• Journal of Biomedical Engineering Research
• /
• v.43 no.4
• /
• pp.241-250
• /
• 2022

It is known that chronic pain and injury of upper limb joint tissue in manual wheelchair users is usually caused by muscle imbalance, and the propulsion speed is reported to increase this muscle imbalance. In this study, kinematic variables, electromyography, and ultrasonographic images of the upper limb were measured and analyzed at two different propulsion speeds to provide a quantitative basis for the risk of upper extremity joint injury. Eleven patients with spinal cord injury for the experimental group (G_E) and 27 healthy adults for the control group (G_C) participated in this study. Joint angles and electromyography were measured while subjects performed self-selected comfortable and fast-speed wheelchair propulsion. Ultrasound images were recorded before and after each propulsion task to measure the acromiohumeral distance (AHD). The range of motion of the shoulder (14.35 deg in G_E; 20.24 deg in G_C) and elbow (5.25 deg in G_E; 2.57 deg in G_C) joints were significantly decreased (p<0.001). Muscle activation levels of the anterior deltoid, posterior deltoid, biceps brachii, and triceps brachii increased at fast propulsion. Specifically, triceps brachii showed a significant increase in muscle activation at fast propulsion. AHD decreased at fast propulsion. Moreover, the AHD of G_E was already narrowed by about 60% compared to the G_C from the pre-tests. Increased load on wheelchair propulsion, such as fast propulsion, is considered to cause upper limb joint impingement and soft tissue injury due to overuse of the extensor muscles in a narrow joint space. It is expected that the results of this study can be a quantitative and objective basis for training and rehabilitation for manual wheelchair users to prevent joint pain and damage.

• Journal of Aerospace System Engineering
• /
• v.17 no.4
• /
• pp.1-9
• /
• 2023

Recently, as Synthetic Aperture Radar (SAR), communication, and signal surveillance missions of spacecraft have become more advanced, research has been actively conducted on the deployable large mesh antenna system with excellent storage efficiency compared to the deployment area, and light weight. Deployable Mesh antennae are characterized by an increase in the number of Openings Per Inch (OPI), which is a measure of mesh weaving density as the mission frequency band increases, and this OPI change directly affects the thermal optical properties of the mesh antenna, so research on this is required. In this paper, to verify the thermal relationship between the optical properties of the mesh and antenna reflector, thermal sensitivity analysis between the mesh and the antenna reflector is performed by in-orbit thermal analysis with various optical characteristics of the mesh based on existing overseas research cases. In addition, the temperature gradient effect of the mesh reflector is analyzed.

• Tunnel and Underground Space
• /
• v.33 no.4
• /
• pp.244-254
• /
• 2023

The disc cutter mounted on the Tunnel Boring Machine (TBM) is subjected to cutting forces in three dimensions during rock excavation process. It is widely known that the cutting forces increased with the strength of the rock mass, while the rolling force can be significantly increased when the disc cutter encounters abnormal rotation. Therefore, the cutting force acts on the disc cutter provides important information because it represents the conditions of the rock mass and the disc cutter. For these reasons, several studies have been conducted to measure the cutter forces in real-time. This paper introduces the current status of research on the cutter force measurement of TBM disc cutters, which has been reported in the literature. It is judged that this paper can be a useful reference material when similar technologies are developed in Korea in the future.

• Journal of Korean Port Research
• /
• v.11 no.2
• /
• pp.305-320
• /
• 1997

The objective of this paper is to analysis & forecast on the change in spatial structures of southeast region by development of the Seoul-Pusan high-speed Rail. To measure the spatial structures, it was used the method of mean center and standard distance among of centrographic measures as analytical tools. The changes of spatial structures patten over time and space in the southeast region were surveyed using population and employment data of 57 zones. And also, to forecast the spatial structures of the southeast region after opening of the Seoul-Pusan high-speed rail, it was supposed three(3) scenarios which designed using influential area with centering around of the proposed high-speed rail stations. Therefore, the results of this research indicate as follows; 1) The spatial structures of population is showed a trend of continual concentration toward Ulsan city area, and also the spatial structures of employment is showed a trend of continual dispersion over time. 2) The forecast of three93) scenarios supposed after opening of the Seoul-Pusan high-speed rail in 2006 show a change of the spatial structures with both population concentration and employment dispersion. In the meantime, the rapid increase of population and wide dispersion of employment is reform with centering around HSR stations which builted in the southeast region after opening of high-speed rail. 3) It shall furnish valuable data to establish the development strategy of urban and local region, and also forecast the change of spatial structures about population and employment in influential area which passed on high-speed rail line & stations by method of mean center and standard distance among of centrographic measures as analytical tools.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.2
• /
• pp.15-28
• /
• 2023

