• Title/Summary/Keyword: Stability Limit

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Development and Validation of an HPLC Method for the Pharmacokinetic Study of Fenoprofen in Human (페노프로펜 체내동태 연구를 위한 혈청 중 페노프로펜의 HPLC 정량법 개발 및 검증)

  • Cho, Hye-Young;Kang, Hyun-Ah;Kim, Yoon-Gyoon;Sah, Hong-Kee;Lee, Yong-Bok
    • Journal of Pharmaceutical Investigation
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    • v.35 no.6
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    • pp.423-429
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    • 2005
  • A selective and sensitive reversed-phase HPLC method for the determination of fenoprofen in human serum was developed, validated, and applied to the pharmacokinetic study of fenoprofen calcium. Fenoprofen and internal standard, ketoprofen, were extracted from human serum by liquid-liquid extraction with diethyl ether and analyzed on a Luna C18(2) column with the mobile phase of acetonitrile-3 mM potassium dihydrogen phosphate (32:68, v/v, adjusted to pH 6.6 with phosphoric acid). Detection wavelength of 272 nm and flow rate of 0.25 mL/min were fixed for the study. The assay robustness for the changes of mobile phase pH, organic solvent content, and flow rate was confirmed by $3^{3}$ factorial design using a fixed fenoprofen concentration $(2\;{\mu}g/mL)$ with respect to its peak area and retention time. And also, the ruggedness of this method was investigated at three different laboratories using same quality control (QC) samples. This method showed linear response over the concentration range of $0.05-100\;{\mu}g/mL$ with correlation coefficients greater than 0.999. The lower limit of quantification using 1 mL of serum was $0.05\;{\mu}g/mL$, which was sensitive enough for pharmacokinetic studies. The overall accuracy of the quality control samples ranged from 92.27 to 109.20% for fenoprofen with overall precision (% C.V.) being 5.51-11.71 %. The relative mean recovery of fenoprofen for human serum was 81.7%. Stability (freeze-thaw, short and long-term) studies showed that fenoprofen was not stable during storage. But, extracted serum sample and stock solution were allowed to stand at ambient temperature for 12 hr prior to injection without affecting the quantification. The peak area and retention time of fenoprofen were not significantly affected by the changes of mobile phase pH, organic solvent content, and flow rate under the conditions studied. This method showed good ruggedness (within 15% C.V.) and was successfully used for the analysis of fenoprofen in human serum samples for the pharmacokinetic studies of orally administered Fenopron tablet (600 mg as fenoprofen) at three different laboratories, demonstrating the suitability of the method.

Biomechanical Efficacy of a Combined Flexible Cage with Pedicle Screws with Spring rods: A Finite Element Analysis (Spring rod를 사용한 척추경 나사못과 동반 시술된 Flexible cage의 생체역학적 효과)

  • Kim, Y.H.;Park, E.Y.;Kim, W.H.;Hwang, S.P.;Park, K.W.;Lee, Sung-Jae
    • Journal of Biomedical Engineering Research
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    • v.38 no.1
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    • pp.9-15
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    • 2017
  • Recently, flexible cages have been introduced in an attempt to absorb and reduce the abnormal load transfer along the anterior parts of the spine. They are designed to be used with the pedicle screw systems to allow some mobility at the index level while containing ROM at the adjacent level. In this study, a finite element (FE) study was performed to assess biomechanical efficacies of the flexible cage when combined with pedicle screws with flexible rods. The post-operated models were constructed by modifying the L4-5 of a previously-validated 3-D FE model of the intact lumbar spine (L2-S1): (1) Type 1, flexible cage only; (2) Type 2, pedicle screws with flexible rods; (3) Type 3, interbody fusion cage plus pedicle screws with rigid rods; (4) Type 4, interbody fusion cage plus Type 2; (5) Type 5, Type 1 plus Type 2. Flexion/extension of 10 Nm with a compressive follower load of 400N was applied. As compared to the Type 3 (62~65%) and Type 4 (59~62%), Type 5 (53~55%) was able to limit the motion at the operated level effectively, despite moderate reduction at the adjacent level. It was also able to shift the load back to the anterior portions of the spine thus relieving excessively high posterior load transfer and to reduce stress on the endplate by absorbing the load with its flexible shape design features. The likelihood of component failure of flexble cage remained less than 30% regardless of loading conditions when combined with pedicle screws with flexible rods. Our study demonstrated that flexible cages when combined with posterior dynamic system may help reduce subsidence of cage and degeneration process at the adjacent levels while effectively providing stability at the operated level.

