• 터널과지하공간
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• 제14권6호
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• pp.411-422
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• 2004

폐광지역에서 흔히 발생하는 싱크홀 형태의 지반침하는 인근 지역 주민의 안전은 물론, 지상구조물에 심각한 위해 요소로 작용할 수 있다. 본 연구에서는, 이러한 싱크홀의 발생양상을 수치해석적으로 규명하기 위해, 아주 특별한 형태의 유한요소해석을 실시하였다. 특히, 갱도 천반의 붕락에 의해 야기되는 공간이나, 파쇄된 암반이 쌓여서 이루는 폐석더미 등 기존의 수치해석기법으로서는 쉽사리 표현할 수 없었던 현실적인 문제들을 수치적으로 모사하기 위해 active-passive-active 유한요소를 사용하였다. Active 요소 즉 고체 요소는 싱크홀이 형성되는 영역 내에서 인장파괴 기준식을 만족하게 되면 passive 요소 즉 공간 요소로 전환될 수 있다. 싱크홀이 완전히 형성되게 되면 이들 passive요소들은 다시 active요소로 바뀌면서 폐석더미를 수치적으로 모사할 수 있게 된다. 채굴적의 폭, 심도, 천반의 상태 및 붕락 암반의 부피팽창율 등이 싱크홀에 미치는 영향을 검토하기 위해 여러 가지 조건에 의한 유한요소모델이 해석되었다. 본 연구는, 이와 같이 싱크홀이 발생하는 과정이나 천반이 붕락하는 현상 등을 해석하기 위해 수치해석상에서 active-passive-active유한요소들이 효과적으로 사용될 수 있음을 보여준다.

• International Journal of Industrial Entomology and Biomaterials
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• 제16권2호
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• pp.67-74
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• 2008

A line x tester analysis was carried out in mulberry (Morns spp.) under different salinity levels to determine the changes in the genetic interaction of various morpho-biochemical characters. Five mulberry genotypes, 3 females and 2 males, differing in salt tolerance were selected for the study. Clones of these parents along with clones of the F1 hybrids were planted in earthen pots and subjected to different levels of salinity (0.0%, 0.25%, 0.50%, 0.75% and 1.00% NaCl). Data on morphological and biochemical characters were subjected to line x tester analysis. The result revealed significant variation among the parents studied. The prominence of non-additive gene effect under control condition suggests the need for well chalked out breeding program to exploit the non-fixable variance of components for improvement of plant height, leaf size and leaf yield, chlorophyll and photosynthesis in mulberry. However, under salinity stress a shift from non-additive gene effect to additive gene effect for the above said character further suggests the need for a change in breeding strategy. The general combining ability (GCA) analysis has identified English black as the best combiner among the parents and the specific combining ability analysis (SCA) found crosses of English black X C776 and Rotndiloba x Mandalaya were good for Plant height and leaf size and English black X C776 and Rotundiloba x C776 were good for biochemical proline and chlorophyll. From the performance of parents and their crosses under different salinity levels and also under normal cultural conditions it is concluded that in mulberry different approaches are required to develop varieties for the irrigated and saline conditions.

• The Korean Journal of Pain
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• 제31권3호
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• pp.183-190
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• 2018

Background: Vitamin B12 deficiency has been associated with peripheral neuropathy, loss of sensation in the peripheral nerves, and weakness in the lower extremities. Methylcobalamin is the most effective analogue of vitamin B12 used to treat or prevent the complications associated with vitamin B12 deficiency. The current study aimed to compare the serum cobalamin levels after administration of two different regimes of methylcobalamin in peripheral neuropathy patients. Methods: The present study was a prospective, randomized, comparative study. The study consisted of two parallel groups, group A (methylcobalamin $500{\mu}g$ injection intramuscularly three times a week) and group B (methylcobalamin $1500{\mu}g$ injection intramuscularly once a week). A control group of healthy volunteers was also included. Results: A total of 24 patients (12 in each group) were included in the study. Five healthy volunteers were also included as a control in each group. At the end of treatment, serum cobalamin levels were significantly (P = 0.028) higher in group A ($1892.08{\pm}234.50$) as compared with group B ($1438.5{\pm}460.32$). The serum cobalamin levels in Group A healthy volunteers were also two times higher than that of group B (P = 0.056). Both the LANSS scale and DN4 questionnaire reported similar results at end of treatment. Conclusions: The $500{\mu}g$ methylcobalamin thrice weekly regime is more effective in increasing the serum cobalamin levels as compared to the $1500{\mu}g$ methylcobalamin once weekly regime.

