• Journal of the Korea Furniture Society
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• v.28 no.2
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• pp.111-117
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• 2017

Recently, as people's interest in wood has increased, the use of wood as household and landscape decking materials has increased. As the deck material, imported wood such as synthetic wood, Ipe, and Malas was used in addition to the existing preserved wood, but recently deck use has been activated as part of the activation of domestic materials. As an important quality factor in the selection of such decking materials, various durability along with weatherability for long - term use is required for maintenance. Generally used tropical hardwoods have excellent weatherability and durability without additional preservative treatment. However, the domestic larch is a wood species with a higher specific gravity and durability than ordinary conifers. However, it has not yet been used as a deck material due to lack of comparative studies on its characteristics. Therefore, hardness and durability of wood were measured using six specimens of Ipe, Massaranduba, Malas, Douglas-fir, Larch and Torrefied-Larch. Density Profile was used to measure the density, and Brinell hardness test and resistance test against momentary impact were carried out for the test of resistance to static load. Also, The hardness and durability of wood were measured by castor test with resistance test against dynamic load, as well as, nail down test by experiment on surface hardness and durability. As a result of the experiment, the hardness was increased in proportion to the density, and it was confirmed that the imported lumber was harder and durable than the domestic larch.

• Resources Recycling
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• v.4 no.3
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• pp.26-31
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• 1995

The leaching characteristics of manganese nodules were investigated in dilute hydrochloric acid solution using copper malie as a reductant. Thc capper matte has been found to be an effective reductant for exhacting morc than 96% of Mn, 95% of Ni, 91% of Ca, 88% of Cu and 36% of Fe when leached in 2.5 M HCI at 70$^{\circ}$C for 2hr. The dissolutions of Mu, Co, and Ni depend on thc amaunt of added cappcr matte. 7he ratin of liquid and solid is an important [actor on the extraction of metals during leaching The dissolution af Mn, Co, Ni and Cu incrcascd w~th the increase in temperalure of leachant. The leaching rates of Mn, Co, NI and Cu from manganese nodule m the presznce of copper matte is limited by bath thc surface chemical reaction and pare diffusion processes. Thc activation energies far Mn. Co: Ni and Cu were 17. 61, 12.8, 17.2 and 57.88 KcaUmol, rcspcctively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6403-6410
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• 2015

Medical polymer PLGA is biocompatible, biodegradation, mechanical characteristic and biostability, and the degradation time can be adjust by controlling the number of monomer. In this paper, PLGA membranes have different composition ratio by L/D type was prepared by phase transition method. And the PLGA membrane in phosphate buffered saline(PBS) at the different test temperatures for different periods of time to examined for change in mass and measured the pH of degradation media. Measurement of Tg and surface structure was performed using a DSC and Stereoscopic microscope. As the molecular weighter increase, hydrolysis rate was decrease in geometrical progression. According to the composition ratio by L/D type, degradation rate and the change of pH are large.

• Nuclear Engineering and Technology
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• v.39 no.3
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• pp.231-236
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• 2007

Due to the occasional occurrences of stress corrosion cracking(SCC) in steam generator tubing(Alloy 600), degraded tubes are removed from service by plugging or are repaired for re-use. Since electrodeposition inside a tube does not entail parent tube deformation, residual stress in the tube can be minimized. In this work, tube restoration via electrodeposition inside a steam generator tubing was performed after developing the following: an anode probe to be installed inside a tube, a degreasing condition to remove dirt and grease, an activation condition for surface oxide elimination, a tightly adhered strike layer forming condition between the electro forming layer and the Alloy 600 tube, and the condition for an electroforming layer. The reliability of the electrodeposited material, with a variation of material properties, was evaluated as a function of the electrodeposit position in the vertical direction of a tube using the developed anode. It has been noted that the variation of the material properties along the electrodeposit length was acceptable in a process margin. To improve the reliability of a material property, the causes of the variation occurrence were presumed, and an attempt to minimize the variation has been made. A Ni alloy electrodeposition process is suggested as a primary water stress corrosion cracking(PWSCC) mitigation method for various components, including steam generator tubes. The Ni alloy electrodeposit formed inside a tube by using the installed assembly shows proper material properties as well as an excellent SCC resistance.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.2
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• pp.89-94
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• 2015

