• Membrane Journal
• /
• v.13 no.2
• /
• pp.110-117
• /
• 2003

Sulfonated polyimides had been utilized and studied widely as available materials in chloro-alkali electrolysis, cationic exchange resins, and so on. However, a slow decrease in performance during experiments had been reported, which could be attributed to a loss of ionic conductivity related to either a continuous dehydration or polymer degradation. One of main reasons to account for the degradation of sulfonated polymers is the hydrolysis leading to polymer chain scission and decrement of molecular weight. Therefore, the objective of our study was to investigate possible imide cycle and additional ester bond cleavage connected with $SO_3$H presence under hydrated condition. In order to confirm and obtain as clear information as possible about breakages of bonds via $^1H\; and \;^{13}C$ NMR and IR spectroscopic analyses, our study was performed by model compound. Consequently, model compounds with both phthalic and naphthalenic imide ring and ester bonds were synthesized to evaluate the hydrolysis stability of sulfonated polyimide. The experiments were performed for prepared model compounds before and after aging in deionized water at $80^{\circ}C$ and were terminated by lyophilization technique. The aging products were finally analyzed by NMR and IR spectroscopy.

• Conservation Science in Museum
• /
• v.15
• /
• pp.122-137
• /
• 2014

The National Museum of Korea own a historical document box ^K976 that was once used to store Joseon Wangjo Sillok ^{Annals of the Joseon Dynasty} of the Joseon Dynasty. The rectangular box has a lid, and the entire surface is varnished with black lacquer. The wood of the box had become warped and the upper part of the wooden frame had been damaged. In some areas, the paint was flaking off, exposing the underlying wood, and an iron ring that connected the lid to the body of the box was missing. Thus, in 2013, Conservation Science Department in National Museum of Korea began to repair and restore the Joseon document box. Before the treatment, analyses were conducted to examine the box's structure, damaged parts, species of wood, and lacquering techniques. The wood was found to be that of a linden tree. As for the lacquering technique, the surface of the box was first coated with a layer of lacquer and bone ash, and then covered with Korean traditional paper. Next, the box was painted with a layer of mud and ashes, followed by a layer of black pigment mixed with soot, and then varnished again with lacquer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.9 s.112
• /
• pp.900-912
• /
• 2006

A GPS receiving antenna installed in the missile's warhead is designed and fabricated at a center frequency 1.575 GHz. The circular shaped antenna is installed in the middle of the warhead where the antenna's patch and the ground plane are connected with a hollow cylindrical shaped short pin. Using the dual feeding and phase difference method, an omni-directional radiation pattern which direction is normal to the missile's axis(H-plane) is obtained. The optimized diameters of the circular patch and the cylindrical ring typed shorting pin of the GPS receiving antenna which use the FR4.material(dielectric constant $\varepsilon_r=4.6$) are 59.5 mm and 14 mm, respectively. The cylindrical body with diameter 100 mm and height 500 mm is attached to the lower part of the warhead in order to complete the missile figure. The radiation patterns are measured by changing the angle and phase between the dual feeding points. When the phase difference of dual feeding is $100^{\circ}$ and the angle between the dual feeding points is $100^{\circ}$, the nearly omni-directional radiation pattern in the H-plane is obtained. In this case, the antenna gain is -5.55 dBd and the relative level difference between the maximum and the minimum radiation intensity is 3.98 dB.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.4
• /
• pp.27-34
• /
• 2016

In the train system, railway vehicles are connected in a line. Therefore, this feature should be considered in composing network topology in a train system. Besides, inter-car communication should be distinguished from in-car communication. As for the inter-car communication, the hybrid topology was proposed to use rather than the conventional ring, star, daisy-chain, and bus topologies. In the hybrid topology, a number of cars are bound to be a group. Then star topology is used for the communication in a group and daisy-chain topology is used for the communication between groups. Hybrid topology takes the virtue of both star and daisy-chain topologies. Hence it maintains communication speed with reducing the number of connecting cables between cars. Therefore, it is important to choose the number of cars in a group to obtain higher performance. In this paper, we focus on the optimization of hybrid topology for railway cars. We first assume that the size of data and the frequency of data production for each car is identical. We also assume that the importance for the maximum number of cables to connect cars is variable as well as the importance of the communication speed. Separated weights are granted to both importance and we derive the optimum number of cars in a group for various number of cars and weights.

