• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.189-196
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• 1991

The purpose of this study was to observe the inital acidity of zinc phosphate cements(Confit and Super Cem), poly carboxylate cement(Unident and Poly F), zinc oxide engenol cement(Stailine Super EBA) and g1ass ionomer cement(Fuji ionomer) Each cement was manuplated in accordance with each manufacturer's direction. All cements were mixed at the room temperature of $23^{\circ}{\pm}$, $5^{\circ}C$, and the electrode of pH meter(Ionanalyzer) was inserted in the mixed cement, and the acidity of cement were measured for 20 minutes from begining of cement mixing at $23^{\circ}C$ and $37^{\circ}C$ Results were as follows 1. The acidity of all cements ranges from pH 3, 5 to 4, 5 at 2 minutes after the start of mixing 2. The value of pH at $23^{\circ}C$ was higher than the value of pH at $37^{\circ}C$ in all cements. 3. As the time elapsed, the pH in all cements rose. The 20 minutes after the start of mixing the range of acidity was from pH 5 to pH 6 except Poly F. 4. In polycarboxylate cement, the different value of acidity at $23^{\circ}C$ and $37^{\circ}C$ was greatest. 5. The curve pattern of acidity in Unident was similar to that in Poly F cement The pH value of Unident was higher then that of Poly F, and value of pH in the curve pattern of acidity in Confit were similar to those in Super cement.

• Journal of the Korean Society of Safety
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• v.30 no.2
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• pp.56-62
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• 2015

The purpose of this study was to identify the relationship between the index of Electrocardiography(LF/HF) and the occurrence of drowsiness driving while driving in a simulated situation. Participants were 31 undergraduate students with an experience in driving and they participated 30 minutes driving under enough sleep condition and 1 hour under the sleep deprivation condition. The Euro Truck Simulator II was used for driving simulation task and ECG and perceived drowsiness of each participants were measured during two driving conditions. Perceived sleepiness recorded by the checklist every 10 minutes and ECG data extracted before and after 15 seconds of every 10 minutes to verify the relationship between two variables. The results showed that the level of perceived sleepiness under sleep deprivation condition was higher than that under the enough sleep condition, and the level of LF/HF under sleep deprivation condition was lower than that under the enough sleep condition. In addition, the result of analysis of repeated measure ANOVA for ECG indicated that authentic sleepiness revealed in 20 minutes after the start of driving under the sleep deprivation condition. However, the result of perceived drowsiness indicated that authentic sleepiness revealed in 30 minutes after the start of driving. These result suggest that the time difference between biological and perceived response on drowsiness may be exist. Finally, the significant negative correlation between the LF/HF level and perceived drowsiness was observed. These findings suggest that ECG(LF/HF) can be an possible index to measure drowsiness driving.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.6
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• pp.38-44
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• 2010

The shock wave and boundary layer interaction patterns in an over-expanded rocket nozzle are associated with the production of undesirable side-forces during the start-up and shut-down processes of the engine. In the present work, a computational study is carried out to investigate the effect of the transient nozzle pressure ratio (NPR) on the flow fields inside the nozzle. The unsteady, compressible, axisymmetric, Navier-Stocks equations with SST k-${\omega}$ turbulence model are solved using a fully implicit finite volume scheme. NPR is varied from 2.0 to 10.0, in order to simulate the start-up and shut-down processes of the rocket engine. It is observed that the interaction patterns and the hysteresis phenomenon strongly depend on the time variation of NPR, leading to significantly different characteristics in the lateral forces.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.191-199
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• 2008

The purpose of this study was to analyze movement of inline skate players at inline roller skate T300m start so that we can find effective starting movement, and provide basic and scientific materials in improving performance of inline roller skaters for T300m inline roller skating. In doing so, five Korean national representative inline skaters who elected in 2008 Korean National Inline Roller Skating Cup were taped during the cup and analyzed through 3D viewing in terms of their starting movement Conclusions of the analysis were as follows: First, the better the record of starting phase is the shorter average of contact time on track. Second, to improve starting speed, players raised their body just like running instead of lowering them when gliding. players could shorten their strike and moved faster in order to accelerate, and it was more effective to speed up when they quickly switched from running to gliding. Third, the five country-representative players speeded up by bending their knees to a greater degree in order to improve stability. And then the most effective way was believed to minimize track connection of skating at starting in each phase.