Development and Validation of an HPLC Method for the Pharmacokinetic Study of Pentoxifylline in Human Serum (체내동태 연구를 위한 혈청 중 펜톡시필린의 HPLC 정량법 개발 및 검증)

  • Cho, Hea-Young;Kang, Hyun-Ah;Yoo, Hee-Doo;Lee, Hwa-Jeong;Moon, Jai-Dong;Lee, Yong-Bok
    • Journal of Pharmaceutical Investigation
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    • v.36 no.2
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    • pp.89-95
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    • 2006
  • A selective and sensitive reversed-phase HPLC method for the determination of pentoxifylline in human serum was developed, validated, and applied to the pharmacokinetic study of pentoxifylline. Pentoxifylline and internal standard, chloramphenicol, were extracted from the serum by liquid-liquid extraction with dichloromethane and analyzed on a Luna CI8(2) column with the mobile phase of acetonitrile-0.034 M phosphoric acid (25:75, v/v, adjusted to pH 4.0 with 10 M NaOH). Detection wavelength of 273 nm and flow rate of 0.8 mL/min were used. This method showed linear response over the concentration range of 10-500 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 0.5 mL of the serum was 10 ng/mL, which was sensitive enough for pharmacokinetic studies of pentoxifylline. The overall accuracy of the quality control samples ranged from 89.3 to 92.7% for pentoxifylline with overall precision (% C.V.) being 4.1-9.2%. The relative mean recovery of pentoxifylline for human serum was 105.8%. Stability (stock solution, short and long-term) studies showed that pentoxifylline was not stable during storage. But three freeze-thaw cycles and extracted serum samples were stable. This method showed good ruggedness (within 15% C.V.) and was successfully applied for the analysis of pentoxifylline in human serum samples for the pharmacokinetic studies of orally administered $Trental^{\circledR}$ tablet (400 mg pentoxifylline), demonstrating the suitability of the method.

A Design for the Symbol Park and the Waterfront Park for the Second Stage Development in the Eastern Rear Complex of Gwangyang Harbor (광양항 동측배후단지 2단계 사업지구 상징공원 및 수변공원 설계)

  • Hong Hyoung-Soon;Kim Do-Kyong;Jeong Han-Ho
    • Journal of the Korean Institute of Landscape Architecture
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    • v.34 no.3 s.116
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    • pp.104-119
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    • 2006
  • The eastern rear business complex of the Gwangyang Harbor (second stage) has undergone the 'alternative bid' process by which a construction company is selected based on their suggestions for an alternative plan and the bid for the construction expenses is based on the previously completed original plan, thereby implicitly accepting the arrangement and scale of the park which was presented in the original plan. It is possible, however, that the concept and plan of each park needs to be approached in a new way within the extent of given design guidelines. This study focuses on the alternative plan process and the Symbol Park (the second neighborhood park) and Waterfront Park (the third neighborhood park) among the five neighborhood parks in the eastern rear business complex (second stage). These two parks provide scale and function for the structure of the park and greenways system at the eastern rear complex. The neighboring waterway is a significant resource for emphasizing the pre-development features of the site. The alternative plan process focuses on determining the resources for the park's plan based on the environmental analyses of the site and utilizing the results. That is, through an analysis of the current state, all available resources are determined and the facilities and activities are derived based on these results. By this, Symbol Park and Waterfront Park reflect the regional features of the eastern rear complex, and these parks will feasibly perform the role of the region's key parte. The limit of this study is the fact that there is no chance for landscape architecture to actively play a role in the creation of the master plan, land utilization plan, and plan for the complex. Therefore there is a problem that the function scale and location of the park are not distributed appropriately in the rear complex. Also the plan for protecting the waterway's shore, a significant resource, only considers the structural stability of the engineering works, degrading the visual and ecological quality. These experiences will be used as a case for further designing the industrial complex and for the resulting park plan.

The Effect of Ankle Balance Training on Unstable and Stable Surface on Proprioception, Balance and Muscle Strength in Obese Middle-Aged Woman (불안정지지면과 안정지지면에서의 발목균형훈련이 비만중년여성의 고유수용성감각, 균형 및 근력에 미치는 영향)

  • Han, Jun Ho;Woo, Sunghee;Lee, Hyojeong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2018.05a
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    • pp.580-583
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    • 2018
  • Purpose: The purpose of this study was to compare the effects of ankle balance training on unstable and stable surfaces to discover on which surface the proprioception, balance and muscle strength of obese middle aged women improves more. Method: 30 obese middle-aged women were randomly recruited and divided into two groups (training on an unstable surface, training on a stable surface). The subjects in each group participated in the training for six weeks, three times per week for 30 minutes each session. Proprioception was measured using Dualer IQ digital inclinometer; sway length (SL) and sway area (SA) of center of pressure, and limit of stability (LOS) were measured for balance; muscle strength before and after the training was measured using manual muscle testing. Results: There were significant improvements in the subscales of the proprioception, balance and muscle strength in those who participated in ankle balance training on the unstable surface, and in those who participated on the stable surface. Therefore, the training of participants on unstable and stable surfaces did not identify which ankle balance training technique was more effective. Conclusion: Unstable and stable surface ankle balance training are both effective in improving the proprioception, balance and muscle strength of obese middle-aged woman.

