• Earthquakes and Structures
• /
• 제3권2호
• /
• pp.141-168
• /
• 2012

The Retrofit Yield Spectrum (RYS) is a new spectrum-based device that relates seismic demand of a retrofitted structure with the fundamental design parameters of the retrofit. This is obtained from superposition of Yield Point Spectra with design charts that summarize in pertinent spectrum-compatible coordinates the attributes of a number of alternative retrofit scenarios. Therefore, once the requirements for upgrading a given structure have been determined, the RYS enable direct insight of the sensitivity of the seismic response of the upgraded structure to the preliminary design decisions made while establishing the retrofit plan. By virtue of their spectrum-based origin, RYS are derived with reference to a single mode of structural vibration; a primary objective is to control the contribution of this mode in the retrofit design so as to produce a desirable distribution of damage at the ultimate limit state by removing soft storey formations and engaging the maximum number of structural members in deformation, in response to the input motion. Calculations are performed with reference to the yield-point, where secant stiffness is proportional to the flexural strength of reinforced concrete members. Derivation and use of the Retrofit Yield Spectra (RYS) refers to the seismic demand expressed either in terms of spectral acceleration, spectral displacement or interstory drift, at yield of the first storey. A reinforced concrete building that has been tested in full scale to a sequence of simulated earthquake excitations is used in the paper as a demonstration case study to examine the effectiveness of the proposed methodology.

• Structural Engineering and Mechanics
• /
• 제30권6호
• /
• pp.713-732
• /
• 2008

Serviceability and durability of the concrete members can be seriously affected by the corrosion of steel rebar. Carbonation front and or chloride ingress can destroy the passive film on rebar and may set the corrosion (oxidation process). Depending on the level of oxidation (expansive corrosion products/rust) damage to the cover concrete takes place in the form of expansion, cracking and spalling or delamination. This makes the concrete unable to develop forces through bond and also become unprotected against further degradation from corrosion; and thus marks the end of service life for corrosion-affected structures. This paper presents an analytical model that predicts the weight loss of steel rebar and the corresponding time from onset of corrosion for the known corrosion rate and thus can be used for the determination of time to cover cracking in corrosion affected RC member. This model uses fully the thick-walled cylinder approach. The gradual crack propagation in radial directions (from inside) is considered when the circumferential tensile stresses at the inner surface of intact concrete have reached the tensile strength of concrete. The analysis is done separately with and without considering the stiffness of reinforcing steel and rust combine along with the assumption of zero residual strength of cracked concrete. The model accounts for the time required for corrosion products to fill a porous zone before they start inducing expansive pressure on the concrete surrounding the steel rebar. The capability of the model to produce the experimental trends is demonstrated by comparing the model's predictions with the results of experimental data published in the literature. The effect of considering the corroded reinforcing steel bar stiffness is demonstrated. A sensitivity analysis has also been carried out to show the influence of the various parameters. It has been found that material properties and their inter-relations significantly influence weight loss of rebar. Time to cover cracking from onset of corrosion for the same weight loss is influenced by corrosion rate and state of oxidation of corrosion product formed. Time to cover cracking from onset of corrosion is useful in making certain decisions pertaining to inspection, repair, rehabilitation, replacement and demolition of RC member/structure in corrosive environment.

• 한방안이비인후피부과학회지
• /
• 제27권3호
• /
• pp.84-95
• /
• 2014

Objective : Ephedra sinica (ES) has has been used as remedy of allergic diseases for a long time in Korea. In the present study, we investigated the anti-allergic effects of ES on experimental allergic asthma mouse model using ovalbumin (OVA). Methods : BALB/c mice were sensitized and challenged with 100 ug of OVA and 1 mg of aluminum potassium sulfate of 0.2 ml phosphate-buffered saline(PBS) intraperitoneally on day 1 and 15. mice were challenged on 3 consecutive days with 5% OVA and AHR was assessed 24 h after the last challenge. we examined the lung histology, airway hyper sensitivity, total inflammatory cell count in bronchoaveloar lavage fluid(BALF), Th2-associated cytokines production and IgE production. Results : ES potently inhibited the lung damage and the development of Penh. ES also reduced the number of BAL cells during OVA-induced allergic asthma. Furthermore, ES inhibited cytokines production such as IL-4, IL-13 productions, and IgE level of serum. Conclusion : These results suggest that ES may inhibit the production of IL-4, IL-13, IgE and infiltration of inflammatory cell and be beneficial oriental medicine for allergic asthma.

