• Journal of the Mineralogical Society of Korea
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• v.25 no.2
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• pp.63-76
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• 2012

Tachylite, black basaltic glass formed by the rapid cooling of molten basalt, locally occurs at the Basaltic Agglomerate Formation (BAF), the lowest formation of Ulleung Island. The purposes of this study are to characterize the occurrence and mineralogy of tachylite and to elucidate its formation condition, with emphasis on its fracture pattern, which can serve as implications for the early volcanic activity of Ulleung Island. To this end, we investigated the occurrence pattern of tachylite in the field and carried out mineralogical analyses using optical microscope, XRD, EPMA, and SEM. Tachylite occurs at the chilled margin of basic dikes which are distributed in Naesujeon, Dodong and Jeodong seasides, Turtle Rock, and Yaerimwon, whose widths vary from several cm to 10 cm. It is evident that the outer surface of tachylite is dense and smooth, whereas the inner surface, if fractured, is characterized by conchoidal fracture. The matrix of tachylite consists of amorphous, glass and some fine-grained phenocrysts present in tachylite include biotite, anorthoclase, sanidine, plagioclase, hornblende, and Fe-Ti oxides. The fracture patterns characteristic of tachylite are subrounded, oval, or less commonly polygonal, bounded by joints to form globule or lump. Taking into account texture and mineralogy, tachylite is interpreted to have undergone little subsequent alteration at low temperature via hydration or hydrolysis that could form clay minerals after it was formed. Because tachylite with peculiar fractures occurs as dikes in a close association with BAF, its presence is considered as reliable evidence that when tachylite formed, the most part of BAF was still under subaqueous conditions, or at least saturated with seawater.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.5
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• pp.53-68
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• 1996

마그네슘이 자동차 경량화에 관심이 되는 이유는 근본적으로 CAFE 규제와 같이 경량화를 통한 화석연료의 소모를 크게 억제해야 한다는 사회적인 규제이나, 지난 10여년간의 기술발전으로 내식성이 나쁘다거나 취급이 위험한 금속이라는 인식이 크게 개선된 데에도 있다. 다른 경량금속에 대한 Mg 지금 가격의 비교조건이 호전되었고 향후 원소 재공급의 다변화가 추진되고 있는 것도 환경을 변화시킨 중요한 요인이다. 그간 중요한 경량화 대체 재료로 연구투자가 많았던 유기고분자 재료 및 FRP 등과 같은 복합재료는 폐기부품의 재활용이 어려움 때문에 호나경친화적인 단점이 부각되어, 이 소재의 증가가 주춤해 있다. 마그네슘의 경우에는 재활용이 가능하고, 진동흡수효과가 매우 커서 소음발생을 크게 줄일 뿐만 아니라, 주행 및 내구성시험에서 치수안정성이 좋고 많은 종류의 전자기기 사용에 의한 전자파 차폐효과도 큰 장점을 가지고 있다. 본 고에서는 Mg 다이캐스팅으로 자동차부품의 경량화 현황과 선진국에서 보는 전망을 미국을 중심으로 정리하고, 이와 관련한 Mg 다이캐스팅으로 자동차부품의 경량화 현황과 선진국에서 보는 전망을 미국을 중심으로 정리하고, 이와 관련한 Mg 기술적인 이슈와 시장전망도 서술하였다. 그리고 현재 우리나라의 연구계와 부품업계에서 추진하고 있는 연구개발 동향을 자동차 업계에 소개하는 의미도 있다. 이처럼 우리나라의 현황을 정리해 보는 것은 국내 자동차 산업이 국제적인 경쟁을 하고 있고 Mg기술과 원료확보에서 일본의 견제를 받고 있는 우리의 현실에서도 필요한 작업으로 생각된다.값들로 구성되는 형상을 내구 성능, 성형성등을 고려하여 최종 형상으로 결정한다. 내구성능의 예측은 금속부품의 내구수명 예측에 널리 이용되고 있는 방법이 방진 고무부품의 경우에도 적용 가능한지를 검토하고, 방진 고무부품에도 일반적으로 적용될수 있는 내구수명 예측방안의 개발 가능성을 타진해 보았다. 본 연구의 목표는 시제품을 제작하기 이전에 설계된 부품에 대한 스프링 상수 및 내구특성을 체계적으로 규명하여 제품 시험의 횟수를 줄이고, 보다 정밀한 제품을 제작할 수 있도록 하기 위한 것이다.세포수는 초기 배반포기배에서 팽윤 배반포기배로 진행됨에 따라 두배에서 세배 정도 증가되었음을 알 수 있었다. 또한, differential labelling과 bisbenzimide기법에서 얻어진 각각의 총세포수를 비교하였을 때 총세포수는 발달의 진행 정도에 따라 증가되며 그와 동시에 동일한 군 간의 세포수도 거의 유사함을 알 수 있었다. 따라서, ICM과 TE를 differential labelling하는 기법은 수정란의 quality를 평가하는데 매우 유용한 기법으로서 착상전 embryo 발달을 연구하는데 효과적으로 이용될 수 있다는 것을 시사한다. 고도의 유의차를 나타낸 반면 비수구, 초생수로구 및 Bromegrass 목초구 간에는 아무런 유의차가 인정되지 않았다. 7. 농지보전 처리구인 배수구와 초생수로구는 비처리구에 비해 낮은 침두 유출량과 낮은 토양유실량을 나타내었다.구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at%

• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.132-135
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• 1998

This study was conducted to obtain basic information for soil improvement in flower crop cultivating greenhouse soil through survey on the chemical and physical properties of greenhouse soils. Total of 85 Flowcultivating farms were surveyed and analysis was done on the soil characteristics, amounts of chemical fertilizer and soil amendmentuse. The result are as follows: In soil properties of flower cultivating greenhousees, silt clay loam was 51%and 68% of the surveyed soils had good drainage condition. Ground water table was over 90-120cm which was optimum range for flower cultivation. Flower cultivating farms had problem with accumulation of fertility. Nitrate nitrogen was accumulated in Gypsophila paniculate farms and available phosphorus, and exchangeable postassium were significantly higher in greenhouse soils about 2 times than in open field soil. Application amount of chemical feltilizers in greenhouses were nitrate 211,phosphorus 135, and potassium 132kg/ha, respectively. Amount of organic matter used in greenhouse were high in order of cattle manure> compost> organic fertilizer> poultry manure> swine manure and their application amounts were69, 103, 32, 20, and 43 MT/ha, respectively.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.50-54
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• 2012

$Salmonella$ spp. and $Brucella$ spp. have caused a considerable disease of farmed animals and economic loss in animal farming and food industry. In this study, the disinfection efficacy of Vital-$Oxidel^{(R)}$, a commercial disinfectant, composed to chlorine dioxide, betaine hydrochloride, and propylene glycol was evaluated against $S.$ $typhimurium$ and $Brucella$ $ovis$. A bactericidal efficacy test by broth dilution method was used to determine the lowest effective dilution of the disinfectant following exposure to test bacteria for 30 min at $4^{\circ}C$. Vital-$Oixdel^{(R)}$ and test bacteria were diluted with distilled water (DW), hard water (HW) or organic matter suspension (OM) according to treatment condition. On OM condition, the bactericidal activity of Vital-$Oixdel^{(R)}$ against S. typhimurium and Brucella ovis was lowered compared to that on HW condition. As Vital-$Oxidel^{(R)}$ possesses bactericidal efficacy against animal pathogenic bacteria such as $S.$ $typhimurium$ and $Brucella$ $ovis$, this disinfectant solution can be used to control the spread of bacterial diseases.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.260-270
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• 1998

The field tests were performed to suggest the rational method for stability evaluation of soft clay. The behavior of settlement-displacement obtained by field monitoring system was to compare and analyze the results of the observationed method, and to investigate the complex behavior of soft clay with filling height. The results of this study are summarized as follows. 1. The horizontal displacement was suddenly increased when physical properties of soft clay showed maximum values and the part of the turning point. The values of these properties were available to the fundamental data for stability evaluation. The shear deformation appeared that difference of the horizontal displacement was maximum values. 2. Although the stability of embankment by step filling showed the unstable part over the failure standard line, the embankment was confirmed stable. So the evaluation of the stability of embankment is reasonable to use the inclination of curve than failure standard line. 3. The horizontal displacement and relative settlement were increased as same ratio at improvement ground. Estimation of shear deformation using Terzaghi's modified bearing capacity should consider the relations of embankment load and undrained shear strength at nonimprovement ground, and minimum safety factor is recommended to use larger than 1.2. 4. Excess pore water pressure was increased with increasing of filling height and decreased with maintain the filling height. The embankment was unstable when filling height was exceed the evaluation standard line, and the behavior of excess pore water pressure and horizontal displacement could use as a standard of judgement of the filling velocity control because their behavior were agree with each other.

