• 한국강구조학회 논문집
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• 제15권2호
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• pp.137-145
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• 2003

본 연구에서는 국산 PS 강봉의 직경, 반복최소응력 및 반복최대응력 등을 실험변수로 하여 직접 인장 피로실험을 수행하였다. 정적 인장실험 결과, 국산 PS 강봉의 응력 - 변형률 곡선과 극한강도 등을 얻었다. 또한, 피로실험에서의 특징적인 실험결과는 PS 강봉의 직경은 피로 수명에 중요한 인자가 아니며, 반복 최소응력의 크기는 국산 PS 강봉의 피로수명에 매우 큰 영향을 미치는 것으로 나타났다. 이러한 피로실험결과를 통계 분석하여 PS 강봉의 응력 범위 및 반복 최소응력 등을 변수로 하는 피로강도 예측식을 제안하였다. 피로실험 중, 시편중앙에 설치한 Extensometer를 이용하여, 변형률의 변화를 측정하였으며, 측정된 변형률 변화현상에서 탄성계수의 변화현상을 구하였다. 변형률 증가현상은 3단계의 형태 즉, 초기에 급격한 증가 후 서서히 증가하며 파괴 직전에 급격하게 증가하는 형태로 나타났다. 탄성계수의 변화현상은 변형률 변화현상과 유사하게 감소하는 것으로 나타났으며 응력수준은 탄성계수 변화에 큰 영향을 주지 않는 것으로 나타났다.

• 공업화학
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• 제19권4호
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• pp.421-426
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• 2008

본 연구에서는 다양한 조성의 다중벽 탄소 나노튜브/폴리스티렌 복합체들을 유화제를 이용한 용액공정을 이용하여 제조하였다. 이때, 분자량이 다른 3종의 폴리스티렌(PS-1 : ${\bar{M}}_n$ = 101500 g/mole, PS-2 : ${\bar{M}}_n$ = 89900 g/mole, PS-3 : ${\bar{M}}_n$ = 85000 g/mole)을 사용하였다. 복합체에서 매트릭스로 사용된 폴리스티렌의 임계흐름온도($T_{cf}{\sim}195^{\circ}C$) 이상과 이하인 $210^{\circ}C$ 및 $180^{\circ}C$에서의 열적 거동을 동적 유변측정기를 이용하여 측정하였다. 복합체의 저장 탄성율, 손실탄성율 및 용융점도는 복합체내에서 다중벽 탄소 나노튜브 함량이 증가함에 따라 증가하였으며, 용융점도의 경우에는 다중벽 탄소 나노튜브 함량이 2 wt%에서 5 wt% 사이에서 가장 큰 증가가 관찰되었다. $210^{\circ}C$의 유변특성 거동에 의하면, 특정 다중벽 탄소 나노튜브 함량에서 복합체의 점성 특성이 탄성특성으로 전이되는 현상이 관찰되었으며, 이때 다중벽 탄소 나노튜브 함량은 MWCNT/PS-1, MWCNT/PS-2 및 MWCNT/PS-3 조성에 대해 각각 3.5 wt%, 3.2 wt 및 3.0 wt%를 나타내었다.

• Korean Journal of Acupuncture
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• 제23권2호
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• pp.155-166
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• 2006

Objectives: This study was undertaken to determine if Plantaginis Semen(PS) has a protective effect against $CCI_4$ induced hepatoxicity in Rats. Methods: The experimental groups were divided into Normal group (untreated Group), Control group $(group\;treated\;with\;CCI_4)$, Sample 1 (group treated with 0.1 ml Plantaginis Semen herbal acupuncture in both sides of $G\bar{a}nsh\bar{u}\;(BL_{18})$ after $CCI_4$ treating) and Sample 2 (group treated with feeding of 1 cc Plantaginis Semen extraction after $CCI_4$ treating). Rats were administered orally $CCI_4\;(0.1\;ml/kg)$ for 4 days. In experiments for PS effect, rats of Sample 1 group received 0.lml herbal acupuncture of PS extraction in both sides of corresponding $G\bar{a}nsh\bar{u}\;(BL_{18})$ of human body for 3 days after treated $CCI_4$. Rats of Sample 2 group feeded PS extraction (1cc) for 3 days after treated $CCI_4$. Variation of weight and biochemical assays (AST, ALT, LDH, ALP, total cholesterol, triglyceride, total protein, albumin) were performed. Results: In Control group, $CCI_4$ increased serum AST, ALT, LDH, ALP, total protein, albumin and decreased weight, total cholesterol, triglyceride. Sample 1 and Sample 2 significantly decreased serum AST, ALT, LDH, ALP, total protein, albumin as compared with Control group. Conclusion: These results indicate that PS could be used in prevention and treatment of hepatoxicity. However, precise mechanisms of PS protection remain to be determined.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.147-148
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• 2009

본 논문에서는 콘크리트 휨부재에 효율적인 프리스트레스를 도입할 수 있는 강봉과 강연선이 일체화된 정착구의 양쪽 연결구의 이동량과 도입긴장력의 관계를 규명하고 설계에 적용할 수 있는 계산식을 유도하였다.

