• Journal of the Korean earth science society
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• v.37 no.1
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• pp.62-77
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• 2016

In the early model of plate tectonics, the plate was depicted as a passive raft floating on the convecting mantle and carried away by the mantle flow. At the same time, ridge push at spreading boundaries and drag force exerted by the mantle on the base of lithosphere were described as the dominant driving forces of plate movements. However, in recent studies of plate tectonics, it is generally accepted that the primary force driving plate motion is slab pull beneath subduction zones rather than other forces driven by mantle convection. The current view asserts that the density contrast between dense oceanic lithosphere and underlying asthenosphere is the substance of slab pull. The greater density of oceanic slab allows it to sink deeper into mantle at trenches by gravitational pull, which provides a dominant driving force for plate motion. Based on this plate tectonics development, this study investigated the contents of plate tectonics in high school Earth Science textbooks and how they have been depicted for the last few decades. Results showed that the early explanation of plate movement driven by mantle convection has been consistently highlighted in almost all high school textbooks since the 5th curriculum, whereas most introductory college textbooks rectified the early theory of plate movement and introduced a newly accepted theory in revised edition. Therefore, we suggest that the latest theory of plate tectonics be included in high school textbooks so that students get updated with recent understanding of it in a timely manner.

• Journal of Preventive Medicine and Public Health
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• v.31 no.2 s.61
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• pp.249-264
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• 1998

Reports on a potential relationship between sensory neural hearing loss(SNHL) and cardiovascular or hematologic factor show that the results are controversial. A detailed analysis of risk factors in the development of SNHL was carried out in 3,050 non-noise exposed healthy worker. The mean hearing threshold of both ears at 500, 1000, 2000, 4000, 8000Hz was measured and the effect of age, possible cardiovascular risk factor and hematologic factor (blood viscosity and hemostatic factors) on SNHL were evaluated. first, each of these were associated with loss of hearing sensitivity when univariately and multivariatively analysed. In a multiple regression model, age, sex, body mass index, WBC and total cholesterol level were independently associated with the mean of hearing sensitivity decrease at 4000 and 8000Hz. Second, study subjects were divided into two group (normal vs SNHL) and we compare the possible risk between both groups, and analysed univariate and multivariative logistic model. In a multiple logistic regression model, age, sex, body mass index, WBC and total cholesterol level, total protein, platelet were independently associated with SNHL. Our results show that we have some reliable indices of susceptibility to SNHL using cardiovascular measures or biochemical factor, but future, more extensive studies are required.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.253-253
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• 2019