• Journal of the Korean Geosynthetics Society
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• v.6 no.1
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• pp.9-16
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• 2007

Geotextile is one of the most useful and effective polymer material in civil construction works and the main function of geotextile is separation, reinforcement, filtering and drainage. Recently, because of the shortage of natural rock, traditional forms of river and coastal structures have become very expensive to build and maintain. Therefore, the materials used in hydraulic and coastal structures are changing from the traditional rubble and concrete systems to the cheaper materials and systems. One of these alternatives employs geotextile tube technology in the construction of coastal and shore protection structures, such as embankment, see dyke, groins, jetties, detached breakwaters and so on. Geotextile tube technology has changed from being an alternative construction technique and, in fact, has advanced to become the most effective solution of choice. This paper presents case history of sea dyke filter construction using geotextile tube mattress and also, various issues related to the tube mattress design and construction technology.

• Korean Journal of Plant Taxonomy
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• v.38 no.4
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• pp.583-599
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• 2008

Dokdo, small island located in the eastern end of the Korean Peninsula, has been an uninhabited island for long time due to long distance from the land. Moreover, the steep slope of volcanic tuff at Dokdo is well drained for high permeability and Dokdo has few plain areas, swamps and very thin soil layers. In this study, pollen analysis at Dokdo was attempted on the profile of organic sandy soil for the first time in Korea owing to the marine climate environment with high humidity and precipitation including snowfalls in spite of unprofitable condition geologically or geomorphologically. While many historical, political researches have been accumulated for territorial problem of Dokdo with Japan, natural scientific researches with field work are not sufficient, and few paleoecological researches have been done. As a result of pollen analysis, the ratio of the NAP(Non-Arboreal Pollen) and spore was higher than AP(Arboreal Pollen), and the vegetation change existed by showing dramatic decrease of AP at the upper layer. AP was composed of almost Pinus, and a little Alnus, Quercus, Betula, Carpinus, Picea and Ulmus. NAP was composed of Gramineae, Compositae, Chenopodiaceae Cyperaceae, Caryophyllaceae, Liliaceae, Umbelliferae, Artemisia, Lobelia, Rumex, Polygonum. Increase of the NAP such as Gramineae, Artemisia and Chenopodiaceae, they would mostly have been transported from the other areas because agricultural activity is impossible at Dokdo. While one reason of Pinus thunbergii decrease could be regarded as environmental change, the other reason would be lumbering of pine trees by human activity which is adapted to Dokdo environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1887-1891
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• 2010

