• YAKHAK HOEJI
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• v.52 no.1
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• pp.43-47
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• 2008

To determine the regulatory roles of PDE4 inhibitor on LPS-induced osteoclastogenesis, we investigated the effect of a PDE4 inhibitor on osteoclast formation in the presence of LPS. A specific PDE4 inhibitor, rolipram, increased LPS-induced osteoclast formation in cocultures. To verify that whether rolipram acts indirectly on osteoblasts, we investigated the TRANCE and COX-2 mRNA expression levels in osteoblasts. Treatment of rolipram increased the expression of TRANCE and COX-2 mRNA in osteoblasts stimulated by LPS. On the contrary, rolipram did not augment the number of osteoclasts differentiated from bone marrow cells by LPS. In conclusion, the stimulation of LPS-induced osteoclast formation by the PDE4 inhibitor are attributable to its indirect effect on osteoblasts, not to their direct effect on bone marrow-derived osteoclast precursors.

• Proceedings of the KSRS Conference
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• v.1
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• pp.51-51
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• 2006

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.93-99
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• 2007

Paulownia coreana inner bark was collected, extracted in 70% acetone, concentrated under reduced pressure and sequentially fractionated using n-hexane, $CH_2Cl_2$, EtOAc and $H_2O$, then freeze dried to give brown powders. A portion of the EtOAc soluble powder was chromatographed on a Sephadex LH-20 column using a serious of aqueous methanol and ethanol-hexane mixture as eluting solvents. Two phenolic acid, $\rho$-courmaric acid and caffeic acid, two isomeric phenylethanoid glycosides, verbascoside and iso-verbascoside, and one epimeric phenylpropanoid glycoside, cistanoside F, were isolated and their structures were elucidated by spectroscopic analysis such as NMR and MS.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.417-420
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• 1998

In this paper the formation mechanism of tail current is analyzed and its effect on GTO turn-off performance is given. The conclusion is that the large tail current will considerably increase the turn-off loss $E_{off}$ and cause the re-triggering during GTO's off-switching, therefore the best design criterion is that the tail current of power GTO must be as low as possible.w as possible.

• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.27-36
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• 2000

The Oktalok nodal connection system is an aesthetic and efficient system. It has been widely used throughout Australia. The paper will briefly introduce the concept and application of the Oktalok nodal system. The existing design method is based on the assumption that the joints are pin-ended, i.e., the rotational stiffness of the joints is zero. However the ultimate capacity of the frame may increase significantly depending on the rotational stiffness of the joints. Stiffness tests and finite element simulations were carried out to determine the rotational stiffness of the Oktalok joints. Column buckling tests and non-linear finite element analyses were performed to determine the member capacity of columns with semi-rigid end conditions. A simple formulae for the effective length factor of column buckling is derived based on the above experimental and theoretical investigations.

• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.1-4
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• 2007

The bark of Juglans mandshurica Maxim. was collected, extracted with acetone-$H_2O$ (7:3, v/v), fractioned with n-hexane, $CH_2Cl_2$ and EtOAc, then each fraction was freeze-dried to give some powders. A portion of the EtOAc (28.4 g) fraction was chromatographed on a Sephadex LH-20 column eluting with a series of MeOH-$H_2O$ and EtOH-hexane mixture. Four gallotannins, gallic acid (1), ellagic acid (2), 1,2,4,6-tetra-O-galloyl-${\beta}$-D-glucose (3) and 1,2,3,4,6-penta-O-galloyl-${\beta}$-D-glucose (4), have been isolated from the EtOAc fraction Their structures were elucidated on the basis of chemical evidence and spectrometric analysis such as NMR and MS. The antioxidant activities on each fraction and the isolated gallotannins were evaluated by DPPH radical scavenging test.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.382-384
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• 2003

지하 30m 암반에 건설된 통신구 터널의 안전성을 검토하기 위하여 콘크리트 라이닝 두께를 지중레이다(Ground Penetrating Radar)와 충격반향기법(Impact-Echo Method)으로 추정하였다. 지중레이다에 의한 콘크리트 라이닝 단면의 연속적인 화상으로부터 라이닝 두께의 상대적인 변화를 파악하였으며, 라이닝 두께가 얇은 구간은 충격반향 기법에 의해 일정 간격으로 두께를 추정하였다. 터널 천장의 라이닝 두께는 31.85cm, 좌측 및 우측 측벽부의 라이닝 두께는 각각 32.45cm. 32.97cm로서 설계 값인 30cm와 비교적 잘 일치하는 것으로 파악되었다. 지중레이다와 충격반향기법을 조합한 본 방법은 터널 라이닝 콘크리트 두께를 추정하는데 있어서 매우 효율적이고 신뢰성 있는 방법으로 분석되었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.49-51
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• 2006

A new data line reduction driving method was developed for high pixel density LCoS microdisplays. Its pixel structures and its corresponding gate line waveform were proposed, too. This idea can fulfill the increasing demand for higher resolution LCoS. In this method, no additional AC power is dissipated, and no more horizontal line time is needed. So this method can be applied to the high resolution microdisplay devices. It prefers being applied to the reflective liquid crystal on silicon microdisplays because of the pixel structure asymmetry and PMOS transistor switches used.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1295-1298
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• 2006

Influences of anti-reflection surface treatment, radius of curvature and ambient illuminance on legibility of reflective-type displays were studied. The results showed that legibility mainly depended on the surface treatment. Better surface treatment also produced less visual fatigue after the letter-search task

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.741-742
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• 2008

On the Internet we are confronted with a huge amount of information in daily lives. However, we do not have system support for storing and managing Internet search results useful for us. To solve this problem, this paper presents a data management system in which search results obtained from wikipedia and a web search engine are organized in a structured way, enabling an easy access to them later.