestos particle dispersion in the atmosphere from abandoned mine sites
이창우,김두영,길세원 한국자원공학회 2012 Geosystem engineering Vol.15 No.2
Asbestos-containing rocks near local abandoned asbestos mines such as serpentine have been exposed to weathering for many years and much concern is being voiced about the risk of asbestos particle dispersion. One of the most serious concerns is asbestos fibers liberated from the various sources generating soil contamination through atmospheric dispersion over an extended area. Thus, this paper aims at predicting the extent and distribution of asbestos soil pollution and defining the target area requiring remediation. Two stages of the study were carried out: (1) a particulate re-entrainment study in the wind tunnel; (2)atmospheric contaminant transport simulation using an Environmental Protection Agency (EPA) atmospheric dispersion model. The planetary boundary layer was created in the wind tunnel to simulate the surface boundary layer from which the settled particulates are re-entrained into the air stream. Since turbulent intensity is known to be the most critical parameter to determine the re-entrainment, it was controlled during the experiments. Also, a series of study have been carried out to see how the moisture content in soil samples affects the re-entrainment. The maximum value of dispersion rate from the sources defined as grams across unit area per unit time was derived for the subsequent atmospheric transport simulation study. ISCST3 (the US EPA’s regulatory model) was applied to predict the short-term as well as long-term transport and settling rate. Meteorological and topographic data at the study site were used for the analysis. The final outcome will be used for determining the target areas for soil treatment.
이창우,김상현,길세원,조우철,Lee, Chang-Woo,Kim, Sang-Hyun,Gil, Se-Won,Cho, Woo-Chul 한국터널지하공간학회 2009 한국터널지하공간학회논문집 Vol.11 No.4
장대터널의 환기 및 방재시스템 설계시 주요한 요소설계인자 중 하나인 자연환기력은 그 중요성에도 불구하고 관련 영향변수들의 상호관계는 정량화가 매우 복잡하여, 자연환기력에 의한 유입 자연풍에 관한 설계기준을 정량적 근거하에서 제시하고 있지 못하다. 최근 발생한 터널화재에 의한 문제 및 터널 이용자에 의한 보다 나은 공기질에 대한 요구 등으로 터널 환기시스템의 최적화가 시급히 필요하며, 따라서 최적화의 주요 설계인자인 자연환기력에 대한 연구가 절실히 요구된다. 본 연구에서는 국내 최장대 도로터널로 계획된 인제터널(연장 10.9 km)을 대상으로 자연환기력의 예측을 목적으로 하였다. 지형적 요인에 의한 외부풍의 풍압에 기인하는 자연환기력의 최대 가능수준을 예측할 수 있는 기압장벽고의 개념을 적용하여 외부풍에 의한 자연환기력을 추정하고 터널내외부 공기 밀도차로 인한 굴뚝효과에 따른 자연환기력을 동시에 분석하였다. One of the key design factors for the ventilation and safety system at extra long tunnel is the airflow velocity induced by the natural ventilation force. Despite of the importance, it has not been widely studied due to the complicated influencing variables and the relationship among them is difficult to quantify. At this moment none of the countries in the world defines its specific value on verified ground. It is also the case in Korea. The recent worldwide disasters by tunnel fires and demands for better air quality inside tunnel by users require the optimization of the tunnel ventilation system. This indicates why the natural ventilation force is necessary to be thoroughly studied. This paper aims at predicting the natural ventilation force at a 11 km-long tunnel which is in the stage of detailed design and will be the longest vehicle tunnel in Korea. The concept of barometric barrier which can provide the maximum possible natural ventilation force generated by the topographic effect on the external wind is applied to estimate the effect of wind pressure and the chimney effect caused by the in and outside temperature difference is also analyzed.
파어탕의 L-NAME 유도 고혈압 동물군에서의 혈압강하효과 및 심신기능 개선 효과
나세원,홍미현,김혜윰,장윤재,윤정주,이윤정,강대길,이호섭,Na, Se Won,Hong, Mi Hyeon,Kim, Hye Yoom,Jang, Youn Jae,Yoon, Jung Joo,Lee, Yun Jung,Kang, Dae Gill,Lee, Ho Sub 대한한의학방제학회 2020 大韓韓醫學方劑學會誌 Vol.28 No.3
Hypertension has been approved to cause disharmony between the heart and kidney such as cardiac hypertrophy and kidney dysfunction. In traditional oriental medicine Paeo-tang (PET) has been shown to have effects on blood circulation improvement. However, the beneficial effect of PET on hypertension remains unknown. In this study, we investigated that PET attenuates blood pressure and improves cardiovascular and renal function in NG-nitro-L-arginine methylester (L-NAME) rat model. Hypertensive rat models were induced by the administration of L-NAME (40 mg/kg/day) and then PET (50 or 100 mg/kg/day) or Olmetec was treated for 2 weeks. PET treatment significantly suppressed the systolic blood pressure and decreased intima-media thickness in the thoracic aorta. PET ameliorated endothelium-dependent and independent vascular relaxation in the L-NAME-induced vascular dysfunction. PET ameliorated the functional decline in the kidney such as albumin and blood urea nitrogen in plasma. These results demonstrated that PET possesses protective effects against L-NAME-induced hypertension.
