• 전자공학회논문지
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• 제51권5호
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• pp.35-43
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• 2014

본 논문에서는 이동하는 항공기의 통신장비와 지상 통신장비 간의 무선통신 링크 유지 및 통신신호 추적을 위하여 모노펄스 시스템과 ${\alpha}{\beta}$ 필터가 결합된 통신신호 추적 시스템의 성능향상 방안을 제시한다. 모노펄스 오차각 추적을 위하여 일반적으로 사용되는 모노펄스 기울기 곡선(Monopulse Ratio Curve)에 의한 추적 방식이 아닌 최소거리 연산방식을 제안하며, 통신 신호의 일시적 단절 상황에서 모노펄스 추적 재연결 확률 및 추적 정확도 향상을 위하여 가변 이득 방식의 ${\alpha}{\beta}$ 필터 알고리즘을 제안한다. 프로토타입 안테나로 측정한 MR Curve를 이용하여 제안된 모노펄스 시스템의 성능향상을 확인할 수 있다. 또한, 통신 단절 및 연결 상황에서 항공기 모의궤적을 이용한 모의실험은 고정 이득 방식의 ${\alpha}{\beta}$ 필터 대비 가변 이득 방식의 ${\alpha}{\beta}$ 필터 알고리즘의 성능향상을 보여준다. 본 논문에서 제시한 방식은 기존 통신신호 추적 시스템의 하드웨어에 대한 변경 없이 알고리즘의 변경만으로 가능하기 때문에 최소비용을 통한 성능향상을 기대할 수 있다.

• 대한치과보철학회지
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• 제46권3호
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• pp.246-254
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• 2008

STATEMENT OF PROBLEM: The cast abutment has advantages of overcoming angulation problem and esthetic problem. However, when a gold-machined UCLA abutment undergoes casting, the abutment surfaces in contact with the implant may change. PURPOSE: The purpose of this study was to compare the detorque values of prefabricated machined abutments with gold-premachined cast-on UCLA abutments before and after casting in two types of internal implant-abutment connection systems: (1) internal hexagonal joint, (2) internal octagonal joint. Furthermore, the detorque values of two implant-abutment connection systems were compared. MATERIALS AND METHODS: Twenty internal hexagonal implants with an 11-degree taper and twenty internal octagonal implants with an 8-degree taper were acquired. Ten prefabricated titanium abutments and ten gold-premachined UCLA abutments were used for each systems. Each abutment was torqued to 30 N㎝ according to the manufacturer's instructions and detorque value was recorded. The detorque values were measured once more, after casting with gold alloy for UCLA abutment, and preparation for titanium abutments. Group means were calculated and compared using independent t-test and paired t-test (${\alpha}$=0.05). RESULTS: The results were as follows: 1. The detorque values between titanium abutments and UCLA-type abutments showed significant differences in internal octagonal implants (P<0.05), not in internal hexagonal implants (P>0.05). 2. In comparison of internal hexagonal and octagonal implants, the detorque values of titanium abutments had significant differences between two connection systems on the initial analysis (P<0.05), not on the second analysis (P>0.05) and the detorque values of UCLA-type abutments were not significantly different between two connection systems (P>0.05). 3. The detorque values of titanium abutments and UCLA-type abutments decreased significantly on the second analysis than the initial analysis in internal hexagonal implants (P<0.05), not in internal octagonal implants (P>0.05). CONCLUSION: Casting procedures of UCLA-type abutments had no significant effect on screw loosening in internal implant-abutment connection systems, and UCLA-type abutments showed higher detorque values than titanium abutments in internal octagonal implants.

• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.126-132
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• 2014

PURPOSE. This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (${\alpha}$=0.05). RESULTS. The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION. The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.

• Journal of Acupuncture Research
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• 제22권2호
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• pp.1-12
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• 2005