Boundary Station is an evaluation index that was not reflected in the Seoul Metropolitan Urban Railroad Connected Eare Allocation. Boundary station is a station located at the boundary point of two transportation agencies sharing the same route, and track operation methods are divided into business management and maintenance management. Until now, the Connected Fare Allocation has evaluated the boundary stations from the perspective of business management. Meanwhile, the integrated public transportation fee system requires the need to interpret the boundary stations from the point of view of maintenance management at the developmental level. This study was prepared a measure to quantitatively analyze changes in income with the introduction of maintenance methods in mind. The Change in the income of operation agency evaluated based on the daily transportation card data for the boundary stations of the four Seoul Transportation Corporation and KORAIL sections. This study is meaningful as a basic research for an analytical judgment that evaluates and allocates changes in transportation income of Seoul Metropolitan Urban Railroad in the future.

• Publications of The Korean Astronomical Society
• /
• v.38 no.1
• /
• pp.1-12
• /
• 2023

Numerous Sundials were fabricated during the reign of King Sejong of the Joseon Dynasty. One among them is Jeongnam-Ilgu (the Fixing-South Sundial), where the time can be measured after setting up the suitable meridian line without a compass. We reconstructed the new Jeongnam-Ilgu model based on the records of 'Description of Making the Royal Observatory Ganui (簡儀臺記)' in the Veritable Record of King Sejong. Jeongnam-Ilgu has a summer solstice half-ring under a horizontal ring which is fixed to two pillars in the north and south, and in which a declination ring rotates around the polar axis. In our model, the polar axis matches the altitude of Hanyang (that is Seoul). There are two merits if the model is designed to install the polar axis in the way that enters both the north and south poles and rotates in them: One is that it is possible to fix the polar axis to the declination ring together with the cross-strut. The other is that a twig for hanging weights can be protruded on the North Pole. The declination ring is supposed to be 178 mm in diameter and is carved on the scale of the celestial-circumference degrees on the ring's surface, where a degree scale can be divided into four equal parts through the diagonal lines. In addition, the time's graduation that is drawn on the summer solstice half-ring makes it possible to measure the daytime throughout the year. An observational property of Jeongnam-Ilgu is that a solar image can be obtained using a pin-hole. The position cast by the solar image between hour circles makes a time measurement. We hope our study will contribute to the restoration of Jeongnam-Ilgu.

• Restorative Dentistry and Endodontics
• /
• v.46 no.1
• /
• pp.13.1-13.9
• /
• 2021

Objectives: This study aimed to evaluate and compare the efficacy of the S1 reciprocating system and the D-Race retreatment rotary system for filling material removal and the apical extrusion of debris. Materials and Methods: Sixty-four freshly extracted maxillary canines were shaped with size 10 and size 15 K-files, instrumented using ProTaper Gold under irrigation with 2.5% sodium hypochlorite (NaOCl), obturated according to the principle of thermo-mechanical condensation with gutta-percha and zinc oxide eugenol sealer, and allowed to set for 3 weeks at 37℃. Subsequently, the teeth were divided into a control group (n = 4), the D-Race rotary instrument group (n = 30), and the S1 reciprocating instrument group (n = 30). After classical retreatment, the canals were subjected to a complementary approach with the XP-Endo Shaper. Desocclusol was used as a solvent, and irrigation with 2.5% NaOCl was performed. Each group was divided into subgroups according to the timing of radiographic readings. The images were imported into a software program to measure the remaining filling material, the apical extrusion, and the root canal space. The data were statistically analyzed using the Z-test and JASP graphics software. Results: No significant differences were found between the D-Race and S1 groups for primary retreatment; however, using a complementary cleaning method increased the removal of remnant filling (p < 0.05). Conclusions: Classical removal of canal filling material may not be sufficient for root canal disinfection, although a complementary finishing approach improved the results. Nevertheless, all systems left some debris and caused apical extrusion.

