• Structural Engineering and Mechanics
• /
• v.42 no.2
• /
• pp.191-210
• /
• 2012

The Force Density Method (FDM) is a well known and extremely versatile tool in form finding of cable nets. In its linear formulation such method makes it possible to find all the possible equilibrium configurations of a net of cables having a certain given connectivity and given boundary conditions on the nodes. Each singular configuration corresponds to an assumed force density distribution. Its improvement as Non-Linear Force Density Method (NLFDM) introduces the possibility of imposing assigned relative distances among the nodes, the tensile level in the elements and/or their initial undeformed length. In this paper an Extended Force Density Method (EFDM) is proposed, which makes it possible to set conditions in terms of given fixed nodal reactions or, in other words, to fix the positions of a certain number of nodes and, at the same time, to impose the intensity of the reaction force. Through such extension, the (EFDM) enables us to deal with form findings problems of cable nets subjected to given constraints and, in particular, with mixed structures, made of cables and struts. The efficiency and the robustness of method are assessed through comparisons with other form finding techniques in dealing with characteristic applications to the prestress design of cable systems. As a further extension, the EFDM is applied to structures having some parts not yet geometrically defined, as can happen in designing new creative forms.

• Korean Journal of Applied Biomechanics
• /
• v.26 no.1
• /
• pp.83-92
• /
• 2016

Objective: This study aimed to compare differences in biomechanical factors according to distance changes in relation to approaches during a round of golf to obtain basic data on golf swings. Methods: The research subjects were 8 KPGA-affiliated professional golfers who performed approach shots that put a ball into a circle of 8 feet in diameter from distances of 30, 50, and 70 m. Data were collected by using six infrared cameras and a ground reaction force device, which were applied to calculate biomechanical factors by using Kwon3D XP. The calculated data were subjected to one-way ANOVA by using SPSS 20.0, with the significance level set at p value of 0.05. Results: Elapsed time, stance width, clubhead position variation, clubhead synthesis speed, and cocking angle significantly differed according to distance change during the approach swing. Clubhead speed was positively related with stance width and clubhead displacement. Ground reaction force significantly differed according to distance change during the approach swing. Factors before and after showed differences in other states, except in the impact state. Conclusion: In the present study, we drew several conclusions regarding biomechanical factors and ground reaction forces according to distance change in the approach swing of professional golfers. According to these conclusions, we suggest that distance control with swing range is more important than power control in maintaining the accuracy and consistency of golf swing and is the most important mechanism of golf swing.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.4 s.247
• /
• pp.457-464
• /
• 2006

The anterior cruciate ligament (ACL) is liable to a major injury that often results in a functional impairment requiring surgical reconstruction. The success of reconstruction depends on such factors as attachment positions, initial tension of ligament and surgical methods of fixation. The purpose of this study is to find isometric positions of the substitute during flexion/extension. The distance between selected attachments on the femur and tibia was computed from a set of measurements using a 6 degree-of-freedom magnetic sensor system. A three-dimensional knee model was constructed from CT images and was used to simulate length change during knee flexion/extension. This model was scaled for each subject. Twenty seven points on the tibia model and forty two points on the femur model were selected to calculate length change. This study determined the maximum and minimum distances to the tibial attachment during flexion/extension. The results showed that minimum length changes were $1.9{\sim}5.8mm$ (average $3.6{\pm}1.4mm$). The most isometric region was both the posterosuperior and anterior-diagonal areas from the over-the-top. The proposed method can be utilized and applied to an optimal reconstruction of ACL deficient knees.

• Health Policy and Management
• /
• v.25 no.2
• /
• pp.118-128
• /
• 2015

Background: We measured productivity changes of regional public hospitals using both global Malmquist productivity index-based on global production possibility set over all the periods-and the traditional Malmquist productivity index and analyzed the factors of productivity change. Methods: The data used in this study is two annual inputs and two annual outputs of 32 regional public hospitals in Korea from 2005 to 2009 and the results such as distances and Malmquist productivity index and global Malmquist productivity index are obtained by an R program written for this study. Results: The results can be summarized as follows. Firstly, technical efficiencies of regional public hospitals are affected largely by scale efficiency than pure technical efficiency. Second, productivity progressed and technological change has more significant influence on productivity advance over the period between 2005 and 2009. Third, the circularity problem of the traditional Malmquist index is confirmed, and so the global Malmquist index without this problem are valid for the analysis. Conclusion: Though this study also has some limitations with the data of regional public hospitals with a short time span, it is the first study of hospitals using global Malmquist productivity index and later it can be expanded to private hospitals and longer time periods.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.25 no.4
• /
• pp.179-189
• /
• 2021

Conditional spectra (CS) are applied to the seismic fragility assessment of a nuclear power plant (NPP) containment building for comparison with a relevant conventional uniform hazard response spectrum (UHRS). Three different control frequencies are considered in developing conditional spectra. The contribution of diverse magnitudes and epicentral distances is identified from deaggregation for the UHRS at a control frequency and incorporated into the conditional spectra. A total of 30 ground motion records are selected and scaled to simulate the probability distribution of each conditional spectra, respectively. A set of lumped mass stick models for the containment building are built considering nonlinear bending and shear deformation and uncertainty in modeling parameters using the Latin hypercube sampling technique. Incremental dynamic analysis is conducted for different seismic input models in order to estimate seismic fragility functions. The seismic fragility functions and high confidence of low probability of failure (HCLPF) are calculated for different seismic input models and analyzed comparatively.