• Journal of the Korean Chemical Society
• /
• v.38 no.5
• /
• pp.359-365
• /
• 1994

The crystal stucture of hexapotassium undecahydrogen tetratungsto hexaantimonate(V) tetrahydrate has been determined from single crystal X-ray diffraction data. Crystal data are as follows: $K_6H_{12}[Sb_6W_4O_{36}]{\cdot}4H_2O$, Fw = 2360.62, tetragonal, I$4_1$/a, a = 10.799(1) ${\AA}$, c = 35.244(5) ${\AA}$, V = 4110.1(7) ${\AA}^3$, Z = 4, $D_x$ = 3.82 g$cm^{-3}$, $\mu(MoK\alpha)$ = 160.15 $cm^{-1}$, T = 293 K, final R = 0.0356 for 2400($F_0 > 3\sigma(F_0))$ independent reflections. The $[H_{12}Sb_6W_4O_{36}]^{-6}$ polyanion independently consists of one tungsten, two antimony, and nine oxygen atoms and belongs to the $\bar4(S_4)$ point group. This polyanion is formed by two open octahedra five membered ring of Sb(3)$O_6-W(1)O_6-Sb(2)O_6-W(1)O_6-Sb(3)O_6$ which is connected at right angle. The Sb-W, Sb-O, and W-O bond distances range from 3.2304(9) to 3.2403(5) $\AA$, 1.745(8) to 2.334(6) $\AA$, and 1.914(7) to 2.039(7) $\AA$, respectively.

• Analytical Science and Technology
• /
• v.18 no.4
• /
• pp.271-277
• /
• 2005

Urea in blood has been measured as an effective marker for diagnosis of renal function. Urea which is e end-product of nitrogen containing metabolites such as proteins is filtered through glomeruli of kidneys and then excreted as urine. If the renal function is deteriorated, the urea concentration in blood will be increased, from which the healthiness of renal function is judged. In order to improve the confidence of diagnosis results, the results must keep traceability chain to certified reference materials, which was certified by primary reference method. In this study, we proposed isotope dilution-liquid chromatography/mass spectrometry (ID-LC/MS) as a candidate primary method, in which $15^N_2$-urea is used as an internal reference material. The developed method is highly accurate in principle and is convenient as it does not require cumbersome derivatization. 0.1 mmol/L ammonium chloride was selected as a mobile phase for HPLC because it provided low interference in MS analysis of relatively low molecular weighted urea. HPLC and MS were connected with an electrospray ionization (ESI) interface of positive mode, which provided high sensitivity and reproducibility. The developed method was validated with internationally recognized reference materials, and we have obtained satisfactory results in an international ring trial. The expanded uncertainty calculated according to ISO guide was 1.8% at 95% confidence interval. The developed method is being used as a primary reference measurement method such as for certification of serum certified reference materials (CRMs).

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.2
• /
• pp.137-144
• /
• 2008

In this paper, a novel voltage-controlled oscillator(VCO) using the output matching network based on the harmonic control circuit is presented for improving the phase noise property. The phase noise suppression is achieved through the harmonic control circuit having the short impedances for both second-harmonic and third-harmonic components, which has been connected at the output matching network. Also, we have used the microstrip square open loop multiple split-ring resonator(OLMSRR) having the high-Q property to further reduce the phase noise of VCO. Because the output matching network based on the harmonic control circuit has been used for reducing the phase noise property instead of the High-Q resonator, we can obtain the broad tuning range by the low-Q resonator. The phase noise of the proposed VCO using the output matching network based on the harmonic control circuit and the microstrip square OLMSRR has been $-127.5{\sim}126.33$ dBc/Hz @ 100 kHz in the tuning range, $5.744{\sim}5.839$ GHz. Compared with the reference VCO using the output matching network without the harmonic control circuit and the microstrip line resonator, the phase noise property of the proposed VCO has been improved in 26.66 dB.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.5
• /
• pp.940-947
• /
• 2006