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Consolidation Behavior of Agricultural Reservoir under Embankment on Soft Ground (연약지반상(軟弱地盤上)에 축조(築造)된 농업용저수지(農業用貯水池) 제체의 압밀거동(壓密擧動))

  • Oh, Beom-Hwan;Lee, Dal-Won;Eam, Sung-Hoon
    • Korean Journal of Agricultural Science
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    • v.29 no.2
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    • pp.53-66
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    • 2002
  • This study was performed to evaluation the consolidation behavior of agricultural reservoir in the very soft ground. The final settlement prediction methods by Terzaghi, Hyperbolic and Asaoka methods were used to compare with the degree of consolidation estimated by exess pore water pressure. The dissipated excess pore water pressure during embankment construction and peak excess pore water pressure on the completed embankment were suggested for the estimation of the degree of consolidation. It was concluded that the degree of consolidation estimated from dissipated excess pore water pressure was more reliable than that from the peak excess pore water pressure. The stability methods for agricultural reservoir was used to compare and analyze with various condition by limit equilibrium method.

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Simultaneous Determination of B Group Vitamins in Supplemented Food Products by High Performance Liquid Chromatography-Diode Array Detection

  • Suh, Joon-Hyuk;Yang, Dong-Hyug;Lee, Byung-Kyu;Eom, Han-Young;Kim, Un-Yong;Kim, Jung-Hyun;Lee, Hye-Yeon;Han, Sang-Beom
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2648-2656
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    • 2011
  • A simple HPLC-DAD method was developed and validated to determine B group vitamin content (thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxine and folic acid) in supplemented food samples, i.e., infant formula, cereal, low-calorie food, a multi-vitamin pill and a vitamin drink. In this study, the most significant advantages were simultaneous determination of the six B group vitamins in various food matrices and a small number of sample treatment steps that required only an organic solvent, acetonitrile. Moreover, this method prevents reduction of column durability, because the mobile phase does not contain ion-pairing reagents. Analytes were separated on a Develosil RPAQUEOUS $C_{30}$ (4.6 mm ${\times}$ 250 mm, 5 ${\mu}M$ particle size) column with a gradient elution of acetonitrile and 20 mM phosphate buffer (pH 3.0) at a flow rate between 0.8 and 1.0 mL/min. Detection was performed at 275 nm, except for that of pantothenic acid (205 nm). The calibration curves for all six vitamins showed good linearity with correlation coefficients ($r^2$) higher than 0.995. The developed method was validated with respect to linearity, intra- and inter-day accuracy and precision, limit of quantification (LOQ), recovery and stability. The method showed good precision and accuracy, with intra- and inter-assay coefficients of variation less than 15% at all concentrations. The recovery was carried out according to the standard addition procedure, with yields ranging from 89.8 to 104.4%. This method was successfully applied to the determination of vitamin B groups in supplemented food products.

Implant placement simultaneously sinus augmentation using crestal approach in severely atrophic maxilla; minimally invasive approach (골 흡수가 심한 상악 구치부에서 치조정 접근법을 이용하여 상악동 골이식술 동시 임플란트 식립)

  • Kim, Hyun-Joo;Kwon, Eun-Young;Choi, Jeomil;Lee, Ju-Youn;Joo, Ji-Young
    • Journal of Dental Rehabilitation and Applied Science
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    • v.33 no.1
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    • pp.47-54
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    • 2017
  • The atrophy of edentulous ridge and pneumatization of the maxillary sinus often limit the volume of bone available for implant placement on maxillary posterior teeth. Most clinicians suffer difficulties from poor bone quality and quantity on maxillary posterior site. Thus, the success of maxillary posterior implant surgery depends on the increase of the available bone and obtaining a good initial stability of the implant after maxillary sinus reconstruction. The maxillary sinus augmentation methods include a crestal approach and a lateral approach. Less morbidity and complications after operation is major advantage to sinus augmentation using crestal approach than lateral approach. However, when the residual ridge height is ${\geq}6mm$, it is known that crestal approach is appropriate. Also delayed implantation after sinus augmentation is recommended in severely atrophic ridge. We present the three cases of implant placement simultaneously sinus augmentation using crestal approach in posterior maxilla site with ${\leq}3mm$ of residual alveolar bone.