• The korean journal of orthodontics
• /
• v.53 no.4
• /
• pp.254-263
• /
• 2023

Objective: The evidence on the accuracy of bite registration using intraoral scanners is sparse. This study aimed to develop a new method for evaluating bite registration accuracy using intraoral scanners. Methods: Two different types of models were used; 10 stone models and 10 with acrylic resin teeth. A triangular frame with cylindrical posts at each apex (one anterior and two posteriors) was digitally designed and manufactured using three-dimensional (3D) printing. Such a structure was fitted in the lingual space of each maxillary and mandibular model so that, in occlusion, the posts would contact their opposing counterparts, enforcing a small interocclusal gap between the two arches. This ensured no tooth interference and full contact between opposing posts. Bite registration accuracy was evaluated by measuring the distance between opposing posts, with small values indicating high-accuracy. Three intraoral scanners were used: Medit i500, Primescan, and Trios 4. Viewbox software was used to measure the distance between opposing posts and compute roll and pitch. Results: The average maximum error in interocclusal registration exceeded 50 ㎛. Roll and pitch orientation errors ranged above 0.1 degrees, implying an additional interocclusal error of around 40 ㎛ or more. The models with acrylic teeth exhibited higher errors. Conclusions: A method that avoids the need for reference hardware and the imprecision of locating reference points on tooth surfaces, and offers simplicity in the assessment of bite registration with an intraoral scanner, was developed. These results suggest that intraoral scanners may exhibit clinically significant errors in reproducing the interocclusal relationships.

• Journal of English Language & Literature
• /
• v.55 no.1
• /
• pp.177-198
• /
• 2009

How are we approach the fourteenth chapter of Ulysses known as 'The Oxen of the Sun' in this globalized age of hyper-theorization? My paper argues that examining the wide reverberations set off by Derrida's comment in "Ulysses Gramophone"-"Everything has already happened to us with Ulysses"-in relation to the central textual theme of cosmopolitanism may provide a reading that not only pays due respect to the critical legacy of the early structuralist interpretations but equally takes into account the political sensibilities of our time. The neologism 'chaosmopolitanism,'in fact, serves as that very critical measure designed to bridge the gap separating the long tradition of Western Eurocentric discourse on cosmopolitanism on the one hand and the geopolitical background conditioning its discursive possibility, namely, the chaotic condition of international colonialism on the other, whose exemplary, and exemplarily creative, fusion bears none other name than Ulysses. But the idea of chaosmopolitanism gains its conceptual leverage on yet another, no less pivotal register, for, just as with Derrida's first-person plural pronoun, the trope leads us to reflect on our own situatedness in the East Asian region in light of Joyce's unabashedly universalist vision, whose over-arching textual purview nonetheless leaves the space called the Far East in the singular position of virtual exclusion. What does it then mean to enjoy Joyce's "chaffering allincluding most farraginous chronicle" in light of our East Asian perspective? To this second question, my inquiry turns to the dual theme of enjoyment and debt as they are problematized by Stephen Dedalus' telegram to Mulligan, which reads, "the sentimentalist is he who would enjoy without incurring the immense debtorship for a thing done." Itself a quotation from George Meredith's novel The Ordeal of Richard Feverel, the transcribed message invites us to reconsider the scrupulous endeavor underwriting Joyce's signatory gusto, but at the same time forcing us to confront and reassess our own debt to the problematic heritage known as Western literature or, to borrow Derrida's expression, Abrahamic language.

• Tunnel and Underground Space
• /
• v.33 no.5
• /
• pp.425-434
• /
• 2023

To measure the wear amount of the TBM disk cutter in real time, it is important not only to automate the measurement using sensors, but also to stably transmit the measured data to the information processing system. In this study, we investigated the viability of utilizing Bluetooth Low Energy (BLE) technology to wirelessly transmit sensor data from the TBM cutter head to a receiver located at the chamber's rear. Through laboratory experiments, we analyzed the Received Signal Strength Index (RSSI) of the receiver considering various signal strength of the transmitter, separation distances between the transmitter and receiver and chamber fill materials. Our results demonstrate that wireless data transmission is feasible across all tested conditions when the transmitter signal strength is 0 dBm or higher.