전자파표면유속계를 이용한 홍수유속측정에 있어서 수심평균유속환산계수로 0.85를 표면유속에 일률적으로 적용하도록 제시하고 있다. 그 동안 이의 적절성 여부에 대한 논의가 꾸준히 지속되어져 왔다. 이에 전자파 표면유속계를 개발하고 상품화하여 보급시킨 개발 주체의 입장에서 이에 대한 검증을 시도하였다. 이의 검증을 위해서 가장 중요한 것은 정해진 측정지점의 유량측정시각의 정확한 유량을 파악해야 함은 필수조건이다. 하지만 유량측정지점의 유량의 참값은 알기는 참으로 어려운 일이다. 이에 지금까지는 댐의 방류량을 참값이라고 가정을 하고 여러 가지 기기를 이용한 유량측정을 실시하여 각 기기의 측정오차를 비교하는 기준유량으로 댐방류량을 이용하였다. 따라서 본 연구에서는 방류량의 정확성 파악에 의하여 수심평균유속환산계수의 적정성 여부를 검토하고자 하였다. 또한 이에 대한 이론적인 접근의 방법으로서 유속분포곡선식으로부터 수심평균유속환산계수를 산정하여 이를 기존에 표면유속을 평균유속으로 환산하기 위해서 적용하였던 계수와 비교를 하였다. 기존의 수심평균유속환산계수로 이용한 0.85에 대한 이론적인 검증을 위해서 Power law형의 유속분포식으로부터 수심평균유속환산계수를 유도한 결과 하상의 재료에 따라 0.833 (거친 하상)~0.875 (부드러운 하상)의 범위에 분포하였다. 이는 환산계수로 이용하고 있는 0.85는 유속분포가 크게 변동하지 않은 경우에 수심 평균유속을 환산하는데 이용함에 무리가 없음을 보여준다. 기존의 대청댐 방류량을 이용한 수심평균유속환산 계수를 산정한 결과를 분석한 결과 환산계수가 0.828~0.868의 범위에 분포하고 있다. 즉 기존의 수심평균유속환산계수로 이용을 하고 있는 0.85와 비교했을때 ${\pm}3%$의 오차를 보이고 있음을 알 수 있다. 대청댐 방류량에 대한 검증을 위해서 여러 가지 기기를 이용한 동시 유량 측정을 실시하였고, 전자파표면유속계로 측정한 표면유속에 기존의 수심평균유속환산계수 0.85를 적용했을때의 유량산정 결과를 다른 방법에 의한 측정 결과 및 방류량과 비교를 실시하였다. ADCP 측정은 유량조사사업단과 한국수자원공사 충청지역본부의 도움을 받아 실시하였는데, 유량조사사업단은 9회 측정하여 평균한 유량이 242.0 cms, 충청지역본부에서는 6회 측정하여 평균한 결과가 234.6 cms이었고, 전자파표면유속계로 측정한 표면유속을 이용하여 산정한 유량이 249.0 cms이었으며, 동시유량 측정당시 방류량은 242 cms이었다. ADCP를 이용한 유량측정에 있어서, 각 측정시의 유량측정 오차가 최대 20% 까지 나타나고 있다. 반면 대청댐의 발전 방류량은 거의 일정한 수준을 유지했던 것을 감안할 경우 유량측정 기간에 하류의 조정지댐으로 인한 배수효과의 영향으로 ADCP를 이용한 유량측정값에 변동이 발생한 것으로 추측된다. 전반적으로 부자를 제외하고는 사용된 유량측정 방법들이 거의 동일한 값을 보임을 알 수 있다. 또한 표면유속에 기존의 환산계수를 적용하여도 유량산정이 다른 방법과 유사하게 산정됨을 알 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.198-208
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• 2011

When a structure which has relatively low load constructs on soft clay, the bearing capacity of the ground will be improved by sand overlying clay. In this condition, verifying the bearing capacity is difficult from the P.B.T etcetera in the in-situ. So, it is needed to estimate precise bearing capacity in the design process. In this study, 2-dimensional chamber tests and FEM analyses are conducted to evaluate behavior of bearing capacity for shallow foundations on a sand overlying clay. Because depth ratio H/B and bearing capacity ratio $q_c/q_s$ are selected as main factors, height of a sand, undrained shear strength of a clay and width of a loading are designated as variables. Results from chamber tests are very similar with those of FEM analyses. And it shows that punching shear mechanism is more suitable than the equation of Okamura et al.(1998). To make continual application of load spread mechanism, the equivalent load spread angle is proposed for H/B and $q_c/q_s$. Also, the linear regression equation of critical depth ratio Hf is suggested for $q_c/q_s$.

• Journal of the Korean Geosynthetics Society
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• v.5 no.4
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• pp.11-18
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• 2006

Geotextile has been used for various types of containers, such as small hand-filled sandbags, 3-dimensional fabric forms for concrete paste, large soil and aggregate filled geotextile gabion, prefabricated hydraulically filled containers. They are hydraulically filled with dredged materials and have been applied in coastal protection and scour protection, dewatering method of slurry, temporary working platform for bridge construction, temporary embankment for spill way dam construction. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. The paper presents the stability behavior of geotextile tube composite structure by 2-D limit equilibrium and slope stability analysis. 2-D limit equilibrium analysis was performed to evaluate the stability of geotextile tube composite structure to the lateral earth pressure and also transient seepage and stability analysis were conducted to determine the pore pressure distribution by tide variation and slope stability. Based on the results of this paper, the three types of geotextile tube composite structure is stable and also slope stability of overall geotextile tube composite structures is stable with the variation of tidal conditions.