• Parasites, Hosts and Diseases
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• 제54권4호
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• pp.393-397
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• 2016

Low parasitemic condition in malaria remains a diagnostic challenge; as the available diagnostic methods failed to detect. Currently, hemozoin (Hz) pigment is gaining attention in the diagnosis of malaria. The major drawback is ease of detection of Hz in routine practice. A pilot study was conducted to evaluate the role of Hz pigment and to compare the performance of quantitative buffy coat assay (QBC) and PCR in such conditions. Clinically suspected cases of malaria were examined by both Giemsa stain and immunochromatographic test (ICT). Samples positive by ICT and negative by Giemsa stain were further examined by nested PCR targeting 18S rRNA and QBC for the presence of malaria parasites and pigments. Thirty blood samples fulfilled the inclusion criteria out of which 23 were Plasmodium vivax (Pv), 4 Plasmodium falciparum (Pf), and 3 mixed (Pv and Pf) by immunochromatographic test. Twenty-one out of 30 (70%) were positive by nested PCR in comparison to 25/30 (83%) by QBC. Samples containing both malaria parasites and Hz pigment by QBC completely showed concordance with the PCR result. However, 61% of total samples containing only Hz pigment were observed positive by PCR. Hz pigment remains an important tool for malaria diagnosis. Identification of leukocytes containing pigments by QBC not only indicates recent malarial infections but also puts light on severity of the disease. QBC assay is a rapid, highly sensitive, and cost-effective method to detect malaria parasites and Hz pigment especially in low parasitemic conditions.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 춘계학술대회논문집; 전남대학교, 19 May 1995
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• pp.344-349
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• 1995

셀구조물은 선박, 항공기, 우주선 등의 산업분야에 자주 사용되는 중요한 구조요소로서, 이에 대한 연구도 공학적 필요성에 의해 많은 연구가 진행되어 왔다. Maddox등의 Rayleigh-Ritz법, Srinivasan and Bobby의 적분방정식 기법, Petyt의 유한요소법, Irie, Henderson등의 전달매트릭스법, 그 외 Webster, Petyt and Deb Nath, Blevins, Srinivasan and Krishnan등에 의해 여러가지 해석방법의 진동해석이 행해져 왔다. 현재 주로 사용되고 있는 매트릭스 구조해석 및 진동해석 방법으로는 유한요소법과 전달매트릭스법을 들 수 있다. 유한요소법은 범용적인 해석 프로그램의 개발은 수월하지만 대규모의 선형 연립방정식의 해법에 귀착되므로, 기억용량이 큰 대형컴퓨터가 필요하고, 반면 전달매트릭스법은 기억용량이 적은 퍼스널컴퓨터로도 계산수행이 가능하나 고차의 고유진동수를 구할 경우나, 중간에 단단한 경탄성지지가 존재할 경우 등에는 수치계산상의 문제점이 지적되고 있다. 이에 대한 대책으로, 상태변수를 바꾸어 넣은 Riccati방법, 각 절점의 기지의 상태변수를 제거하는 Frontal법, 전달매트릭스와 강성매트릭스를 결합시키는 방법 등이 보고 되고 있다. 이에 자자들은 퍼스널컴퓨터 이용에 적합한 고속, 고정도의 구조해석 및 진동해석 기법으로 전달영향계수법을 제안하여, 원판구조물, 사각판구조물, 원통형 셀구조물 등의 여러가지 형상구조물의 자유진동 해석에 적용해서, 종래의 전달매트릭스법에 비해 계산정도 및 계산속도의 양면에서 매우 우수함을 보고한바 있다. 본 연구에서는 동적영향계수의 축차전달에 그 개념을 두고 있는 전달영향계수법을 좀 더 일반화시키고 체계화시키기 위하여 탄성지지를 갖는 셀구조물에 적용하여 자유진동 해석 알고리즘을 정식화한 후, 간단한 모델에 대한 수치실험을 통해서 전달 영향계수법으로 구한 해를 전달매트릭스법의 결과와 비교.검토하여 본 방법의 유용성을 확인하였다.

• Parasites, Hosts and Diseases
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• 제53권6호
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• pp.705-712
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• 2015

Intestinal parasitic infections are one of the major causes of diarrhea in human immunodeficiency virus (HIV) seropositive individuals. Antiretroviral therapy has markedly reduced the incidence of many opportunistic infections, but parasite-related diarrhea still remains frequent and often underestimated especially in developing countries. The present hospital-based study was conducted to determine the spectrum of intestinal parasitosis in adult HIV/AIDS (acquired immunodeficiency syndrome) patients with or without diarrhea with the levels of $CD4^+$ T-cell counts. A total of 400 individuals were enrolled and were screened for intestinal parasitosis. Of these study population, 200 were HIV seropositives, and the remaining 200 were HIV uninfected individuals with or without diarrhea. Intestinal parasites were identified by using microscopy as well as PCR assay. A total of 130 (32.5%) out of 400 patients were positive for any kinds of intestinal parasites. The cumulative number of parasite positive patients was 152 due to multiple infections. A significant association of Cryptosporidium (P<0.001) was detected among individuals with $CD4^+$ T-cell counts less than $200cells/{\mu}l$.

