• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.711-722
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• 2011

Beam-column gravity or Intermediate Moment frames subjected to unexpected large displacements are vulnerable when no seismic details are provided, which is typical. Conversely, economic efficiency of those frames is decreased if unnecessary special detailing is applied as the beam and column size becomes quite large and steel congestion is caused by joint transverse reinforcement in beam-column connections. Moderate seismic design is used in Korea for beam-column connections of buildings with structural walls, which are to be destroyed when the unexpected large earthquake occurs. Nonetheless, performance of such beamcolumn connections may be substantially improved by the addition of steel fibers. This study was conducted to investigate the effect of steel fibers in reinforced concrete exterior beam-column connections and possibility for the replacement of some joint transverse reinforcement. Ten half-scale beam-column connections with non-seismic details were tested under cyclic loads with two cycles at each drift up to 19 cycles. Main test parameters used were the volume ratio of steel fibers (0%, 1%, 1.5%) and joint transverse reinforcement amount. The test results show that maximum capacity, energy dissipation capacity, shear strength and bond condition are improved with the application of steel fibers to substitute transverse reinforcement of beam-column connections. Furthermore, several shear strength equations for exterior connections were examined, including the proposed equation for steel fiber-reinforced concrete exterior connections with non-seismic details.

• The korean journal of orthodontics
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• v.36 no.6
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• pp.412-421
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• 2006

Objective: The result of finite element analysis depends on material properties, structural expression, density of element, and boundar or loading conditions. To represent proper elastic behavior, a finite element model was made using Hounsfield unit (HU) values in CT images. Methods: A 13 year 6 month old male was used as the subject. A 3 dimensional visualizing program, Mimics, was used to build a 3D object from the DICOM file which was acquired from the CT images. Model 1 was established by giving 24 material properties according to HU. Model 2 was constructed by the conventional method which provides 2 material properties. Protraction force of 500g was applied at a 45 degree downward angle from Frankfort horizontal (FH) plane. Results: Model 1 showed a more flexible response on the first premolar region which had more forward and downward movement of the maxillary anterior segment. Maxilla was bent on the sagittal plane and frontal plane. Model 2 revealed less movement in all directions. It moved downward on the anterior part and upward on the posterior part, which is clockwise rotation of the maxilla. Conclusion: These results signify that different outcomes of finite element analysis can occur according to the given material properties and it is recommended to use HU values for more accurate results.

• Journal of the Korean GEO-environmental Society
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• v.20 no.6
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• pp.5-13
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• 2019

The international trend in soil nailed wall design has been evolved from the allowable stress design to limit state design and it is still currently ongoing. The design guidelines in Korea and Hong Kong still adopts the allowable stress design philosophy while those in others mostly do the limit state design. In this study, four soil nail design methods presented in the major design guidelines (U.S. FHWA GEC 7 (2015), Clouterre in France (1991), Soil nailing - best practice guidance in U.K. (CIRIA, 2005), Geoguide 7 in Hong Kong (2008) and Design standard for slope reinforcement work in Korea (KDS 11 70 15 f: 2016)) are described and analyzed in brief. The factor of safety and CDR (Capacity-to-Demand Ratio) which is used to measure the degree of conservatism of a design guide are obtained for the two cases. One is the design example presented in CIRIA (2005) and the other is in-situ loading test performed on the top of backfill of the soil nail wall to investigate the conservatism of design guidelines. It is revealed that the design method in overall stability of soil nail walls in domestic design method (CDR=0.78) is the most conservative and those by Clouterre (CDR=0.99, 1.09), Geoguide 7 (CDR=1.13, 0.97), U.S. FHWA (CDR=1.09, 1.07) and CIRIA (CDR=1.40, 1.16) in order from the second most conservative to the least conservative for the design example presented in CIRIA. For the in-situ loading test performed on the top of backfill of the soil nail wall, the order of conservatism is identical except that the places of Geoguide 7 (CDR=0.66, 0.72) and FHWA (CDR=0.73, 0.72) are changed. However, the results obtained among U.S. FHWA (2015) and Clouterre (1991) and Geoguide 7 (2008) are not so different.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.2
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• pp.143-149
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• 2009