유사의 이동은 하천, 해안 지역과 같은 수계에서 하상의 변동, 침식과 퇴적을 일으켜 지형적인 변화를 초래한다. 유사의 이동은 유사의 특성과 유체의 유수동역학적 특성에 의해 결정되며 유체특성 간의 복잡한 상호 작용에 의해 변화한다. 유사가 가지는 점착성은 유사의 특성에 큰 영향을 끼친다. 입자의 크기가 매우 작은 점착성 유사는 그 표면이 가지는 전자기적 점착력에 의해 주위의 1차 입자나 다른 작은 알갱이들이 서로 뭉치는 응집과 충돌에 의해 크기가 작아지는 파괴의 과정을 겪는다. 이 과정을 응집현상이라고 하며 응집현상을 통해 점착성 유사의 크기와 밀도, 침강속도는 계속해서 변화한다. 따라서 점착성 유사의 응집거동 고려한 유사 이동 연구는 필수적이다. 과거 연구의 많은 사례에서 유사의 크기와 농도는 비례 관계를 가지는 것이 일반적이라 알려져 있다. 그러나 실제 현장에서 측정한 결과 유사의 크기와 농도가 반비례 관계를 가지는 특이점이 발견되었다. 실측 연구에서 발견된 응집거동에 따른 유사의 특성의 특이한 변화를 설명하기 위해 1차원 연직 수치 모형(1DV)을 이용하여 수치 실험을 수행하였다. 모의 수행 시, 흐름 조건을 크기와 방향이 일정한 순방향흐름(Current)에 특정 주기와 진폭을 가지는 진동 흐름(Oscillatory Flow)을 추가하여 진행하였다. 플럭의 성장과 그에 따른 입자의 크기는 많은 현상에 영향을 받는다. 그 중 응집현상의 응집 과정과 파괴 과정 중 어떤 현상이 더 우세한지 그 경쟁관계를 파악하여 플럭의 크기의 증감을 예측할 수 있게 농도(?)와 난류소산매개변수(?)를 이용하여 $c/G^{0.5}$로 매개화하였다. 실험 결과, 순방향 흐름을 제외하고 스토크스파 흐름 조건을 이용하여 진행된 모의에서는 플럭의 크기와 농도가 반비례하는 현상을 관찰할 수 없었으며 $c/G^{0.5}$ 의 변화 역시 흐름의 속도와 농도가 더 큰 지점에서 큰 값을 가지는 일반적인 결과를 나타내었다. 그러나 같은 조건에서 순방향흐름을 추가하여 모의한 결과에서는 플럭의 크기와 농도가 반비례하는 현상을 나타냈다. 연직 방향 $c/G^{0.5}$의 변화를 나타낸 그래프에서 응집과 파괴의 우세에 따라 $c/G^{0.5}$ 가 역전되는 현상을 확인하였다. 즉, 플럭의 크기는 난류의 구조와 그 영향에 의해 농도와 비례관계를 갖지 않을 수도 있다고 판단된다. 또한 본 연구에서 정상류 흐름 조건의 유무에 따라 플럭의 크기와 농도가 비례하거나 반비례하는 상반된 결과를 보였다. 정상류 흐름 조건이 난류의 강도에 큰 역할을 하며 이에 따라 비선형 관계에 영향을 끼친다는 것을 발견하였다. 그러나 흐름의 영향에 대한 더 자세한 분석은 본 연구에서 진행되지 않았으며 향후 연구 시에 분명히 고려되어야 할 사항이다.

• Tuberculosis and Respiratory Diseases
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• v.52 no.1
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• pp.46-53
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• 2002

Background: Pulmonary aspergilloma is relatively common in korea. It arises from the colonization and proliferation of Aspergillus in preexisting lung parenchymal cavities, in particular tuberculosis. The most common symptom in this disorder is hemoptysis, which mayor may not be massive and life threatening. A routine chest radiography and computed tomography (CT) are the most important diagnostic procedures. A surgical resection of the aspergilloma has recently been recommended, because of the relatively low incidence of postoperative complications than in the past. A more concentrated sample of patients with aspergilloma, who either underwent a thoracotomy or tested positive for aspergillus antibodies, were reviewed. Method : The medical records of twenty-two patients with aspergilloma, who had a proven thoracotomy (9 cases), or who tested positive for the diagnostic procedure and/or aspergillus antibodies (13 cases) from January 1995 to December 2000, were reviewed retrospectively. Results : The most common underlying lung disease was a current or old healed tuberculosis, and 3 patients had cultures of mycobacterium other than tuberculosis (MOTT). The mean time until the aspergilloma was detected 5.91 years in the healed tuberculosis cases. The others cases involved a lung abscess, bronchiectasis and without lung disease. The extrapulmonary disease was alcoholism and diabetes. Hemoptysis was most common in 72.7%. A computed tomography (CT) is useful for diagnosis. The right upper lobe, especially the posterior segment, is the most common location. Bronchial artery embolization is ineffective for a long term follow-up. A lobectomy is most common in a thoracotomy, and intra-operative and post-operative complications are rare. During follow-up, the mortality rate, not from the aspergilloma but from respiratory failure, was 13.6%. Conclusion : Aspergilloma is a common cavitary lung disease, It mainly arises from tuberculosis, either current or healed, but extra-pulmonary disease including alcoholism or diabetes are other possible risk factors. Their most common problem in aspergilloma is hemoptysis. Surgery has a low risk of post-operative complications and is recommended in relatively preserved lung function or healthy patients. Medical maneuvers including embolization, and the local insertion of certain materials needs to be studied more closely.