A variety of actuators fur an implantable artificial heart have been studied. They, all, however, share the disadvantages of a complicated energy conversion mechanism and of the need to use bearings. A ferrofluidic actuator directly drives magnetic fluids by applying a magnetic field to these fluids; it does not require bearings. In this study, the feasibility of a ferrofluidic actuator for an implantable artificial heart was studied. An way of two Poles of ring solenoids was mounted near the acrylic tube $({\phi}\;7.4mm)$. A rubber sack (volume : $2m{\ell}$ was connected to both ends of the acrylic tube. The sack were encased in a rigid chamber that had inlet and outlet ports. The acrylic tube and the rubber sack were filled with water encased in a rigid chamber magnetic fluid and the iron cylinder were immersed in the water. Two experiment method was conducted. 1) distance between stoppers were 72mm and 2) distance between stoppers were 104mm. A stroke volume was stability and $0.96m{\ell}$ was obtained in the experiment 1 and $1.92m{\ell}$ in the experiment 2. The energy efficiency of Experiment method 2 is about five times than Experiment method 2. A magnetic fluid-driven blood pump could be feasible if the magnetic fluid with high magnetization (3 times yester than the current value) is developed.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.8 no.5
• /
• pp.417-425
• /
• 2018

This paper proposes a safety management method that extracts ETA (event tree analysis) based scenario and combines ICT technology to reduce serious disasters occurring workplace for shipbuilding and offshore plant. The statistics of Safety and Health Agency and (previous)Ministry of Public Safety and Security show that the most frequent accident among the serious disasters related to shipbuilding and offshore plant is falling. The main cause of accidents is absence of a safety belt and safety belt ring. To solve these problems, we create ETA based scenarios to derive results based on safety considerations. Based on these results, we propose a solution by applying ICT technology for accident prevention. Deriving ETA based scenarios and ICT technology, the proposed solutions include a system for detecting the wearing of safety belts and safety helmets, a system for detecting whether or not the safety belts are connected, and a hook system for measuring safety distances. These safety related systems can reduce the probability of death of workers. By preventing accidents using the proposed method, we can reduce serious disasters in shipbuilding and offshore plant and establish systematic safety management.

• Journal of the Korean Wood Science and Technology
• /
• v.36 no.6
• /
• pp.77-87
• /
• 2008

Wooden model erosion control dam was made with pitch pine, of which the strength properties was evaluated. Wooden model erosion control dam was made with diameter 90 mm of pitch pine round posts treated with CUAZ-2 (Copper Azole), changing joint in three different types. In each type, erosion control dam was made in nine floor (cross-bar of five floors and vertical-bar of four floors), of which the hight was 790 mm. And then strength properties were investigated through horizontal loading test and impact strength test, and the deformation of structure through image processing (AICON 3D DPA-PRO system). In horizontal loading test of wooden model erosion control dam using round post of diameter 90 mm, whether there was stone or not did not affect strength much when using self drill screw, but strength was decreased by 23%. In monolithic type of erosion control dam using screw bar, strength was increased by 1.5 times and deformation was decreased when filling with stone. When reinforcing with screw bar that ring is connected to self drill screw, strength was increased by 4.8 times. In impact strength test of wooden model erosion control dam made with round post of diameter 90 mm, the erosion control dam connected with self drilling screw not filling with stone was totally destroyed by the 1st impact, and the erosion control dam using screw bar was ruptured at cross-bar at which 779 kgf of impact was loaded in the 1st impact. In the 2nd impact, the base parts were ruptured, and reaction force was decreased to 545 kgf. In the 3rd impact, whole base parts were destroyed, and reaction force was decreased to 263 kgf.