The Effects of the Biodiversity Increase after Creation of the Artificial Wetland -The Case of Ecological Pond at Seoul Technical High School- (인공습지 조성후 생물다양성 증진 효과에 관한 연구 -서울공고 생태연못을 중심으로-)

  • 김귀곤;조동길
    • Journal of the Korean Institute of Landscape Architecture
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    • v.27 no.3
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    • pp.1-17
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    • 1999
  • The purpose of this study is to evaluate the creation techniques of artificial wetland, one of biotopes developed to promote biodiversity in urban areas, and to look for improvement steps. Specifically, artificial wetland creation techniques were categorized into living environment and living creature classification. Being living conditions for creations, habitat environment was reviewed with a focus on water and soil environments. Living creatures were classified into plants, insects, fish, and birds. The evaluation of creation techniques was done in post-construction evaluation while considering the creation of habitats for living creatures. Intervention by users, changes in living environment and living species, and relevance of creation techniques were reviewed. Key results of this study are as follows. (1) Water environment for the living environment of creatures provides a suitable environment conditions for the living of creatures through a process easing the use of piped water. Various water depths and embankment appear to have a positive impact on the living of aquatic life. In particular, embankment covered in soil naturally played an important role as a place for the activities of aquatic insects and young fish as well as the growth of aquatic plants. (2) Various aquatic and ground plants to promote insect-diversity, shallow water, and old-tree logs had contributed greatly in increasing the types and number of insects. Aquatic insects. Aquatic insects were seen much particularly in areas where aquatic plants are rich but water is shallow than any other areas. (3) A space piled with stone to provide habitats for fish was not much used. However, it was observed that fish used embankment built with natural stones and embankment using logs in areas where water is deep. In addition, it was confirmed that 1,500 fish that had been released propagated using various depths and places for birth. (4) It was analyzed that techniques (creation of island, log setting, and creation of man-made bird nests) to provide habitats and to attract birds are not serving their roles. In such a case, it is believed that species had not increased due to the smallness as well as isolated features of the area. Based on theoretical review, they are judged to be areas that are likely to be used when a greater variety of birds is introduced. It is judged that attracting and keeping more birds at the site, such spaces need to be linked systematically in the future in terms of building eco-network while ensuring an adequate living areas. (5) In the study areas, users intervened greatly. As a result, a blockage was created preventing the normal growth of plants and non-indigenous plants were introduced. In order to limit the intervention by users, setting enough buffer zones, and environment education programs were urgently required. D/H=1>Hyangkyo> houses on the river>temples>lecture halls. D/H ratio of the backside areas is as follows. D/H=1>Hyangkyo>houses on the river>lecture halls. 4. Inner garden were planted deciduous than evergreen trees with Lagerstroemia indica. Enclosed dominant trees were planted by Pinus densiflora, Querces seuata. construct GEM strain, and examined for the expression and functional stability in microcosms.

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Variation of Landslide Risk with Parameters (매개변수에 따른 산사태 위험도의 변화)

  • Lee, Jundae;Kwon, Youngcheul;Bae, Wooseok
    • Journal of the Korean GEO-environmental Society
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    • v.19 no.1
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    • pp.15-23
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    • 2018
  • In this study we performed risk evaluation based on parameters using the SINMAP, GIS-based extended program in order to predict ground disaster that is frequent recently. As for the risk evaluation, in order to understand the effects of parameters, we defined that the ranges of internal friction angles and T/R values as important variables had three and four patterns, respectively. The results of the interpretation were compared with those of the existing landslide in order to identify landslide flow and to evaluate the applicability of the parameters. The analysis of the geomorphologic saturated zone showed that the boundary saturated zone and the saturated zone were almost consistent with the site of avalanche of earth and rocks and the area of underground water convergence was correlated to the area where collapse started, indicating that the geomorphologic saturated zone may serve as an index for estimating possibility of landslide when used with slope distribution, colluvial soil, and structures inducing landslide in combination. When the lower limit of the internal friction angle increased more, the upper threshold decreased by 50 to 70% and the influence on the stability index was higher, but the influence was declined within the range of lower wetness index. The analysis of changes based on wetness index range showed that all the groups have similar SI distribution, except for the one in which mean altitude values are applied, indicating that the results are susceptible more by the internal friction angle than by the wetness index.