• Journal of the Korea Concrete Institute
• /
• v.21 no.4
• /
• pp.513-521
• /
• 2009

Recently, the externally prestressed unbonded concrete structures are increasingly being built. The mechanical behavior of prestressed concrete beams with external unbonded tendon is different from that of normal bonded PSC beams in that the slip of tendons at deviators and the change of tendon eccentricity occurs as external loads are applied in external unbonded PSC beams. The purpose of the present paper is therefore to evaluate the flexural behavior by performing static flexural test according to tendon area and tendon force. From experimental results, before flexural cracking, there was no difference between external members and bonded members. However, after cracking, yielding load of reinforcement, ultimate load, and the tendon stress of external members was lower than that of bonded members. For the relationship of load-tendon stress, the increasing of tendon strain was inversely proportional to the initial tendon force. However, even if the initial tendon force was large, the tendon strain with small effective stress was smaller than that with large effective stress. The concrete compressive strain was proportional to the effective stress of external tendon. From the comparison between test results and codes, the ACI-318 could not consider the effect of tendon force or effective stress, and especially the results of ACI-318 were very small, so it was very conservative. And the AASHTO 1994 could be influenced on the tendon area, initial force and effective stress, but as it was made on the basis of internal unbonded tendon, its results were much larger than the test results. For this reason, the new correct predict equation of external tendon stress will be needed.

• Journal of the Korea Concrete Institute
• /
• v.21 no.1
• /
• pp.93-103
• /
• 2009

The concept of the effective moment of inertia has been generally used for the deflection estimation of reinforced concrete flexural members. The KCI design code adopted Branson's equation for simple calculation of deflection, in which a representative value of the effective moment of inertia is used for the whole length of a member. However, the code equation for the effective moment of inertia was formulated based on the results of beam tests subjected to uniformly distributed loads, which may not effectively account for those of members under different loading conditions. Therefore, this study aimed to verify the influences of moment shapes resulting from different loading patterns by experiments. Six beams were fabricated and tested in this study, where primary variables were concrete compressive strengths and loading distances from supports, and test results were compared to the code equation and other existing approaches. A method utilizing variational analysis for the deflection estimation has been also proposed, which accounts for the influences of moment shapes to the effective moment of inertia. The test results indicated that the effective moment of inertia was somewhat influenced by the moment shape, and that this influence of moment shape to the effective moment of inertia was not captured by the code equation. Compared to the code equation, the proposed method had smaller variation in the ratios of the test results to the estimated values of beam deflections. Therefore, the proposed method is considered to be a good approach to take into account the influence of moment shape for the estimation of beam deflection, however, the differences between test results and estimated deflections show that more researches are still required to improve its accuracy by modifying the shape function of deflection.

• Korean Chemical Engineering Research
• /
• v.50 no.6
• /
• pp.1002-1007
• /
• 2012

The considerable portion of energy demand has been satisfied by the combustion of fossil fuel and the consequent $CO_2$ emission was considered as a main cause of global warming. As a technology option for $CO_2$ emission mitigation, absorption process has been used in $CO_2$ capture from large scale emission sources. To set up optimal operating parameters in $CO_2$ absorption and solvent regeneration units are important for the better performance of the whole $CO_2$ absorption plant. Optimal operating parameters are usually selected through a lot of actual operation data. However theoretical approach are also useful because the arbitrary change of process parameters often limited for the stability of process operation. In this paper, a theoretical approach based on vapor-liquid equilibrium was proposed to estimate optimal operating conditions of $CO_2$ absorption process. Two $CO_2$ absorption processes using 12 wt% aqueous $NH_3$ solution and 20 wt% aqueous MEA solution were investigated in this theoretical estimation of optimal operating conditions. The results showed that $CO_2$ loading of rich absorbent should be kept below 0.4 in case of 12 wt% aqueous $NH_3$ solution for $CO_2$ absorption but there was no limitation of $CO_2$ loading in case of 20 wt% aqueous MEA solution for $CO_2$ absorption. The optimal regeneration temperature was determined by theoretical approach based on $CO_2$ loadings of rich and lean absorbent, which determined to satisfy the amount of absorbed $CO_2$. The amount of heating medium at optimal regeneration temperature is also determined to meet the difference of $CO_2$ loading between rich and lean absorbent. It could be confirmed that the theoretical approach, which accurately estimate the optimal regeneration conditions of lab scale $CO_2$ absorption using 12 wt% aqueous $NH_3$ solution could estimate those of 20 wt% aqueous MEA solution and could be used for the design and operation of $CO_2$ absorption process using chemical absorbent.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.41 no.1
• /
• pp.51-59
• /
• 2013