• 한국해양공학회지
• /
• 제29권1호
• /
• pp.16-27
• /
• 2015

The design challenges when attempting to obtain sufficient strength for a deepwater steel catenary riser (SCR) include high stress near the hang-off location, an elevated beam-column buckling load due to the effective compression in the touchdown zone (TDZ), and increased stress and low-cycle fatigue damage in the TDZ. Therefore, a systematic strength analysis is required for the proper design of an SCR. However, deepwater SCR analysis is a new research area. Thus, the objective of this study was to develop an overall analysis procedure for a deepwater SCR. The structural behavior of a deepwater SCR under various environmental loading conditions was investigated, and a sensitivity analysis was conducted with respect to various parameters such as the SCR weight, weight of the internal contents, hang-off angle (HOA), and vertical soil stiffness. Based on a deepwater SCR design example, it was found that the maximum stress of an SCR occurred at a hang-off location under parallel loading direction with respect to the riser plane, except for a wave dominant dynamic survival loading condition. Furthermore, the tensile stress governed the total stress of the SCRs, whereas the bending stress governed the total stress at the TDZ. The weight of the SCR and internal contents affected the maximum stress of the SCR more than the HOA and vertical soil stiffness, because the weight of the SCR, including the internal contents, was directly related to its tensile stress.

• 한국조경학회지
• /
• 제37권4호
• /
• pp.22-31
• /
• 2009

본 연구에서는 무분별한 개발로 인한 자연경관훼손의 예방을 목적으로 자연경관보존방안을 제정하기 위한 경관평가를 수행하였다. 우리나라에서의 경관평가는 개발계획에 따른 시각경관만을 평가하고 있는 현실이며, 경관의 생태적 본질까지 동시에 평가하지는 못하고 있는 실정이어서 이에 대한 대책이 요구되고 있다. 본 연구에서는 이를 위해 시각경관민감도와 생태경관다양성을 요소로 하는 경관평가를 진행하였다. 경관평가의 목적은 실질적인 보존지역을 설정하고 그에 따른 계획을 수립하기 위함이기 때문에 이앤 맥하그(Ian McHarg)의 도면중첩법을 적용한 지리정보시스템(Geographic Information System: GIS)를 활용하였으며, 생태경관다양도와 시각경관민감도를 측정하여 중첩분석하였다. 또한, 경관영향요소의 영향력분석을 통해 집중관리지역을 분석할 수 있었다.

• 한국도로학회논문집
• /
• 제11권2호
• /
• pp.111-120
• /
• 2009

본 연구는 배수성 아스팔트 포장의 표면을 아크릴 수지로 코팅 처리할 경우 내구성 측면 및 기능적 측면에서 어떠한 효과가 있는가를 실내시험을 통해 평가하는 기초적인 연구이다. 포장의 내구성 측면에서는 칸타브로 및 휠트래킹, 수분손상 간접 인장 피로 시험 등을 실시하였다. 시험결과 시편을 수지로 코팅을 한 경우 칸타브로 손실률이 3배 정도 감소되었고 균열에 대한 저항성도 대폭 향상되었으나 수분손상 및 소성변형의 저항성은 큰 차이가 없는 것으로 나타났다. 기능적인 측면에서는 코팅 전 후의 투수계수 및 공극률 BPT(British Pendulum Tester)를 사용한 미끄럼 저항성의 변화를 측정하였다. 시험결과 공극률 및 투수계수는 약간 저하되나 기능상의 문제는 없을 것으로 판단되며, 미끄럼 저항성은 규사를 살포하지 않을 경우 미끄럼 저항성이 감소되나 규사를 살포할 경우 코팅 전 수준 이상의 미끄럼 저항성을 확보하는 것으로 나타났다.

