• 한국정보통신학회논문지
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• 제10권7호
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• pp.1214-1221
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• 2006

헤더 압축 기술은 기존의 일반적인 패킷 데이터의 비효율적인 오버 헤드를 줄이기 위한 방안으로 제안되었다. 특히 음성과 같은 실시간 미디어 스트림 경우에는 더욱 큰 오버헤드율을 보이게 되는데, 헤더 압축을 통해 보다 높은 대역폭 효율을 얻을 수 있다. 본 논문에서는 PHR(periodic Header Refresh) 방법과 HR(Header Request) 방법 의 두가지 에러 복구 기법 에 관하여 각각 성능 분석을 실시하였다. 그 결과로 Overhead Rate, Bandwidth Gain, 그리고 Bandwidth Efficiency 등의 분석 결과가 제시되었다.

• Journal of Pharmaceutical Investigation
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• 제22권4호
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• pp.281-287
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• 1992

Omeprazole (OMZ) is very unstable in acidic solution, which selectively inhibit the release of the gastric juice in the gastric mucosa, In order to stabilize (OMZ) in oral solid dosage form, the enteric-coated microcapsules and compression-coated OMZ tablets containing lysine or arginine as stabilizer were prepared and their dissolution and stability test were performed. The haif life of OMZ microcapsules containing arginine was 194 days at $30^{\circ}C$ and OMZ was completely released in 60 min. The half-lives of enteric coated and non-coated compression-coated OMZ tablets with lysine were 292 and 95 days at $30^{\circ}C$, respectively. The half-lives of enteric coated and non-coated compression-coated tablets with arginine were 1752 and 293 days at $30^{\circ}C$, respectively, and OMZ were released completely in 20 min in the 2nd fluid of K.P.VI. Consequently, the enteric-coated compression-coated OMZ tablets with arginine as stabilizer provided a good formulation for oral solid dosage form.

• 대한전자공학회논문지SD
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• 제45권9호
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• pp.57-64
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• 2008

본 논문은 높은 압축 성능을 가진 테스트 데이터 압축 기법을 제안한다. 제안하는 기법은 돈 케어 리맵핑을 이용한 천이 추가 단계와 천이 이전 단계로 구성된다. 실험 결과는 새로운 기법이 가장 높은 성능의 기법들 중 하나인 RL-huffman보다 높은 압축률을 제공하고 더 작은 하드웨어 면적을 필요로 함을 보여준다. 따라서 이 기법은 테스트 데이터 압축을 위한 실제적인 해법으로 널리 쓰일 수 있다.

• Journal of the Korean Wood Science and Technology
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• 제48권4호
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• pp.458-471
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• 2020

Effect of pre-treatment and compression ratio on specific gravity (SG) and dimensional stability improvement of three lesser-used wood species from natural forest area of North Kalimantan Province, Indonesia had been investigated. Hot soaking at 80℃ for 3 hours within 2 and 5% of boron solution was applied as pre-treatment, while compression ratio applied was 20 and 40% from the initial thickness. Densification was conducted using hot pressing machine at 30 kg/㎠ of pressure and 160℃ of temperature for 15 minutes. Specific gravity was measured gravimetrically, while dimensional stability was evaluated through thickness swelling and water absorption as the indicator. Results show that SG of densified wood was influenced by wood species and compression ratio, but not by pre-treatment applied; while dimensional stability was influenced by wood species, compression ratio, and pre-treatment. Specific gravity and water absorption of densified wood was improved significantly. Specific gravity increased 28.86-63.03%, while water absorption decreased 12.80-15.89%. Thickness swelling of 20% densified wood was lower than that of 40% densified wood.

• 소성∙가공
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• 제12권6호
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• pp.588-596
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• 2003

The relationships between evolution of microstructure and mechanical properties of porous Al-3Si-2Mg-2Cu alloy after the foaming and various heat treating were investigated. The foamed alloy having various densities were manufactured by powder compact foaming and heat treated. Then compression test was performed with deformation rate of 0.5/s. The ultimate compression strength was not changed after solution heat treatment but the flow curve after ultimate strength showed very smooth and uniform plateau region. This change of flow curve means that the deformation mechanism is altered from brittle fracture to ductile deformation and the energy absorption property of Al foam is dramatically improved. The improvement of energy absorption without any detriment of mechanical properties is due to that the very brittle precipitation like Al-Cu and Al-Mg was uniformly dissolved in Al matrix after solution heat treatment. And various mechanical properties of Al alloy porous material were improved by 40% with aging of $200^{\circ}C$ and 50min. These improvements are ascribe to the various fine precipitates like $\Omega$ and $\theta$'.

• 대한기계학회논문집A
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• 제31권6호
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• pp.694-700
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• 2007

Recently, a new cellular metal, WBK(Wire woven Bulk Kagome) has been introduced. WBK is fabricated by assembling metal wires in six directions into a Kagome-like truss structure and by brazing it at all the crossings. Wires as the raw material are easy to handle and to attain high strength with minimum defect. And the strength and energy absorption are superior to previous cellular metals. Therefore, WBK seems to be promising once the fabrication process for mass production is developed. In this paper, an upper bound solution for the mechanical properties of the bulk WBK under compression is presented. In order to simulate uniform behavior of WBK consisted of perfectly uniform cells, a unit cell of WBK with periodic boundary conditions is analyzed by the finite element method. In comparison with experimental test results, it is found that the solution provides a good approximation of the mechanical properties of bulk WBK cellular metals except for Young's modulus. And also, the brazing joint size does not have any significant effect on the properties with an exception of an idealized thin joint.