This study was conducted to compare the sizes of effective values, which users recognize, according to the kinds of physical and psychological services provided by an arboretum, by estimating them in monetary values. As an analysis tool for this purpose, the CE(Choice Experiments) method, which is able to estimate effective value's size depending on each variable, was employed. For drawing up profiles for estimation of the values of individual services, 25 profiles were extracted using the orthogonal design of the SPSS statistical package, and questions of 75 pairs were created not to make each of the profiles overlapped. Then, each user was given three questions at five sets each and 3,510 data were used for the analysis. As the result, in relation to the attribute, 'The kinds of trees should be diversified 50% more than now.', firstly, users showed the biggest willingness to pay, based on the present level, and expressed intentions to pay 7,956 won, additionally. Secondly, the value of the path design that was unique than the present road design was estimated in 6,025 won, and when individual attendants guided visitors in the arboretum, they expressed intentions to pay nearly three times more expenses than when they were guided as a group. These results show that users in the Gyeongnam Arboretum recognized the highest effective values towards the collection and display of trees that are arboretum's original functions, and it was followed by the unique road design to observe a variety of dense trees well. This research could be useful in comparing or measuring particular effective values of users that central operators of arboretums want to know. Moreover, it would be suggested as an advanced research for providing basic data about value estimation of individual environmental goods not only in arboretums, but also in other fields.

• Journal of agricultural medicine and community health
• /
• v.38 no.4
• /
• pp.243-256
• /
• 2013

Objectives: This study was to investigate fear of falling and related factors in elderly living alone based on fall experience. Methods: Participants were 404 elderly women(faller=148, non-faller=256) over 65 years who were homebound living alone in Jeollanam-do Province. Face-to-face interviews were conducted using questionnaires from April $23^{th}$ to June $9^{th}$ 2013. The questionnaires consisted of demographic variables, fall experience, Fear of falling questionnaire(FOFQ), Falls Efficacy Scale(FES) and Center for Epidemiologic Studies Depression(CES-D). The collected data were analyzed using the SPSS version 14.0. Results: The fear of falling and the influential factors were different according to fall experience. Regression model for fear of falling in fallers significantly accounted for 46.1%(F=6.71, p<0.001); difficulty of performing activity, depression, fall-efficacy, static balance and assistive devices. Regression model for fear of falling in non-fallers significantly accounted for 55.2%(F=15.16, p<0.001); fall-efficacy, environmental hazards, difficulty of performing activity, risk of nutrition, housing type, dizziness and assistive devices. Conclusion: Results demonstrate that fall is an important health problem for elderly women living alone, and show fall experience for factors influencing fear of falling. These results could be used in the developing fall prevention programs.

• Journal of the Korea Concrete Institute
• /
• v.19 no.4
• /
• pp.515-525
• /
• 2007

In this investigation, results of laboratory tests on four reinforced concrete flat plate interior connections with elongated rectangular column support which has been used widely in tall residential buildings are presented. The purpose of this study is to evaluate an effect of column aspect ratio (${\beta}_c={c_1}/{c_2}$=side length ratio of column section in the direction of lateral loading $(c_1)$ to the direction of perpendicular to $c_1$) on the hysteretic behavior under earthquake type loading. The aspect ratio of column section was taken as $0.5{\sim}3\;(c_1/c_2=1/2,\;1/1,\;2/1,\;3/1)$ and the column perimeter was held constant at 1200mm in order to achieve nominal vertical shear strength $(V_c)$ uniformly. Other design parameters such as flexural reinforcement ratio $(\rho)$ of the slab and concrete strength$(f_{ck})$ was kept constant as ${\rho}=1.0%$ and $f_{ck}=40MPa$, respectively. Gravity shear load $(V_g)$ was applied by 30 percent of nominal vertical shear strength $(0.3V_o)$ of the specimen. Experimental observations on punching failure pattern, peak lateral-load and story drift ratio at punching failure, stiffness degradation and energy dissipation in the hysteresis loop, and steel and concrete strain distributions near the column support were examined and discussed in accordance with different column aspect ratio. Eccentric shear stress model of ACI 318-05 was evaluated with experimental results. A fraction of transferring moment by shear and flexure in the design code was analyzed based on the test results.