Objective: With the onset of stroke, white blood cells release several proinflammatory cytokines, including interleukin (IL)-6, IL-10, and tumor necrosis factor $(TNF)-{\alpha}$. It has been proven in previous studies that the release of these cytokines is related to the extent of damage to the brain and to overall prognosis. However, no studies have yet been performed to determine the connection with IL-6 and IL-10. Thus, this study is performed to see whether polymorphisms of IL-6, IL-10, and $TNF-{\alpha}$ genes that show increased serum concentration with the onset of stroke are related to stroke attack in Koreans. Methods : Peripheral blood samples derived from patients with stroke (n=100) and healthy controls (n=100) were taken under informed consent. In subjects with stroke, blood samples were obtained within 24 hours of stroke onset. Genomic DNA was isolated using the Wizard DNA Purification Kit (Promega, Madison, WI). Results : 1. Subjects with Heterozygote (GA) and Homozygote (AA) $TNF-{\alpha}$ gene types showed 2.433 and 20.457 times higher risks of being attacked by stroke, respectively, compared to subjects with wild type (GG) $TNF-{\alpha}$ gene type. The data was still statistically significant after adjusting for age, sex, history of smoking, and history of alcohol drinking. 2. Subjects with Homozygote (CC) IL-6 gene type showed 182.033 times higher risk of being attacked by stroke, compared to subjects with wild type (GG) IL-6 genes. This data was statistically insignificant (p=0.700). The data was still statistically insignificant after adjusting for age, sex, history of smoking, and history of alcohol drinking. 3. Subjects with Heterozygote (GA) and Homozygote (GG) IL-10 gene types showed 8.785 and 3.303 times higher risks of being attacked by stroke, respectively, compared to subjects with wild type (AA) IL-10 genes. The data was still statistically insignificant after adjusting for age, sex, history of smoking, and history of alcohol drinking. Conclusion : Our results suggest that the investigated $TNF-{\alpha}$ and IL-10 gene polymorphisms play an important role in stroke attack, but IL-6 gene polymorphism has not been found to associated with stroke.

• 생명과학회지
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• 제13권2호
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• pp.236-240
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• 2003

인간의 면역계는 외부의 병원균 등의 침입에 대하여 매우 강력한 방어작용을 수행하고 있다. 하지만, 때로 면역계의 손상으로 인해 비정상적인 면역작용이 유발됨으로써 면역성 질환이 야기되기도 한다. 특히, 자가면역 질환은 그 종류가 매우 다양하며 심각한 위험을 초래하기도 한다 이들 질환에 대한 활발한 병인학적 연구가 진행되고 있으나, 아직 정확한 메커니즘을 밝히지는 못하고 있다. 자가면역성 당뇨병의 원인 유전자로 인간의 게놈에 내생하고 있는 HERV가 거론된 후, 사이토카인의 변화나 외생 레트로바기러스의 감염에 의해 HERV의 발현이 활성화되어 superantigen으로 작용함으로써 비정상적인 면역반응이 유도된다는 새로운 사실이 밝혀져 많은 주목을 끌고 있다. 이는 내생 레트로바이러스 유래의 superantigen과 인간의 질병과의 관련성을 비교적명확하게 제시함으로써, 자가면역 질환의 극복을 위한 향후 연구에 주요한 실마리를 제공하고 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.405-411
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• 2015

최근 저탄소 녹색성장 및 그린에너지 개발 정책에 힘입어 외연기관의 일종으로 스털링엔진에 대한 관심이 고조되고 있다. 스털링엔진은 크게 ${\alpha}$, ${\beta}$, ${\gamma}$-type의 3가지 방식으로 구분되어지며 그 중 ${\gamma}$-type 엔진의 설계가 용이하고 다양한 적용이 가능하다는 특징이 있음에도 실린더와 크랭크간의 접속거리 문제로 인하여 ${\alpha}$, ${\beta}$-type에 비하여 용적을 크게 차지하는 문제가 있었다. 이를 해결하기 위한 한 방안으로 주로 ${\alpha}$-type에 적용하는 Yoke crank를 응용하면 용적을 줄임과 동시에 실린더의 병렬화에도 유리하다. 금번 연구에서는 기존의 Ross Yoke crank 설계기법에서 개선하여 ${\gamma}$-type 스털링엔진의 Yoke crank 설계를 더욱 단순하고 효율적으로 적용할 수 있는 방법을 제시하였다.

• BMB Reports
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• 제46권9호
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• pp.429-438
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• 2013

Aging is the strongest risk factor for cancer development, suggesting that molecular crosstalks between aging and tumorigenesis exist in many cellular pathways. Recently, Sirtuins (Sirt1-7), the mammalian homologues of aging-related $sir2{\alpha}$ in yeast, have been shown to modulate several major cellular pathways, such as DNA repair, inflammation, metabolism, cell death, and proliferation in response to diverse stresses, and may serve as a possible molecular link between aging and tumorignenesis. In addition, growing evidence suggests that sirtuins are directly implicated in the development of cancer, and they can act as either a tumor suppressor or promoter, depending on the cellular context and tumor types. While the functions of Sirt1 in tumorigenesis have been reported and reviewed in many studies, the connection between sirtuins 2-7 and the development of cancer is less established. Thus, this review will present the recent updates on the emerging roles of Sirt2-7 members in carcinogenesis.