Purpose: It is not known whether bone scan is useful for the prediction of the prognosis of patients with temporomandibular disorders(TMD). The aim of the present study was to identify useful prognostic markers on bone scan for the pre-therapeutic assessment of patients with unilateral TMD. Materials and Methods: Between January 2005 and July 2007, 55 patients(M:F=9:46; mean age, $34.7{\pm}14.1$ y) with unilateral TMD that underwent a pre-therapeutic bone scan were enrolled. Uptake of Tc-99m HDP in each temporomandibular joint(TMI) was quantitated using a $13{\times}13$ pixel-square region-of-interest over TMJ and parietal skull area as background. TMJ uptake ratios and asymmetric indices were calculated. TMD patients were classified as improved or not improved and the bone scan findings associated with each group were investigated. Results: Forty-six patients were improved, whereas 9 patients were not improved. There was no significant difference between the two groups of patients regarding the TMJ uptake ratio of the involved joint, the TMJ uptake ratio of the non-involved joint, and the asymmetric index(p>0.05). However, in a subgroup analysis, the patients with an increased uptake of Tc-99m HDP at the disease-involved TMJ, by visual assessment, could be easily identified by the asymmetric index; the patients that improved had a higher asymmetric index than the patients that did not improve($1.32{\pm}0.35$ vs. $1.08{\pm}0.04$, p=0.023), Conclusion: The Tc-99m HDP bone scan may help predict the prognosis of patients with unilateral TMD after splint therapy when the TMD-involved joint reveals increased uptake by visual assessment.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.44-47
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• 2013

Purpose: There are several methods of measuring SUV in PET/CT imaging including $SUV_{bw}$ which uses the body weight, $SUV_{bsa}$ which that uses body surface area and $SUV_{lbm}$ which uses lean body mass. Currently, Seoul National University Hospital uses $SUV_{bw}$ method which minimizes the variability. In this study, we compared and analyzed the correlation between $SUV_{bw}$ and $SUV_{bsa}$ according to patients' body mass index. Materials and Methods: Using Biograph mCT40 (Siemens, Germany), we conducted $^{18}F-FDG$ PET/CT imaging on 70 patients (41 males, 29 females; ages $58.04{\pm}12.44$). We classified the patients as underweight (BMI<20), normal weight (20$${\leq_-}$$BMI<25), overweight (25$${\leq_-}$$BMI<30), obese (30$${\leq_-}$$BMI<35) and severely obese (35$${\leq_-}$$BMI) according to the patient's sex, age and BIM. Then, bone, liver and lungs were set as ROI for calculation of maximum values of $SUV_{bw}$ and $SUV_{bsa}$, through Syngo.via VA11A analysis program. Results: Comparing the five groups divided according to the BMI by the standard differences between $SUV_{bw}$ to $SUV_{bsa}$, $SUV_{max}$ was measured to be $0.66{\pm}0.15$, $0.78{\pm}0.35$, $0.77{\pm}0.21$, $1.00{\pm}0.44$, $1.53{\pm}0.38$ for bones in underweight, normal weight, overweight, obese and severely obese groups, respectively. For liver, values of $SUV_{max}$ were $1.64{\pm}0.16$, $2.06{\pm}0.34$, $2.19{\pm}0.21$, $2.52{\pm}0.21$ and $2.74{\pm}0.40$ in the same order. And for lung, values of $SUV_{max}$ were $0.69{\pm}0.33$, $0.54{\pm}0.17$, $0.62{\pm}0.23$, $0.83{\pm0.29}$, $1.03{\pm}0.30$. Conclusion: By comparing and analyzing the differences between $SUV_{bw}$ and $SUV_{bsa}$ in this study, it was found that the differences between $SUV_{bw}$ and $SUV_{bsa}$ increased as patient's BMI increased. Thus, there is room for error in the values of SUV depending on the methods of calculations, and appropriate methods must be applied according to the circumstances in clinical settings.

• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.368-380
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• 1999