In-situ Vacuum Hot Press 공정을 이용한 SiCp/Al 복합재료의 제조
최세원,홍성길,김영만,장시영,강창석,Choe, Se-Won,Hong, Seong-Gil,Kim, Yeong-Man,Jang, Si-Yeong,Gang, Chang-Seok 한국재료학회 2001 한국재료학회지 Vol.11 No.7
본 연구에서는 특별하게 고안된 In-situ VHP 제조 공정을 이용하여 상온에서 $500^{\circ}C$까지의 진공 열간 압축과 canning 작업 없이 $520^{\circ}C$에서 연속 압출옳 하여 Sicp/pure Al과 SiCp/2024Al MMCs를 제조하였다. 복합재료의 인장강도와 미세구조에 영향을 주는 SiC 입자크기, 체적률, 압출비에 대해서 조사하였다. 압출비 10:1의 경우에는 SiCp/pure Al과 SiCp/2024Al 복합재료 둘 다 건전한 외형과 SiCp의 일정한 분산을 가지면서 SiCp의 균열이 없는 좋은 미세 구조를 가지고 있었다. 그러나 압출비 16:1의 경우에는 체적률이 증가할수록 파괴된 SiC 입자의 수가 증가하였으며 2024Al 기지내의 복합재료와 순수한 Al 기지재 복합재료를 서로 비교하였다. 동일한 체적률과 압출비의 경우에는 SiCp의 크기가 작은 복합재료가 SiCp가 큰 복합재료보다 인장강도가 더 높았다. SiCp/pure Al and SiCp/2024Al MMCs were fabricated by in-situ VHP process designed specially just in this study which is composed of the vacuum hot press at range from R.T. to $500^{\circ}C$ and the continuous extrusion without canning process at $520^{\circ}C$. It was investigated the effect of SiC particle size, volume fraction and extrusion ratio on the tensile properties and micro structure in auf composites. In case of the 10:1 extrusion ratio, but SiCp/pure Al and SiCp/2024Al composites were shown a sound appearance and a good micro structure without crack of SiCp as well as uniform distribution of SiCp. However, in case of the 16:1 extrusion ratio, the number of cracked SiC particles more than increased in a higher volume fraction composite and 2024Al matrix composite compared with pure Al matrix one. The tensile strength of the composites reinforced smaller SiCp was higher than that of the bigger SiCp reinforced in same volume fraction and extrusion ratio.
Al-Mg계 합금과 Al-Si계 합금의 다이캐스팅 응고과정의 차이
최세원,김영찬,조재익,강창석,홍성길,Choi, Se-Weon,Kim, Young-Chan,Cho, Jae-Ik,Kang, Chang-Seog,Hong, Sung-Kil 한국재료학회 2012 한국재료학회지 Vol.22 No.2
The effect of the alloy systems Al-Mg alloy and Al-Si alloy in this study on the characteristics of die-casting were investigated using solidification simulation software (MAGMAsoft). Generally, it is well known that the casting characteristics of Al-Mg based alloys, such as the fluidity, feedability and die soldering behaviors, are inferior to those of Al-Si based alloys. However, the simulation results of this study showed that the filling pattern behaviors of both the Al-Mg and Al-Si alloys were found to be very similar, whereas the Al-Mg alloy had higher residual stress and greater distortion as generated due to solidification with a larger amount of volumetric shrinkage compared to the Al-Si alloy. The Al-Mg alloy exhibited very high relative numbers of stress-concentrated regions, especially near the rib areas. Owing to the residual stress and distortion, defects were evident in the Al-Mg alloy in the areas predicted by the simulation. However, there were no visible defects observed in the Al-Si alloy. This suggests that an adequate die temperature and casting process optimization are necessary to control and minimize defects when die casting the Al-Mg alloy. A Tatur test was conducted to observe the shrinkage characteristics of the aluminum alloys. The result showed that hot tearing or hot cracking occurred during the solidification of the Al-Mg alloy due to the large amount of shrinkage.
Al 합금과 STD61강의 소착에 미치는 첨가원소 Fe, Mn의 영향
김유미,홍성길,최세원,김영찬,강창석,Kim, Yu-Mi,Hong, Sung-Kil,Choi, Se-Weon,Kim, Young-Chan,Kang, Chang-Seog 한국재료학회 2012 한국재료학회지 Vol.22 No.4
Recently, various attempts to produce a heat sink made of Al 6xxx alloys have been carried out using die-casting. In order to apply die-casting, the Al alloys should be verified for die-soldering ability with die steel. It is generally well known that both Fe and Mn contents have effects on decreasing die soldering, especially with aluminum alloys containing substantial amounts of Si. However, die soldering has not been widely studied for the low Si aluminum (1.0~2.0wt%) alloys. Therefore, in this study, an investigation was performed to consider how the soldering phenomena were affected by Fe and Mn contents in low Si aluminum alloys. Each aluminum alloy was melted and held at $680^{\circ}C$. Then, STD61 substrate was dipped for 2 hr in the melt. The specimens, which were air cooled, were observed using a scanning electron microscope and were line analyzed by an electron probe micro analyzer. The SEM results of the dipping soldering test showed an Al-Fe inter-metallic layer in the microstructure. With increasing Fe content up to 0.35%, the Al-Fe inter-metallic layer became thicker. In Al-1.0%Si alloy, the additional content of Mn also increased the thickness of the inter-metallic layer compared to that in the alloy without Mn. In addition, EPMA analysis showed that Al-Fe inter-metallic compounds such as $Al_2Fe$, $Al_3Fe$, and $Al_5Fe_2$ formed in the die soldering layers.