• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1040-1045
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• 2004

This study has been carried out to investigate thermosyphon's geyser boiling phenomenon used to solar collector. evaporator section of thermosyphon used to solar collector is very much longer than that of condenser section. From the results from this study, Geyser boiling's cycle depends on cooling water, tilt angle and the applied heat load at the evaporator. In this study, according to heat load, the geyser boiling frequency is lower, but the amplitude higher. For the high tilt angle of heat pipe, the frequency and amplitude are lower and higher in the evaporator region, respectively. Whereas, these phenomena is in contrast in the condenser region.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.174-174
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• 2015

국내의 국지성 집중호우와 같은 기후변화와 토지피복율 증가 등 복합적인 원인으로 인한 표면 유출수의 증가로 도시에서의 내수침수가 매년 빈번하게 발생하고 있다. 이러한 도심지 돌발홍수로 인한 피해에 대한 구조적인 대책으로 지하방수로가 효과적인 방안으로 대두되고 있으며, 현재 신월빗물저류배수시설이 설계단계에 있다. 그러나 미국, 일본 등의 국외의 기설치된 지하방수로에서 발생되는 Geyser 현상으로 인한 피해에 대한 연구는 국외에 비해 미비한 편이므로, 선행적으로 Geyser에 대한 물리기반의 동수역학적인 이해가 필요한 실정이다. Geyser는 홍수 시 급격한 유량의 유입으로 단파가 발생하여 지하방수로 내 공기의 압축이 발생하고 수직관을 통해 공기가 물과 함께 지상으로 분출되면서 발생된다. 따라서 공기와 물의 혼합 유동을 모의해야 하며 동시에 단파의 불연속성을 모의하기 위해서는 기존의 상용프로그램으로는 다소 어려움이 있다. 이에 본 연구에서는 지하방수로의 Geyser 현상의 발생 예측을 위해 1차원 Saint-Venant 방정식을 지배방정식으로 선정하였으며, 단파 발생을 수치적으로 안정적으로 모의하기 위해 Roe Approximate Riemann 수치기법을 사용하였다. 또한 공기의 압력항을 고려하기 위해서 수정된 형태의 Preissmann slot 모형을 적용하였다. Geyser 현상의 영향인자로서 지하방수로 수평관의 직경, 마찰계수, 바닥경사, 초기수위, 유입유량을 고려하였으며 상류에서 유입되는 유량에 의한 하류에서의 동수역학적 거동을 분석하였다. 5개의 영향인자의 변화에 따른 단파의 유입속도 및 공기부 압력의 변화를 관찰하여 Geyser 현상에 대한 동수역학적 검토를 수행하였다. 추후 본 연구결과를 적절히 활용한다면 지하방수로의 사용 안정성을 확보하고, 홍수발생 시 모니터링 인자도출에 도움이 될 것으로 예상된다.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1851-1859
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• 2022

Experimental research on flow characteristics of open natural circulation system was performed, to figure out the mechanism of the open natural circulation behaviors. The influence factors, such as the heating power, the inlet subcooled and the level of cooling tank on the flow characteristics of the system were examined. It was shown that within the scope of the experimental conditions, there are five flow types: single-phase stable flow, flash and geyser coexisting unstable flow, flash stable flow, flash unstable flow, and flash and boiling coexisting unstable flow. The geyser flow in flash and geyser coexisting unstable flow is different from classic geysers flow. The flow oscillation period and amplitude of the former are more regular, is a newly discovered flow pattern. By drawing the flow instability boundary diagram and sorting out the flow types, it is found that the two-phase unstable flow is mainly characterized by boiling and flash, which determine the behavior of open natural circulation respectively or jointly. Moreover, compared with full liquid level system, non-full liquid level system is more prone to boiling phenomenon, and the range of heat flux density and undercooling degree corresponding to unstable flow is larger.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2001.03a
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• pp.70-71
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• 2001

• Communications for Statistical Applications and Methods
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• v.8 no.1
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• pp.117-126
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• 2001

We provide a simple chi-squared test of multivariate normality based on rectangular cells on the spherical data. This test is simple since it is a direct extension of the univariate chi-squared test to multivariate case and the expected cell counts are easily computed. We derive the limiting distribution of the chi-squared statistic via the conditional limit theorems. We study the accuracy in finite samples of the limiting distribution and then compare the poser of our test with those of other popular tests in an application to a real data.

• Journal of environmental and Sanitary engineering
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• v.21 no.3 s.61
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• pp.9-14
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• 2006

From March 1, 2005 to August 31, 2006 mineral water wells were selected for 13 areas in Southeast Asia (Indonesia, Philippines, Thailand, Singapore) and 20 areas in Northeast Asia (Korea, North Korea, China, Japan) and the study on their mineral water quality was analyzed. - Mineral water quality was the best in Korea. Mineral spring waters in some area of China and North Korea and in the whole area of the Southeast Asia were of poor quality. - The hardness of mineral water was the low in Korea $(10{\sim}47mg/L\;as\;CaCO_3)$, Japan $(4{\sim}66mg/L\;as\; CaCO_3)$, Geumgang-san North Korea Area $(4mg/L\;as\;CaCO_3)$. Mineral spring water in Thailand, Indonesia $(1{\sim}97.5mg/L\;as\;CaCO_3)$ and in the other area $(120{\sim}1205mg/L\;as\;CaCO_3)$ were high degree of hardness. - pH value in the mineral water of Southeast Asia $(pH\;6.7{\sim}8.2)$ and Northeast Asia $(pH\;5.9{\sim}7.9)$ was up to WHO standard $(pH\;6.5{\sim}8.5)$. Fluorine of negative ion was found in 10 mineral waters: Indonesian mineral water 'ATARTN'(0.02mg/L), Thailand mineral water 'SIAM' (0.6mg/L), 'MASAFI' (0.02mg/L). Korean mineral water 'SAEMMULNARA' (1.1mg/L), 'SANSU'(0.6mg/L), 'ICIS'(0.3mg/L), 'DONGWON SAEM-MUL'(0.03mg/L), 'PYEONGCHANG' (0.6mg/L), North Korean mineral water 'KUMGANGSAN'(0.1mg/L), Japanese mineral water 'CRYSTAL GEYSER'(0.55mg/L). However Fluorine in the other 23 mineral waters were not detectable.