• 한국식품저장유통학회지
• /
• 제8권2호
• /
• pp.206-212
• /
• 2001

Water extract of green tea(GTW) and 70% ethanol extract of green tea(GTE) were prepared for the test of antibacterial activity. The sensitivity of Staphylococcus aureus and Salmonella typhimurium to the green tea extracts in various pH of culture broth was tested. Tryptic soy broth(TSB) containing 0∼2%(w/v) of green tea extracts was adjusted to pH 5.0∼7.0 and inoculated with 10$\^$5/∼10$\^$6/ cells/ml of each bacteria. The plate counting method and clear zone test were used to determine inhibitory effect of green tea extracts. Green tea extracts completely inhibited the growth of S. aureus at 0.5% level and bactercidal at 0.5∼1.0% level of GTW and GTE at pH 5.0∼7.0. Green tea extracts were bactercidal to S. typhimurium at 1.5∼2.0% level of GTW and 1.0∼2.0% level of GTE at pH 7.0. Sal. typhimurium was more resistant than S. aureus. in same concentration of green tea extracts at same pH. The resistance of S. aureus and Sal. typhimurium was increased with decreasing pH of culture broth. The morphology of S. aureus cells treated with green tea extracts showed damage of cell wall and cytoplasmic membrane. Severely damaged cells of S. aureus lost electron dense material and cytoplasm. Green tea extracts stimulated autolysis and cell death of S. aureus. This result suggests that green tea extracts can be used as an effective natural antibacterial agent in food.

• 대한핵의학회지
• /
• 제15권2호
• /
• pp.35-41
• /
• 1981

The radioimmunoassay of human thyrtropin was performed in various thyroid diseases, using the antin-h-TSH antibody (Daiichi, Japan) and purified h-TSH(Biodata, Italy). $^{125}I$ labelling of h-TSH was performed using a small amount $(1.8{\mu}g)$ of chloramin-T as an oxidant at room temperature. This new method facilitated uniform labelling and reduced to damage of h-TSH by chloramin-T, and satisfactory radioimmunoasasy results were obtained with $^{125}I-TSH$ prepared by the new method until at least 7 weeks after preparation, The assay sensitivity was $1.0{\mu}u/ml$. The coefficient of variances in within assay and interrun assay were all less than 10% among the range of $1.25{\mu}u/ml$ and $160{\mu}u/ml$. The serum TSH values by this new method were colsely related to those by commercial kit (r= 0.996).

• 한국화재소방학회논문지
• /
• 제18권4호
• /
• pp.64-71
• /
• 2004

본 논문에서는 NIST에서 개발한 CFAST 화재 모델링 코드를 사용하여 원자력발전소 펌프실 화재를 모의하였다. 급기 제한, 최소 산소 농도(Lower Oxygen Limit), 복사열 방출비율(Radiative Fraction), 방화문 개방 정도 등의 CFAST 입력 변수 변화에 따라 화재 성장 변화를 분석하였다. 분석 결과에 의하면 본 화재구역에서의 화재는 환기 지배형 화재이므로 급기 제한 및 최소 산소 농도 10%로 설정하는 것이 타당한 것으로 판단되며, 복사열 방출에 따라 상부층 가스 온도는 큰 변화가 없는 것을 알 수 있었다. 화재가 발생한 화재구역 내 펌프를 제외하고는 상부에 위치한 케이블은 모두 건전성을 유지하는 것으로 나타났으며, CCDP(Conditional CDP)를 평가한 결과 9.25E-07로, 화재위험도분석보다 현실적이고 불확실성이 감소한 결과를 도출할 수 있었다.

• The Korean Journal of Pain
• /
• 제11권1호
• /
• pp.165-168
• /
• 1998

Although the incidence of epidural abscess is low, patient requiring continuous epidural analgesia for control of acute and chronic pain is increasing rapidly. Therefore we anticipate more frequent encounters with epidural abscess patients in future. Once epidural abscess formation begins, early diagnosis and treatment is very important to prevent permanent neurologic damage. The authors encountered a case of epidural abscess after continuous epidural analgesia for control of perineal pain due to rectal cancer. Forty-eight hours after the block, patient began to suffer severe low back pain, local tenderness, and fever. So the catheter was removed and culture sensitivity test was done with blood and local drainage. The test results identified methicillin susceptible staphylococcus aureus. Antibiotics were administered. Ten days after the block, left ankle jerk disappeared, and force of dorsiflexion of great toe decreased, but numbness or anesthesia appeared at $L_5$ dermatome. Laminectomy was performed, and abscess and necrotic fat material was removed from left $L_5$ nerve root. The patient was discharged 12 days after operation without any neurologic sequalae.