PURPOSE: The aim of this study was to determine the effect of device considering Mckenzie type for the subjects with forward head posture (FHP). METHODS: The subjects were 35 patients with FHP (mean age was $23.7{\pm}2.8$ years; mean height; $172.1{\pm}11.7$, mean weight; $65.8{\pm}13.9$, mean NDI(Neck Disability Index; $3.7{\pm}3.2$, mean FHP; $6.7{\pm}2.2$). We measured the posture with the Body style S-8.0(LU Commerce, South Korea) to evaluate the FHP. We collected the surface EMG(Myosystem 1400, Noraxon, USA) data to quantify changes in normalized activation levels of muscles in SternoCleidoMastoid muscle(SCM), Scalenus Anterior(SA), Trapezius upper fiber(TU) and Splenius Cervicis(SC), during the subjects were instructed to glide their head into a "chin-in" position for a retraction without and with device. RESULTS: The condition with device significantly decreased the %RVC of SA($90.84{\pm}40.54$), SCM($74.98{\pm}43.65$) and TU($67.60{\pm}47.83$) compared to the condition without device(SA;$100.39{\pm}56.32$, SCM;$119.03{\pm}109.26$, Trapezius;$80.55{\pm}39.27$). But the %RVC of capitis($65.87{\pm}47.83$) with device was increased($70.82{\pm}52.78$). There was significant difference in the %RVC between SCM and Trapezius muscle in two conditions. CONCLUSION: New device for FHP reduces the EMG activities of the TU, SCM and SA muscle. We have to develop the function of feedback to facilitate the motion in the future.

• Journal of The Korean Society of Integrative Medicine
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• v.2 no.1
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• pp.15-21
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• 2014

Purpose : The aim of this study was to find out differences between muscle activity of quadriceps according to hip angle. Method : 40 healthy adults produced maximum isometric muscle contraction of quadriceps femoris and each part of the quadriceps femoris were measured with a surface EMG in hip joint angle of $90^{\circ}$, $135^{\circ}$, $180^{\circ}$. Result : There was no significant difference between muscle activity of vastus medialis and lateralis according to hip angle. But there was significant difference in muscle activity of rectus femoris and the muscle activity was maximum at 135 degrees of hip angle. Conclusion : In conclusion, maximum muscle activation of rectus femoris is affected by hip angle, and the findings from this study may be helpful for physical therapists in selecting hip position when instructing patients to do Q-setting exercise. So, we suggest that patients perform Q-setting exercise at 135 degrees of hip angle for the best result.

• Bulletin of the Korean Chemical Society
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• v.2 no.4
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• pp.142-147
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• 1981

A blend polymeric system composed of poly(methyl methacrylate) (PMMA or PM) and polystyrene (PS) dissolved in chloroform was rheologically studied. The viscosities ${\eta}_{bl}$ of the blend system with various blending ratios ${\chi}$ changing from zero (pure PS solution) to unity (pure PMMA solution) were measured at $25{\circ}C$ as a function of shear rates ${\dot{s}}$ by using a Couette type viscometer. ${\eta}_{bl}$ at a given ${\dot{s}}$ decreased exponentially with ${\chi}$ reaching asymptotic constant value of ${\eta}_{bl}$ ; ${\eta}_{bl}$ at a given ${\chi}$ is greater at a smaller ${\dot{s}}$. These results are explained by using Ree-Erying's theory of viscosity, ${\eta}_{bl}=(x_1{\beta}_1/{\alpha}_1)_{b}_1＋ (x_2{\beta}_2/{\alpha}_2)_{bl}[sinh^{-1}{\beta}_2(bl) {\dot{s}}]/{\beta}_2(bl){\dot{s}}$. The Gibbs activation energy ${\Delta}G_i^\neq$(i = 2 for non-Newtonian units) entering into the intrinsic relaxation time ${\beta}$ is represented by a linear combination ${\Delta}G_i^\neq(bl) ={\chi}{\Delta}G_i^{\neq}_{iPM}+(1-{\chi}){\Delta}G_i^{\neq}_{iPS}$;the intrinsic shear modulus$[[\alpha}_i]^{-1}$ is also represented by $[{\alpha}_i(bl)]^{-1}={\chi}[{\alpha}_{iPM}]^{-1}+(1-{\chi})[{\alpha}_{iPS}]^{-1}$ and the fraction of area on a shear surface occupied by the ith flow units $x_i(bl)$ is similarly represented, i.e., $x_i(bl) = {\chi}x_{iPM}+(1-{\chi})x_{iPS}$. By using these ideas the Ree-Eyring equation was rewritten which explained the experimental results satisfactorily.