• The Journal of the Petrological Society of Korea
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• v.6 no.1
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• pp.19-33
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• 1997

This study reports the results about the petrography and geochemical characteristics of 10 representative volacanic rocks. The Cretaceous volcanic rocks distributed in the vicinity of the Kageo island composed of andesitic rocks, dacitic welded tuff, and rhyolitic rocks in ascending order. Sedimentary rock is the basement in the study area covered with volcanic rocks. Andesitic rocks composed of pyroclastic volcanic breccia, lithic lapilli tuff and cryptocrystallin lava-flow. Most dacitic rocks are lapilli ash-flow welded tuff. Rhyolitic rocks consists of rhyolite tuff and rhyolite lava flow. Rhyolite tuff are lithic crystal ash-flow tuff and crystal vitric ash-flow tuff with somewhat accidental fragments of andesitic rocks, but dacitic rocks. The variation of major and trace element of the volcanic rocks show that contents of $Al_2O_3$, FeO, CaO, MgO, $TiO_2$ decrease with increasing of $SiO_2$. On the basis of Variation diagrams such as $Al_2O_3$ vs. CaO, Th/Yb vs. Ta/Yb, and $Ce_N/YB_N$ vs. $Ce_N$, these rocks represent mainly differentiation trend of calc-alkaline rock series. On the discriminant diagrams such as Ba/La and La/Th ratio, Rb vs. Y + Nb, the volcanic rocks in study area belongs to high-K Orogenic suites, with abundances of trace element and ternary diagram of K, Na, Ca. According to the tectonic discriminant diagram by Wood, these rocks falls into the diestructructive continental margin. K-Ar ages of whole rocks are from andesite to rhyolite $97.0{\pm}6.8~94.5{\pm}6.6,\68.9{\pm}4.8,\61.5{\pm}4.9~60.7{\pm}4.2$ Ma, repectively. Volcanic rocks in study area show well correlation to the Yucheon Group in terms of rock age dating and geochemcial data, and derived from andesitic calc-alkaline magma that undergone low pressure fractional crystallization dominated plagioclase at <30km.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.99-110
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• 2022

We investigated physicochemical properties and isotopic compositions of organic matter (δ¹³C_TOC and δ ¹⁵N_TN) in the old fish farming (OFF) site after the cessation of aquaculture farming. Based on this approach, our objective is to determine the organic matter origin and their relative contributions preserved at sediments of fish farming. Temporal and spatial distribution of particulate and sinking organic matter(OFF sites: 2.0 to 3.3 mg L^-1 for particulate matter concentration, 18.8 to 246.6 g m^-2 day^-1 for sinking organic matter rate, control sites: 2.0 to 3.5 mg L^-1 for particulate matter concentration, 25.5 to 129.4 g m^-2 day^-1 for sinking organic matter rate) between both sites showed significant difference along seasonal precipitations. In contrast to variations of δ¹³C_TOC and δ¹⁵N_TN values at water columns, these isotopic compositions (OFF sites: -21.5‰ to -20.4‰ for δ¹³ C_TOC, 6.0‰ to 7.6‰ for δ¹⁵N_TN, control sites: -21.6‰ to -21.0‰ for δ¹³C_TOC, 6.6‰ to 8.0‰ for δ¹⁵N_TN) investigated at sediments have distinctive isotopic patterns(p<0.05) for seawater-derived nitrogen sources, indicating the increased input of aquaculture-derived sources (e.g., fish fecal). With respect to past fish farming activities, representative sources(e.g., fish fecal and algae) between both sites showed significant difference (p<0.05), confirming predominant contribution (55.9±4.6%) of fish fecal within OFF sites. Thus, our results may determine specific controlling factor for sustainable use of fish farming sites by estimating the discriminative contributions of organic matter between both sites.