• Ocean and Polar Research
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• 제25권4호
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• pp.617-623
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• 2003

Organisms living in the Arctic and Antarctic regions are exposed to strong constraints, of which temperature is a driving factor. Evolution has led to special adaptations, some with important implications at the biochemical, physiological, and molecular levels. The northern and southern polar oceans have very different characteristics. Tectonic and oceanographic events have played a key role in delimiting the two polar ecosystems and influencing evolution. Antarctica has been isolated and cold longer than the Arctic; its ice sheet developed at least 10 million years earlier. As an intermediate system, the Arctic is a connection between the more extreme, simpler Antarctic system and the very complex temperate and tropical systems. By studying the molecular bases of cold adaptation in polar fish, and taking advantage of the information available on hemoglobin structure and function, we analysed the evolutionary history of the ${\alpha}\;and\;{\beta}globins$ of Antarctic and Arctic hemoglobin using the molecular clock hypothesis as a basis for reconstructing the phylogenetic relationships among species.

• International Journal of Knowledge Content Development & Technology
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• 제12권1호
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• pp.49-65
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• 2022

This study examined e-resources usage among polytechnic students in Southwest Nigeria. A descriptive research design was adopted for this study and the population consisted of polytechnic students from The Polytechnic, Ibadan and Federal Polytechnic, Ede. There were 9671 students from both polytechnics. A multi-stage sampling technique was employed with a sample fraction of 5% was drawn from the total number of students in each faculty amounting to 381. A structured questionnaire was the major instrument used for data collection and the questionnaire was pre-tested using Cronbach-alpha to determine the reliability co-efficient. Data obtained was analyzed using SPSS. The study found that the students from both polytechnics are aware of the e-resources and that the e-resources were mainly used for research, class assignment and to update knowledge. The problem such as epileptic power supply, poor internet connection and so on was identified. The study concluded that polytechnic students could benefit immensely from the enormous usage of e-resources particularly for teaching, learning and research. Based on the findings, recommendations were made.

• 대한약리학회지
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• 제29권1호
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• pp.139-148
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• 1993

SCC 12와 SCC 13 세포주는 피부의 상피암 조직에서 유래되었다. 본 연구에서는, 세포배양으로 in vivo 피부의 거의 모든 특징들을 재현할 수 있는 raft 배양법을 이용하여, 두 종류의 상피 암세포주의 진피 침투성 정도를 비교해 보았다. SCC 12 세포주의 raft 배양에서는, collagen matrix로 침투하는 많은 세포군들이 관찰되었고, 또한 기저세포와 유사한 세포들이 분화층 중간에 관찰되었다. 그러나 SCC 13 세포주의 raft 배양에서는 침투성 세포들이 전혀 관찰되지 않았다. 어떤 인자가 SCC 12 세포주의 침투성에 관여하였는지를 조사하기 위하여, 세포이동 또는 matrix 파괴에 관여하는 각종 단백질 즉, type 1 collagenase, Fn, Fn 수용체와 EGF 수용체 등의 기본 생합성속도를 침투성과 비침투성 세포주에서 측정하였다. 그 중 type 1 collagenase의 생합성만이 침투성 세포주에서 현저히 높게 나타났다. 침투성 SCC 12 세포주에서 관찰된 높은 type 1 collagenase 생합성과 이들 세포주의 침투성과의 연관관계 및 그 기작을 조사하기 위하여 두 세포주에서 TGF alpha에 대한 반응의 차이를 조사하였다. 비침투성 세포주에서는, TGF alpha에 의해 type 1 collagenase의 생합성이 처음 12시간 동안에 현저한 증가를 보였으나 24시간부터 그 유도가 down-regulation되는 현상을 보였다. 그러나 침투성 세포는 TGF alpha에 의해 계속적인 type 1 collagenase의 유도를 보였다. 이에 저자들은 EGF 수용체의 down-regulation으로 인해 type 1 collagenase의 down-regulation이 유도되고, 이와 같은 regulation의 결함으로 인해 SCC 12 세포주가 collagen matrix로 침투하는 현상을 나타낼 것으로 제시하였다.