• 한국컴퓨터정보학회논문지
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• 제12권2호
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• pp.63-70
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• 2007

DES는 64비트의 평문을 64비트의 암호문으로 암호화하는 블록 사이퍼 암호 시스템으로 1976년 표준으로 채택되어 20년 동안 전세계적으로 널리 쓰여왔다. 그러나 하드웨어와 암호 해독 기술의 발달로 인해 취약점이 드러난 DEB는 더 이상 안전하지 않기 때문에 암호화 강도를 높인 새로운 암호 시스템이 요구되었다. 이에 따라 여러 가지 방법이 제안되었으며, 그 중에서 NG-DES[1]에서는 키 길이의 확장과 비선형 f함수를 사용하여 기존 DES보다 암호화 강도를 높일 수 있었다. NG-DES는 기존의 DES를 64비트에서 128비트로 확장하면서 각 라운드에 사용되는 Fiestel 구조 또한 확장하였는데. 이 구조는 각 평문 비트 변화가 전체 암호문 비트에 영향을 미치지 못하는 단점을 가지고 있다. 본 논문에서는 NG-DES에서 제안된 확장 Fiestel 구조에서 라운드 간의 입출력 연결을 효과적으로 교차시킴으로써 혼돈과 확산을 증가시켜 암호화 강도를 높인 암호 시스템을 제안한다.

• 전기화학회지
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• 제13권3호
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• pp.181-185
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• 2010

전도성 고분자로 널리 알려진 폴리아닐린과 액체전해질의 핵심 재료인 이온성 액체와의 복합체를 형성시키고 이들의 물리적, 전기화학적인 특성을 조사되었다. 이미다졸늄 이온성 액체 (1-methyl-3-propylimidazolium iodide, PMI-I)에 비전도성 폴리아닐린 (Emeraldine Base)을 30 wt%이상 첨가하였을 때 준고형화 현상이 나타났고, 이온성 액체의 이미다졸늄 양이온의 방향족 고리와 폴리아닐린의 벤족기와의 ${\pi}-{\pi}$ 자기상호조립에 의한 약한 도핑작용을 통해 섬유상 구조를 나타내었으며, 전도도의 변화율은 80%이상 유지하였다.

• 한국재료학회지
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• 제23권3호
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• pp.168-176
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• 2013

In this study, hydroxyapatite (HAp) was incorporated into toothpaste and its effect on the remineralization and restoration of dental enamel was evaluated. Different sets of toothpaste were incorporated with HAp levels of 0%, 5%, 10 %, and 15 %. The filler particles of the resulting toothpaste samples were observed via SEM and XRD and compared with compositions of several commercially available toothpastes, showing that the HAp was successfully incorporated into the toothpaste samples. Different sets of human enamel were inflicted with lesions and then treated with the different fabricated toothpaste samples for five minutes three times a day for seven days. During the treatment, the teeth were subjected to demineralization and remineralization cycles to simulate the effect of natural saliva. The surface of the enamel samples were observed using SEM before and after one week of treatment, showing the formation of HAp layers on the surfaces of the enamel samples. The effect of the toothpaste on the lesions was observed using an inverted light microscope and the lesion depth was found to decrease as the concentration of HAp in the toothpaste used increased. HAp was successfully incorporated in the toothpaste and its presence was found to lessen lesion depths and improve tooth remineralization.

• Interaction and multiscale mechanics
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• 제3권1호
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• pp.95-110
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• 2010

In recent years, study of the static response of pavements to moving vehicle and aircraft loads has received significant attention because of its relevance to the design of pavements and airport runways. The static response of beams resting on an elastic foundation and subjected to moving loads was studied by several researchers in the past. However, most of these studies were limited to steady-state analytical solutions for infinitely long beams resting on Winkler-type elastic foundations. Although the modelling of subgrade as a continuum is more accurate, such an approach can hardly be incorporated in analysis due to its complexity. In contrast, the two-parameter foundation model provides a better way for simulating the underlying soil medium and is conceptually more appealing than the one-parameter (Winkler) foundation model. The finite element method is one of the most suitable mathematical tools for analysing rigid pavements under moving loads. This paper presents an improved solution algorithm based on the finite element method for the static analysis of rigid pavements under moving vehicular or aircraft loads. The concrete pavement is discretized by finite and infinite beam elements, with the latter for modelling the infinity boundary conditions. The underlying soil medium is modelled by the Pasternak model allowing the shear interaction to exist between the spring elements. This can be accomplished by connecting the spring elements to a layer of incompressible vertical elements that can deform in transverse shear only. The deformations and forces maintaining equilibrium in the shear layer are considered by assuming the shear layer to be isotropic. A parametric study is conducted to investigate the effect of the position of moving loads on the response of pavement.