Purpose: The purpose of this study was to evaluate and compare the scintigraphic findings and diagnostic accuracy of double-phase Tc-99m sestamibi scan in primary and secondary hyperparathyroidism (HPT). Materials and Methods: We retrospectively reviewed 16 cases of primary (18 lesions) and 11 cases of secondary HPT (44 lesions) who underwent Tc-99m-sestamibi scan before the surgical intervention. Scan was performed using LEM camera (Siemens, Germany) after the injection of 740MBq of Tc-99m sestamibi. Routine image consisted of baseline and 3-hour delayed images and each image was obtained using both parallel and pine hole collimator. The study population was 27 patients (male/female=5/22, age: $49.1{\pm}10.8$). Results: Eighteen lesions of primary HPT consisted of 13 adenomas and S hyperplasias, while all lesions of secondary HPT were hyperplasias. Among the case of primary HPT, we could detect all the lesions of 13 adenomas but only 2 lesions of 5 hyperplasias (40%) could be detected by double phase scintigraphy. Three cases of primary lesion showed decreased uptake in delayed images compared with baseline. The sensitivity, specificity, positive predictive value and accuracy of primary and secondary HPT were 58.8% (10/17), 83.3% (10/12), 83.3% (10/12), 75.9% (22/29), and 37.5% (15/40), 50% (2/4), 88.2% (15/17), 38.6% (17/44), respectively. Overall sensitivity, specificity, positive predictive value and accuracy were 43.9% (25/57), 75% (12/16), 86.2% (25/29), and 53.4% (39/73). There were no statistical difference between the weight of primary and secondary HPT lesion (p>0.05). Conclusion: Tc-99m sestamibi scan is fairly good modality to detect parathyroid lesion in patient with primary HPT before the surgical intervention. However, since some of cases may reveal decreased uptake in delayed image, a careful attention to the findings of baseline images may be helpful. Still the low accuracy of sestamibi scan in diagnosis of secondary HPT prohibits routine use of it for this disease.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.195-202
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• 1999

Purpose : We peformed this study to evaluate the prognostic factors and the effect of induction chemotherapy in locally advanced non-small cell lung cancer (NSCLC). Materials and Methods : A retrospective analysis was done for 130 patients with locally advanced NSCLC treated with curative radiotherapy alone or induction chemo-radiotherapy from January 1986 to October 1996. Eighty-five patients were treated with radiotherapy alone, forty-five with induction chemotherapy and radiotherapy. Age, sex, performance status, histopathologic type, and stage were evenly distributed in both groups. The patients were treated with 6 MV or 10 MV X-ray. Conventional fractionation with daily fraction size 1$.8\~2.0$ Gy was done. Of the patients, 129 patients received total dose above 59.6 Gy ($56\~66$ Gy, median 60 Gy). Induction chemotherapy regimen were CAP (Cyclo-phosphamide, Adriamycin, Cisplatin) in 6 patients, MVP (Mitomycin, Vinblastine, Cisplatin) in 9 patients, MIC (Mitomycin, Ifosfamide Cisplatin) in 13 patients, and EP (Etoposide, Cisplatin) in 17 patients. Chemotherapy was done in $2\~5$ cycles (median 2). Results : Overall 1-, 2-, and 3-year survival rate (YSR) for all patients were $41.5\%,{\;}13.7\%,{\;}and{\;}7\%$, respectively (median survival time 11 months). According to treatment modality, median survival time, overall 1-, 2-, and 3-YSR were 9 months, $32.9\%,{\;}10.\5%,{\;}6\%$ for radiotherapy alone group, and 14 months, $57.8\%,{\;}20\%,{\;}7.6\%$ for induction chemotherapy group, respectively (f=0.0005). Complete response (CR) to overall treatments was $25\%$ (21/84) in radiotherapy alone and $40.5\%$ (17/42) in induction chemotherapy group (p=0.09). The Prognostic factors affecting overall survival were hemoglobin level (p=0.04), NSE (neuron-specific enolase) level (p=0.004), and respense to overall treatment(p=0.004). According to treatment modalities, NSE (neuron-specific enolase) (p=0.006) and response to overall treatment (p=0.003) were associated with overall survival in radiotherapy alone group, and response to overall treatment (p=0.007) in induction chemotherapy group. The failure Pattern analysis revealed no significant difference between treatment modalities. But, in patients with CR to overall treatment, distant metastasis were found in 11/19 patients with radiotherapy alone, and 3/13 patients with induction chemotherapy and radiotherapy (p=0.07). Locoregional failure patterns were not different between two groups (10/19 vs 6/13). Conclusion : Induction chemotherapy and radiotherapy achieved increased 2YSR compared to radiotherapy alone, At least in CR patients, there was decreased tendency in distant metastasis with induction chemotherapy. But, locoregional failures and long-term survival were not improved. Thus, there is need of more effort to increasing local control and further decreasing distant metastasis.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.759-769
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• 2013