• Journal of Hospice and Palliative Care
• /
• v.13 no.4
• /
• pp.232-242
• /
• 2010

Purpose: This study was done to investigate effects of foot massage and supportive communication provided by hospice volunteers on depression, anxiety, and mood of cancer patients who are going under intravenous chemotherapy at out patient department (OPD). Methods: A non-equivalent control group non-synchronized design was used. Sixty-four participants were recruited from out-patients setting in a university hospital by a convenient sampling. Two trained- hospice volunteers first provided regular hospice volunteer service to 34 patients in the control group. Subsequently, foot massage and supportive communication were provided to 30 participants in the experimental group. After the intervention, all participants answered the structured questionnaire with visual analog scales on depression, anxiety, and mood including general characteristics. Data were analyzed using descriptive statistics, two sample t-test, and paired t-test by PASW 17. Results: After the intervention, changes in negative moods, i.e. strain and powerlessness in the experimental group were significantly different from those in control group; strain and powerlessness in the experimental group were significantly decreased by foot massage and supportive communication provided by hospice volunteers. Conclusion: The current findings provide an empirical evidence of a brief and efficacious intervention for cancer patients. Further studies are warranted with larger sample size to validate the effectiveness of foot massage and supportive communication as a solid intervention for cancer patients who are undergoing intravenous chemotherapy at OPD.

• Radiation Oncology Journal
• /
• v.20 no.2
• /
• pp.165-171
• /
• 2002

Purpose : In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. Materials and Method : A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetrie image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was peformed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. Results : CSI in the supine position was successfully peformed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The differences between the DRRs and the portal films were less than 3 mm in the vertebral contour. Conclusion : CSI in the supine position is feasible in patients who cannot lie on prone position, such as pediatric patienta under the age of 4 years, patients with a poor general condition, or patients with a tracheostomy.

• Microbiology and Biotechnology Letters
• /
• v.41 no.1
• /
• pp.17-25
• /
• 2013

The thermotolerant methylotrophic yeast Hansenula polymorpha is an attractive model organism for various fundamental studies, such as the genetic control of enzymes involved in methanol metabolism, peroxisome biogenesis, nitrate assimilation, and resistance to heavy metals and oxidative stresses. In addition, H. polymorpha has been highlighted as a promising recombinant protein expression host, especially due to the availability of strong and tightly regulatable promoters. In this study, we investigated the possibility of employing human serum albumin (HSA) as the fusion tag for the secretory expression of heterologous proteins in H. polymorpha. A set of four expression cassettes, which contained the methanol oxidase (MOX) promoter, translational HSA fusion tag, and the terminator of MOX, were constructed. The expression cassettes were also designed to contain sequences for accessory elements including His8-tag, $2{\times}(Gly_4Ser_1)$ linkers, tobacco etch virus protease recognition sites (Tev), multi-cloning sites, and strep-tags. To determine the effects of the size of the HSA fusion tag on the secretory expression of the target protein, each cassette contained the HSA gene fragment truncated at a specific position based on its domain structure. By using the Green fluorescence protein gene as the reporter, the properties of each expression cassette were compared in various conditions. Our results suggest that the translational HSA fusion tag is an efficient tool for the secretory expression of recombinant proteins in H. polymorpha.

• Journal of Animal Science and Technology
• /
• v.45 no.1
• /
• pp.33-40
• /
• 2003

The present study was undertaken to find relationships of plasma insulin-like growth factor (IGF)-I and IGF-II concentrations to litter size and lactation performance. Sixty pure-bred Landrace and Yorkshire pigs having similar farrowing weeks which had been selected from a large number of pregnant gilts and sows were divided into low- (<${\mu}$－0.5SD) and high-litter size (>${\mu}$+0.5 SD) lines under a 2 (breed)${\times}$2 (line) factorial arrange of treatments. After adjusting the litter size to nine piglets per sow at farrowing, total litter weight was measured at three weeks postpartum at weaning as an index of milk yield. Blood samples were obtained from the jugular vein at day (d)-90 pregnancy (Px) and at d-15 postpartum. The litter size or the number of piglets born during the present experiment and the average litter size during the entire parities up to the present one were greater in the high-line than in the low-line by 3.7 and 2.4 piglets, respectively (P<0.01); effect of the breed on litter size was not significant. Plasma IGF-II concentration at d-90 Px was greater in the high-line than in the low-line. Litter size and d-90 Px IGF-I concentration were negatively correlated in Landrace (r=－0.46; P<0.05) and tended to be negatively correlated in Yorkshire (r=－0.31; P=0.09), which resulted in a significant negative correlation between these two variables in total animals (r=－0.35; P<0.01). Litter weight at weaning was not different between the two breeds or lines. Relationships between the litter weight and IGF concentration were not consistent across the breed ${\times}$ physiological stage combinations. Results suggest that d-90 Px IGF concentrations may be indicative of the litter size at impending farrowing.