• Journal of Positioning, Navigation, and Timing
• /
• v.13 no.1
• /
• pp.103-110
• /
• 2024

In this paper, a test bed for real-time network Real-Time Kinematic (RTK) research was constructed using reference stations of the NGII. A group of candidate station networks was derived, including three stations in Seoul. The group consisted of four stations with a distance of less than 100 km between them. Among several candidates, a network composed of stations with short distances between them and demonstrating good data quality for all reference stations was selected as the test bed. After collecting real-time data in Radio Technical Committee for Maritime services (RTCM) format from the selected stations and conducting a noise analysis on measurements, mm-level carrier phase measurement noise was confirmed. Afterwards, the user set the reference station inside the test bed and analyzed the network RTK positioning performance of the MAC method using the GPS L1 frequency as post-processing. From the result of the analysis it was confirmed that the residual error for all users was within 10 cm after applying the correction. Additionally, after determining integer ambiguities through Least-squares AMBiguity Decorrelation Adjustment (LAMBDA), it was confirmed that the fix rate was 100%, and all ambiguities were resolved as true values.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2008.10a
• /
• pp.106-109
• /
• 2008

The aim of this study is to develop a model of layering system for future soldier system. Future soldier has been supposed to carry various digital devices embedded into the combat uniform. The combat uniform must be developed to be fit to soldier's body and movement, and can be felt comfortable to soldier. The Uniform must be studied in ergonomic and physiological component because it is different from the present one. It has many devices inside, so there are some unknown barriers to set the devices on to the body. For making the ergonomic aspect of future combat suits clear, the movement of the body was researched. The size of arms(3 parts), torsos(4 parts), and legs(3 parts) of people were measured by movement. Many dots were drawn on the testees' bodies every 3cm. Each time they made compulsory poses, the distances between dots be measured and analyzed. For making the physiological aspect of future combat suits clear, the thermo-map and sweating map of body were made. The 3 maps - movement, thermo and sweating- were overlapped. The devices for future soldier were arranged on the overlapped map considering relations between devices. The final layering system developed on the arrangement of devices.

• Development and Reproduction
• /
• v.26 no.2
• /
• pp.91-98
• /
• 2022

Genomic DNA (gDNA) set apart from two populations of Korean Charybdis crab (Charybdis japonica) was augmented by PCR experiments. The five oligonucleotides primers (ONT-primers) were spent to yield the number of unique loci shared to each crab population (ULSECP) and number of loci shared by the two crab populations (LSTCP). 305 fragments (FRAGs) were identified in the Charybdis crab population A (CCPA), and 344 in the Charybdis crab population B (CCPB): 44 number of ULSECP (14.43%) in the CCPA and 110 (31.98%) in the CCPB. 44 number of LSTCP, with an average of 8.8 per primer, were detected in the two crab populations. The bandsharing (BS) value between entity's no. 01 and no. 10 was the lowest (0.371) between the two CCPs. The average bandsharing (ABS) values of individuals in the CCPA (0.575±0.014) were lesser than in those originated from the CCPB (0.705±0.011) (p < 0.05). The polar hierarchical dendrogram (PHD) achieved by the five ONT-primers denotes three genetic clusters (GCs): cluster I (CHARYBCRAB 01, 04, 05, 06, and 08), cluster II (CHARYBCRAB 02, 03, 07, 09, 10, and 11) and cluster III (CHARYBCRAB 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and 22). The shortest genetic distance (GD) displaying significant molecular difference (MD) was between individuals CHARYBCRAB no. 18 and CHARYBCRAB no. 17 (0.055).

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.6
• /
• pp.793-799
• /
• 2014

EO GRD(Ground Resolved Distance) resolution of airborne EO/IR(Electro-Optical/Infrared) sensor is a critical factor in test and evaluation for EO sensor performance. We propose the laboratory measurement set-up for EO GRD by constructing optical collimator which includes integrated sphere, blackbody, equivalent 3-bar target and 6 DOF motion simulator. GRD is measured in the photographic imagery of bar targets by 3 different distances for 3 EO/IR sensors and the measured results were analyzed statistically. We found that at least 7 sheets of imagery are needed in order to obtain meaningful EO GRD. The result of statistical analysis shows that the distribution of the measured GRD is nearly symmetric about the average GRD, and the better imagery ratio above the average GRD is about 40~70%. Also from the best GRD analysis, it is estimated that the design goal for EO GRD should be 30% superior to the required GRD.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.3
• /
• pp.91-98
• /
• 2015

As one of solutions to obtain efficient use of limited spectrum resource, we suggest a methodology for the co-channel multi-site radar operations with a shifted linear frequency modulation (SLFM) based on GPS clock. The proposed algorithm is that we find a candidate set of SLFM signals with the minimum acceptable level of the correlation from the cross-correlation characteristics among selected SLFM signals. To verify the proposed methodology, numerical analysis has been accomplished for several radars operating in the same channel with a sawtooth or triangle LFM signal. The computational results of detected distances as well as range profiles are also examined for interference, noise, and algorithm limitation including the error of clock synchronization.