Electronic equipment has been applied to virtually every area associated with commercial, industrial, and military applications. Specifically, electronics have been incorporated into avionics components installed in aircraft. This equipment is exposed to dynamic loads such as vibration, shock, and acceleration. Especially, avionics components installed in a helicopter are subjected to simultaneous sine and random base excitations. These are denoted as sine on random vibrations according to MIL-STD-810F, Method 514.5. In the past, isolators have been applied to avionics components to reduce vibration and shock. However, an isolator applied to an avionics component installed in a helicopter can amplify the vibration magnitude, and damage the chassis, circuit card assembly, and the isolator itself via resonance at low-frequency sinusoidal vibrations. The objective of this study is to investigate the dynamic characteristics of an avionics component installed in a helicopter and the structural dynamic modification of its tray plate without an isolator using both a finite element analysis and experiments. The structure is optimized by dynamic loads that are selected by comparing the vibration, shock, and acceleration loads using vibration and shock response spectra. A finite element model(FEM) was constructed using a simplified geometry and valid element types that reflect the dynamic characteristics. The FEM was verified by an experimental modal analysis. Design parameters were extracted and selected to modify the structural dynamics using topology optimization, and design of experiments(DOE). A prototype of a modified model was constructed and its feasibility was evaluated using an FEM and a performance test.

• 한국해양학회지
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• v.28 no.1
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• pp.1-16
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• 1993

The monthly mean sea levels at 48 stations located at the East and Yellow Seas coasts of Korea, Russia and Japan are processed to investigate seasonal sea level variations. The strong seasonal variations are found to be at the west coast of Korea (42.1 cm in Kunsan), in the region of the Korea strait and near the southern part of Primorye (30-33 cm); the weak ones near the southwestern coast of the Sakhalin Island (10-12 cm). Practically for the whole study area except the southwest Sakhalin, the general picture of the seasonal sea level changes is alike: the mean sea level rises in summer-autumn and falls in winter-spring. The spectral analysis of the records also shows that the seasonal oscillations strongly dominate in the sea level variations, more than 80% or total energy in the southern part of the investigated region and 50-70% in the northern part relate to these oscillations. The annal peak significantly prevails in spectra of the monthly sea levels for the majority of stations, the semiannual peak is also well manifested, but the seasonal peaks of higher order (corresponding to the periods of four and three months) reveal only at some records. The maximal amplitudes of annual component by a least square method are found at the Yellow Sea coast of Korea (20-21 cm) and also near the Japanese coast of the korea Strait (19-19 cm). The semiannual component has the maximal amplitudes (3-4 cm) near the south and southwestern coasts of the Sakhalin Island. The annual range of the sea levels is much weaker here than in the other regions, the relative investment of the seasonal oscillations in total energetic budget is only 35-40%, annual ($A_1$) and semiannual ($A_2$) components have nearly the same amplitude (seasonal factor $F=A_1/A_2=0.9-1.2$). On the basis of the present examination on sea level changes together with the results of Tomizawa et. al.(1984) the whole investigated area may be divided into 10 subregions, 2 of them are related to the Yellow Sea and Western part of the Korea Strait (Y1, Y2), the other ones (E1-E8) to the East Sea.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.179-188
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• 1994

This study was conducted to investigate the distribution of potassium fractions and to establish the soil chemical indices for assessing potassium availability in upland soil. Soil samples were collected from 66 vegetable crop fields of Chungbuk Jungweon, Jeonbuk Imsil and Kyengbuk Euiseong and these samples were analyzed water soluble(W. S. -K), exchangeable(Exch. -K) and nonexchangeable potassium(Nonex. -K). The distribution of potassium fractions was examined for soils having different physico-chemical properties and compared with the soil parameters related to the potassium availability. 1. The distribution ranges of W.S.-K, Exch.-K and Nonex.-K were 0.07~1.42, 0.27~2.30, and 0.84~4.74me/100g, and average contents of relevent fractions were 0.40, 1.03 and 2.37me/100g respectively. 2. Contents of W.S.-K and Exch.-K were decreased with increasing soil pH, CEC, Exch. Ca and Exch. Mg contents but Nonex. -K showed a low correlationship with these factors. 3. Exch.-K content slightly inereased with increasing clay content, while W.S.-K and Nonex. -K contents were grandually decreased with clay contents. 4. The relationship between W.S.-K and Exch.-K was significant and W.S.-K was released from soil at 0.23me/100g content of Exch.-K 5. Contents of W.S-K and Exch.-K showed high correlationship with soil chemical parameters such as ratio of exchangeable cations(K/Ca+Mg), ratio of exchangeable cation equivalent[$K/{\sqrt{Ca+Mg}}:(me/100g)^{1/2}$], potassium exchangeable free energy(${\Delta}F=RT$ 1n $K/{\sqrt{Ca+Mg}}$ : calories/mole) and saturation percentage of potassium($Exch.K/CEC{\times}100$), and these factors were considered to be good parameters for assessing soil potassium availability.