• Journal of Digital Convergence
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• v.16 no.6
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• pp.335-341
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• 2018

This study is to innovate policy service development by utilizing beneficiary - centered service design to public information and public data and services that citizens can experience. The Gov 3.0 Design Group operated by the Dongbuk Regional Bureau of Statistics in Daegu in 2015, proposed a 'start-up decision support service' for pre-founders, using data mining on the GIS spatial information held by the Statistical Office and real-time settlement information of credit card companies. For this, service design process and methodology were adopted and participation of various stakeholders. This study suggests that national design activity based on service design is effective in transforming public service based on government information disclosure. It is also worthwhile as an approach that can be considered when the government wants to release or open information or public data in useful form to the public.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.180-184
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• 2013

In this paper, a low power antenna switch controller IC is designed using a silicon-on-insulator (SOI) CMOS technology. To improve power handling capability and harmonic distortion performance of the antenna switch, the proposed antenna switch controller provides 3-state logic level such as +VDD, GND, and -VDD for the gate and body of switch of FETs according to decoder signal. By employing input-coupled current ring oscillator and hardware efficient level shifter, the proposed controller greatly reduces power consumption and hardware complexity. It consumes 135 ${\mu}A$ at a 2.5 V supply voltage in active mode, and occupies $1.3mm{\times}0.5mm$ in area. In addition, it shows fast start-up time of 10 ${\mu}s$.

• The Korean Journal of Emergency Medical Services
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• v.10 no.2
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• pp.53-62
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• 2006

Purpose: There has been an increase in the number of prehospital cardiac arrests due to the increasing number of cardiovascular diseases and the increase in the average age of the population. We performed this study to identify the proper resuscitation technique and AED to be used to increase the survival rate in prehospital cardiac arrests. Methods: This studied 159 victims with prehospital cardiac arrests(VF or VT rhythm) by EMT's Reports from January to August, 2005. Results: 108 of 159 victims(67.9%) were shocked by AED. Eighty of 159 victims(50.9%) were recorded with AED shock in prehospital cardiac arrests. A number of shocks is averaged 2.19; 46.2% of one-shock and 86.1% of 1-3 shock. EMS first-tier response interval from time of dispatch to scene arrival was 5.88 minutes, from scene arrival to scene start was 7.36 minutes, from scene start to hospital admission was 9.91 minutes and from scene arrival to AED shock was 6.84 minutes. EMT provided advanced care to prehospital cardiac arrests: 97.5% in CPR, 10.1% in advanced airway management, 67.9% in AED shock. Conclusion: With the increase in cardiovascular disease and old age, the number of prehospital cardiac arrests has risen gradually. However, there were lack of CPR by bystander, defibrillation and advanced cardiac life support(ACLS) in prehospital stage. To improve the adequacy of basic life support and to increase the performance of ACLS, especially AED, we must create challenges to develop new protocols in prehospital care.

• The KIPS Transactions:PartB
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• v.13B no.6 s.109
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• pp.585-590
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• 2006

Although motion estimation Plays an important role in digital video compression, complex search procedure is required to find an optimal motion vector. To reduce the search time, the search start point should be set up properly md efficient search pattern is needed. If the overall motion of the torrent block can be predicted, motion estimation can be performed efficiently. In this paper. block types are classified using candidate vectors and the motion activity of the block is predicted which leads to the search start point close to the optimal motion vector. The proposed method proves to be about 1.5$\sim$7 times faster than existing methods with about 0.02$\sim$0.2(dB) improvement of picture quality in images with large movements.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.2
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• pp.268-275
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• 2011

This paper proposes two optimal path planning methods of a mobile robot using uDEAS (univariate Dynamic Encoding Algorithm for Searches). Before start of autonomous traveling, a self-controlled mobile robot must generate an optimal global path as soon as possible. To this end, numerical optimization method is applied to real time path generation of a mobile robot with an obstacle avoidance scheme and the basic path generation method based on the concept of knot and node points between start and goal points. The first improvement in the present work is to generate diagonal paths using three node points in the basic path. The second innovation is to make a smooth path plotted with the blending polynomial using uDEAS. Effectiveness of the proposed schemes are validated for several environments through simulation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.132-141
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• 2006

Artificial structures have been designed as pilot structures to promote the creation and restoration of tidal flats. However, little information is available as to whether such artificial construction affects the macrobenthic community structure. We monitored the variation of the macrobenthic community structure and species composition near natural and artificial structures (seaweed and a timber fence) on the tidal flats near the Iwon Dike, Korea. In total, 137 macrobenthic species were recorded during this study, predominantly crustaceans (47%), polychaetes (18%), and molluscs (27%). Polychaetes comprised over 50% of the total density, followed by gastropods (38%) and crustaceans (11%). Macrobenthic species composition in the artificial and natural areas, was initially similar, but it differed after 7 months. The gastropod Umbonium thomasi, the most dominant species, was present at both sites in the first month after the start of the experiment, but disappeared at the artificial sites within 7 months, suggesting disturbance by the environmental factors. The number of species and diversity (H') varied significantly within sites at the beginning of the experiment, but no difference was observed after 7 months. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure between the artificial and the natural areas from 7 months after the start of the experiment, except from 18 to 21 months. The community structures were mainly influenced by U. thomasi. Community structure at the artificial sites was affected by environmental variables, such as carbon, COD/IL sulfide, loss of ignition, kurtosis and silt, which changed over time. We observed no significant correlations between environmental variables and the dominant species, except in the case of Spio sp. and Macrophthalmus dilatatus, suggesting that the biological interactions and temporary disturbances such as typhoon, as well as the effects of artificial structures may also be important regulating factors in this system.