• Journal of the Speleological Society of Korea
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• no.68
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• pp.5-22
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• 2005

Since earlier in 1947 the writer had been devoting part of his time to study alluvial fans in Korea based on his own interest in geomorphology. However, it was in 1958 when a new geography department was set up and the Research Center of National Lands was established in the university of Kyung Hee, the writer started scientific investigation for alluvial fans. The Following alluvial fans have been studied by the writer: those of Mt. Kwanak and Mt. Chungge in 1947; those of Pulkuksa in 1948; those of Suhnamsa, Suh Myun, Pusan in 1950; those of Shindonae, Mt. Kerrong, in summer of 1958; those of Hwaomsa, Kure and Yongsan Myun, Changhung, in winter of 1958. The article is the comparative study of the above mentioned alluvial fans including Suhkwangsa Fan, Chugaryng Rift Valley. Of course this is not the study covering all af alluvial fans in Korea. Within the limits of his surbey, the writer has com to a conclusion which may be helpful for the Korean alluvial fm study. 1. Korean alluvial fans are generally found in rift valleys or basins. 2. They are formed in places of below 220-meter contour line. 3. The slope from fna apex to river valley is 20-40 degree. The slope of fan surface is 5-20 degree, but most of them under 16 degree. A sudden change of slope is taken place or the fan apex and fan center. 4. Hills (100-200m) are developed on the surfaces of alluvial fans. 5. Most of rivers in alluvial fans are geyser rivers. 6. The depth of well : from ground surface to the well water surface is 4-8 m; water depth is 1-2m. 7. Land utilization; cultivated land 30%: non cultivatedland 70%. The area occupied by upland fields is twice of paddy field area. 8. Settlement : agglomerated settlement is developed on the top or the end of fan and surrounded by windbreakers. 9. Farming pattern at the top of fan fields are rectangular and parallel to flumes but at the center of fan, they are irregular and perpendicular to flumes.

• Economic and Environmental Geology
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• v.46 no.3
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• pp.267-278
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• 2013

The East African Rift System(EARS) is known to be hosted epithermal Au-Ag deposits, and the best-known example is Main Ethiopian Rift Valley(MER) related to Quaternary bimodal volcanism. Large horst-graben system during rifting provides open space for emplacement of bimodal magmas and flow channel of geothermal fluids. In recent, large hydrothermally altered zones(Shala, Langano, and Allalobeda) and hot spring related to deeply circulating geothermal water have been increasing their importance due to new discoveries in MER and Danakil depression. The hot springs in Shala and Allalobeda occur as boiling pool and geyser on the surface, whereas some areas didn't observe them due to decreasing ground water table. The host rocks are altered to quartz, kaolinite, illite, smectite, and chlorite due to interaction with rising geothermal water. The hot springs in MER are neutral to slightly alkaline pH(7.88~8.83) and mostly classified into $HCO_3{^-}$ type geothermal water. They are strongly depleted in Au, and Ag, but show a higher Se concentration of up to 26.7 ppm. In contrast, siliceous altered rocks around hot springs are strongly enriched in Pb(up to 33 ppm, Shala), Zn(up to 313 ppm, Shala), Cu(up to 53.1 ppm, Demaegona), and Mn(up to 0.18 wt%t, Shala). In conclusion, anomalous Se in hot spring water, Pb, Zn, Cu, and Mn in siliceous altered rocks, and new discoveries in MER have been increasing potential for epithermal gold mineralization.

• Journal of The Geomorphological Association of Korea
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• v.20 no.4
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• pp.15-28
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• 2013

This paper was made on the basis of geotourism to explain morphological characteristics of Patagonia and Atacama region in the Andes through 10-day fieldwork. The Patagonian landscape was focused on the Torres del Paine National Park, Chile and the Los Glacier National Park, Argentina; on the other hand, the Atacama morphological landscape was investigated around the San Pedro de Atacama. Many geomorphological features such as uplift, semiarid and glacier landscapes can be found in Patagonia, so it is strongly recommended to have an opportunity to enjoy these landforms by geotourism. Massive intrusive rock bodies of granite can be shown in those two National Parks declared a Biosphere Reserve by UNESCO. And, the Atacama Desert located on the forearc depression in the Andes, Chile has also many geomorphological destinations of arid and volcanic landforms; badland, pediplain, pediment, salt lake and geyser. Especially, huge pediplain is one of the greatest view points in the Atacama Desert. Patagonia and Atacama are the best geographical tourism sites to know diverse tectonic landforms made by the conflict between South American and Pacific plates.