• 전산구조공학
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• 제9권1호
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• pp.151-159
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• 1996

구조용 콘크리트의 비선형 거동을 예측하기 위하여, 압축강도 연화현상, 거시적 및 회전균열모델등의 내용을 포함하고 있는 압축장 응력장 이론(CFT)에 근거한 유한요소법이 개발/제시되었다. 또한, 이와 관련하여 CFT가 암시하는 탄젠트 및 세칸트 재료강성이 반복계산해법의 관점에서 정의/논의되었다. 최종적으로 계산상의 효율성 증대 및 최대하중 이후의 거동 포착에 주안점을 두어 초기재료 강성을 채택한 변위증분법 논리 및 빠른 수렴을 위한 Over-Relaxtion방법이 Isoparametric계의 8-Node요소에 포함/유도되었다. 이와 같이하여 제시된 비선형 해석 프로그램 NASCOM은 응력 혼돈지역에 위치하는 콘크리트 평면요소의 하중 지지능력, 탄성범위 이후의 변형 특성, 균열양상 및 보강근의 항복범위등의 예측을 가능하게 하였다. NASCOM의 제한된 검증을 위하여, Cervenka의 판넬 시험결과에 대한 하중지지능력 및 변형이력등을 예측한 결과가 전체적인 의미에서 실험결과와 상응하는 일치를 나타내었다.

• 융합보안논문지
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• 제9권2호
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• pp.79-84
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• 2009

현재의 동영상 파일은 WMV(Window Media Video)형식과 같은 극일 포맷과 압축 기술들이다. 이 같은 파일 포맷과 압축 기술을 이용한 동영상들은 화질과 압축율에 문제점을 가지고 있다. 이에 본 논문은 Macromedia(Adobe 사가 인수함)사에서 개발한 FLV(Flash Video)와는 다른 FLY 솔루션 EZ-MOV를 설계 및 구현하였다. EZ-MOV는 다음과 같은 장점들을 가지고 있다. 첫째, FLV플레이어가 배속이 가능하며 자체 DRM이 내장 죄어 있어서 불법 녹화가 불가능하고 둘째, WMV 형식 파일을 FLV로 인코딩시에 최대한 50%까지 무손실로 압축이 가능하며 셋째, 버퍼링 없는 동영상 스트리밍이 가능하다. 넷째, 스트리밍 서버 없이도 FLV 파일을 스트리밍으로 서비스가 가능하다. 다섯째, 다운로드와 스트리밍을 병행한 동영상 서비스도 가능하다. 여섯째, 양방향으로의 서비스도 가능하다.

• Membrane and Water Treatment
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• 제6권3호
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• pp.205-224
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• 2015

A novel hydrophilic poly (vinylidene fluoride)/poly (p-phenylene terephthalamide) (PVDF/PPTA) blend membrane was prepared by in situ polycondensation of p-phenylene diamine (PPD) and terephthaloyl chloride (TPC) in PVDF solution with subsequent nonsolvent induced phase separation (NIPS) process. For comparison, conventional solution blend membrane was prepared directly by adding PVDF powder into PPTA polycondensation solution. Blend membranes were characterized by means of viscometry, X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM). The effects of different blending methods on membrane performance including water contact angle (WCA), mechanical strength, anti-fouling and anti-compression properties were investigated and compared. Stronger interactions between PVDF and PPTA in in situ blend membranes were verified by viscosity and XPS analysis. The incorporation of PPTA accelerated the demixing rate and caused the formation of a more porous structure in blend membranes. In situ blend membranes exhibited better hydrophilicity and higher tensile strength. The optimal values of WCA and tensile strength were $65^{\circ}$ and 34.1 MPa, which were reduced by 26.1% and increased by 26.3% compared with pure PVDF membrane. Additionally, antifouling properties of in situ blend membranes were greatly improved than pure PVDF membrane with an increasing of flux recovery ratio by 25%. Excellent anti-compression properties were obtained in in situ blend membranes with a stable pore morphology. The correlations among membrane formation mechanism, structure and performance were also discussed.

• International Journal of Oral Biology
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• 제33권4호
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• pp.155-162
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• 2008

The present study investigated inflammatory hypersensitivity following compression of the trigeminal ganglion in rats. Experiments were carried out on male Sprague-Dawley rats weighing 250-260 g. Under anesthesia, rats were mounted on a stereotaxic frame and injected with $8{\mu}L$ of 4% agar solution through a stainless steel injector to compress the trigeminal ganglion. In the control group, rats underwent a sham operation without agar injection. Injection sites were examined with a light micrograph after compression of the trigeminal ganglion. Air-puff thresholds (mechanical allodynia) were evaluated 3 days before surgery and 3, 7, 10, 14, 17, 21, 24, 30, and 40 days after surgery. Air-puff thresholds significantly decreased after compression of the trigeminal ganglion. Mechanical allodynia was established within 3 days and remained strong over 24 days, returning to preoperative levels approximately 40 days following compression. After subcutaneous injection of 5% formalin ($50{\mu}L$) in the compression of the trigeminal ganglion-treated rats, nociceptive scratching behavior was recorded for 9 successive 5-min internals. Injection of formalin into the vibrissa pad significantly increased the number of scratches and duration of noxious behavioral responses in sham-treated rats. Noxious behavioral responses induced by subcutaneous formalin administration were significantly potentiated in rats with trigeminal ganglion compression. These findings suggest that compression of the trigeminal ganglion enhanced formalin-induced infla-mmatory pain in the orofacial area.