• 열병합발전
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• 통권80호
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• pp.21-27
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• 2011

고전압, 대전류의 송전을 위한 기존의 케이블 포설법과 부스덕트 시공법상 발생하기 쉬운 여러 문제점에 대한 보완 개선되어 새롭게 개발된 HiViPS (High Voltage/Current Insulation Pipe Bus-bar System)라는 복합 차폐 절연관 부스바(Complex Insulation Pipe Tubular Bus-bar)를 소개한다.

• 한국안전학회지
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• 제27권4호
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• pp.50-61
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• 2012

In recent years, various research and developments to introduce composite bridges of new concept have been performed. The types of integral bridge and portal rigid frame bridge are having advantages in bridge maintenance and structural efficiency by eliminating expansion joints and bridge supports. However, the detail of typical girder-abutment connection has problems such as complexity of construction and increase of the construction cost. A new type of bridge, called prestress integral composite girder(PIC girder) bridge, is proposed in this study, which decreases the cost of construction and improves the efficiency of construction by simplifying the detail of construction for girder-abutment connection. PIC girder bridge has the connection detail in which the steel girder and the abutment are integrated by using the PS bar installed in the connection. In this study, finite element analysis and mock-up load test are conducted to evaluate the propriety of design, the effective of fabrication and structural safety for PIC girder bridge. The adequacy of the PIC giredr bridge is verified by the results of static/dynamic load test and finite element analyses.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.173-176
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• 2003

Progressive failure analysis of steel composite double T-beam is performed to investigate the mechanical effects of steel composite fabricated in the webs of double-T beam to replace concrete placing forms. The analysis is based on nonlinear finite element scheme considering material nonlinearities of concrete, reinforcing bar and PS steel. Four-parameter strength envelope defines the hardening and softening phenomena of concrete with consideration of the various levels of confining pressures. Rankine maximum strength criterion defines the elasto-plasticity of PS steel and reinforcing bar, and Von Mises $J_2$ failure criterion for steel plate which wraps the concrete webs of double T-beam. A 6m long two-span steel composite double T-beam is analyzed and compared with the experimental results.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.311-322
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• 1998

American Society for Testing and Materials (ASTM) standard test method PS 070-97 has been created for measuring fracture toughness of advanced ceramics. PS 070-97 includes three test methods which use beams in bending: chevron notch (CNB), single-edged precracked beam (SEPB), and surface crack in flexure (SCF). Supporting data has been collected through several Versailles Advanced Materials and Standards round robins. This paper discusses the evolution of the standard including the rationale for the choice of the three methods and the specifications in the standard. Progress on Standard Reference material 2100 which will have certified values of fracture toughness is presented.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.555-561
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• 2024

This paper derives material properties of steel bars that simulate the distribution of stress and strain of prestressed tendons used in Prestressed concrete(PSC) girders and presents an optimal material model. ABAQUS software was used to establish the 3D solid model of the PSC girder and strand wire rope for a PS(Prestressed) tendon. Then the model of steel wire rope was imported into the Isight interface plugin directly through the ABAQUS and the Data Matching. In ABAQUS, the contact pairs were established, the models were meshed, the constraints were applied to solve the finite element model and an axial tension of 0.5m/s was loaded to analyze the stress and deformation distributions in the normal working range of the PS strand wire rope. In Data Matching, classical experimental data is fitted to the optimal material properties through finite element analysis and multi-objective optimization. The results show that the steel bar with optimal material properties presents a similar linear area and stress distribution with the PS tendon.

• Elastomers and Composites
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• 제23권2호
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• pp.125-133
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• 1988

The thermal degradation of polymethyl methacrylate(PMMA) blend namely polymethyl methacrylate-polycarbonate(PMMA-PC) blend and polymethyl methacrylate-polystyrene(PMMA-PS) blend were carried out by isothermal method under air at several heating temperature from 220 to $270^{\circ}C$. Molecular weight changes during the thermal decomposition were monitored by means of the viscosity average molecular weight($\bar{M}v$). The viscosity average molecular weight was determined by Gel Permeation Chromatography(GPC). The dominant process in the degradation of PMMA-PC and PMMA-PS blend were main chain scission randomly due to weak links that may be distributed along the polymer backbone and the initial rate which the bonds are broken is not sustained. The infra-red spectra of degraded PMMA-PS blend show that the presence of aromatic ketone band at $1685cm^{-1}$. However, the infra-red spectra of degraded PMMA-PC blend show that the presence of hydroperoxide band at $3450cm^{-1}$. Thus indicating that the weak links are attacked by oxygen from the air and produce hydroperoxide or ketone. The activation energies of PMMA-PC blend and PMMA-PS blend were 18.2 and 17.9 Kcal/mol, respectively.