• Bulletin of the Korean Chemical Society
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• v.7 no.5
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• pp.395-399
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• 1986

Intramolecular proton transfer equilibria of acetamide and methyl carbamate have been studied theoretically by MNDO MO method. For both substrates, carbonyl-O protonated tautomer was found to be the most stable form, the next most stable one being N-protonated form. Gas phase proton transfers take place by the 1,3-proton rearrangement process and in all cases have prohibitively high activation barriers. When however one solvate water molecule participates in the process, the barriers are lowered substantially and the process proceeds in an intermolecular manner through the intermediacy of the water molecule via a triple-well type potential energy surface; three wells correspond to reactant(RC), intermediate(IC) and product complex(PC) of proton donor-acceptor pairs whereas two transition states(TS) have proton-bridge structure. General scheme of the process can be represented for a substrate with two basic centers(heteroatoms) of A and B as, $$ABH\limits^+\;+\;H_2O\;{\to}\;ABH\limits^+{\cdots}{\limits_{RC}}OH_2\;{\to}\;AB{\cdots}H\limits_{TS}^+{\cdots}{\limits_{1}}OH_2\;{\to}\;AB{\cdots}{\limits_{IC}}H\limits^+OH_2\;{\to}\;BA{\cdots}H\limits_{TS}^+{\cdots}{\limits_{2}}OH_2\;{\to}\;BA H\limits^+{\cdots}{\limits_{PC}}OH_2\;{\to}\;BAH\limits^+\;+\;H_2O$$ Involvement of a second solvate water had negligible effect on the relative stabilities of the tautomers but lowered barrier heights by 5∼6 Kcal/mol. It was calculated that the abundance of the methoxy-O protonated tautomer of the methyl carbamate will be negligible, since the tautomer is unfavorable thermodynamically as well as kinetically. Fully optimized stationary points are reported.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.3
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• pp.127-133
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• 2019

PURPOSE: The aim of this study was to obtain detailed and quantified data concerning the effects of plantarflexor fatigue induced to the non-paretic side on muscle activities of the bilateral lower extremities during walking in chronic stroke patients. METHODS: In this study, chronic stroke patients were evaluated for six months after the onset of stroke. To induce the non-paretic plantarflexor fatigue, 20 chronic stroke patients were asked to perform their given fatigue affecting assignments, which were presented in a forced contraction fatigue test method, until the range of motion of the plantarflexor was reduced to less than 50%. The muscle activities of the rectus femoris, tibialis anterior and gastrocnemius in the paretic and non-paretic lower extremities were measured using a wireless surface EMG before and after muscle fatigue induction. RESULTS: The findings showed that after plantarflexor fatigue was induced on the non-paretic side, a significant decrease in muscle activities of the rectus femoris on the paretic side was noted (p<.05). The muscle activities of the tibialis anterior and gastrocnemius were also observed to decrease, but, these results were not statistically significant (p>.05). In the non-paretic side, there was a significantly decrease in the muscle activities of the rectus femoris, tibialis anterior, and gastrocnemius (p<.05). CONCLUSION: These finding suggest that the muscle fatigue of the non-paretic plantarflexor affects not only the muscle activity of the ipsilateral lower extremity but also the muscles activity of the contralateral lower extremity. This highlights the necessity of performing exercise or training programs that do not cause muscle fatigue in clinical aspects.

• The Journal of Korean Physical Therapy
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• v.31 no.4
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• pp.199-203
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• 2019

Purpose: This study investigated the effects of shoulder protraction exercise according to weight by examining the surface electromyography (EMG) amplitude in the serratus anterior (SA), upper trapezius (UT), and pectoralis major (PM) as well as the activity ratio of each muscle. Methods: Twenty three winging scapula subjects participated in the study. The subjects performed scapula protraction at shoulder $90^{\circ}$ flexion and $60^{\circ}$ horizontal abduction with up to four (none, 1kg, 1.5kg, and 2kg) dumbbells in the supine position. The EMG data were collected from the dominant side muscles during a shoulder protraction exercise according to weight in the supine position. One way repeated measures analysis of variance (ANOVA) was used to compare the normalized activities of the SA, UT, and PM and the ratios of PM/SA and UT/SA. Results: The results showed that the activities of both the SA and UT were highest for the shoulder protraction exercise at 2kg in the supine position. The UT/SA ratio also was the lowest for exercise at 2kg. On the other hand, the activities of both the UT and PM/SA ratio were similar under all conditions. Conclusion: These results show that there is a need to selectively strengthen the SA muscle in the case of patients with the shoulder dysfunction. In particular, it is necessary to weigh 2kg when performing shoulder protraction exercises in the supine position to activate the SA muscle in patients with a winging scapula.