• Corrosion Science and Technology
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• v.19 no.4
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• pp.196-202
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• 2020

The air vent connected to a heat supply pipeline in the district heating system has been used to eliminate the existing air in the pipe, which has a detrimental effect on corrosion durability and heat efficiency. Recently, the air vent installed under a manhole for 22 years was corroded and several pinholes were detected in the front-end of the air vent. To identify the cause of the failure, thickness reduction, corrosion products, and water quality were examined. The corrosion damage was significant at the outside of the front-end of the air vent where the insulator was covered. While a thin oxide layer was formed in the interior of the tube, the coarse and porous corrosion products consisting of magnetite and hematite were found externally. Water flowing into the thermal insulator was absorbed by the insulator following hydrolysis. The hydrolyzed insulator ejected the corrosion factors such as Cl^-, SO₄^2-, and NH₄⁺. The findings suggest that the corrosion under insulation due to rain water is the main cause of the underlying failure in the air vent.

• The Korean Journal of Rehabilitation Nursing
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• v.5 no.2
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• pp.217-225
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• 2002

Purpose : This research is aimed at developing a substantive theory related to the experience of adjustmented hemodialysis patients by identifying and analyzing the nature, process, and types of adjustment experienced by them. For this purpose, this study takes a grounded theory approach. Method : Data were collected from April, 2002 through September, 2002 through in-depth interviews and close observations of eleven hemodialysis patients who have experienced adjustment. With their consent, the interviews were recorded by audio tapes and later transcribed. Observation memos were also prepared on the subjects' behavior during the interviews. Data collection continued until saturated. The data were analyzed into concepts, subcategories, and categories with the open coding process. The axial coding was done to identify the relationships of the concepts and categories. And the selective coding was done to develop a core category, which is the central phenomenon of the hemodialysis patients who experienced adjustment. Result : This process resulted in 88 concepts, which may be grouped into 24 subcategories and 6 core categories. The 6 categories, in fact, depict the process of changes the patients experience from the sense of crisis, self-control, new life meaning, support system, coping ability, and quality of life improvement. And its core is self-control, which encompasses the dynamic stages from recognition, change attempts, belief solidification, and empowerment. Conclusion : The results of the research offer the following implications. First, research on adjustment is a formative stage in nursing, it is imperative for nursing researchers to develop them, which may be more relevant to nursing. Second, it is important to develop nursing intervention techniques that may be most effective in adjustment of hemodialysis patients and at the same time for each stage of changes taking place in adjustmented hemodialysis patients.

• Phonetics and Speech Sciences
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• v.3 no.1
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• pp.103-110
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• 2011

Idiopathic Parkinson's Disease patients' speech is hypokinetic dysarthria and their speech is possibly the consequence of impaired respiratory support. The purpose of this study was focused on the respiratory characteristics of speech breathing in de novo IPD who were not given prior vocal or anti-Parkinson treatment. A total of 40 subjects participated in the study: 20 de novo IPD patients between the ages of 50 and 80, and 20 normal subjects with similar age, height, and weight matches. Forced Expiratory Vital Capacity (FVC), Forced Expiratory Volume in 1 sec (FEV1) and $FEV_1$ as a percentage of FVC (FEV1/FVC) was measured with a PC-based spirometer (Cosmed). In addition, Maximum Phonation Time (MPT), Mean Airflow Rate (MFR), Subglottal Pressure (Psub) and the number of syllables produced per breath were measured with a Phonatory Aerodynamic System (Kay PENTAX). All subjects were asked to read a standardized Korean paragraph and the following measurements were obtained from the task. Results indicated no statistically significant differences in respiratory function (FEV1/FVC%) and aerodynamic function between the two groups, but the number of syllables per breath was significantly lower in the IPD patient group than in the normal group and it could be predicted by FVC and MFR. Therefore, the study shows that the MFR from the lungs during speech in de novo IPD patients is used inefficiently.

• Journal of Korean Association for Spatial Structures
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• v.13 no.2
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• pp.83-91
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• 2013

The core aim of this dissertation is to empirically scrutinize a strength characteristic of beam-column frame subjected to the cyclic lateral load, a beam-column frame of un-reinforced masonry wall, and a shear wall frame. First and foremost, I embark upon making three prototypes vis-$\grave{a}$-vis this research. By conducting this process, I touch on an analysis of cyclic behavior and a damage characteristic of the beam-column frame, the beam-column frame of un-reinforced masonry wall, and the shear wall frame. What is more, through the previous procedure, the next part delves into the exact stress transfer path and the destructive mechanism to examine how much and how strong the beam-column frame of un-reinforced Masonry Wall does have a resistance capacity against earthquake in all the architecture constructed by the above-mentioned frame, as well as school buildings. In addition to the three prototypes, two more experimental models, a beam-column frame and shear wall frame, are used to compare with the beam-column frame of un-reinforced masonry wall. Lastly, the dissertation will suggest some solutions to improve the resistance capacity against earthquake regarding all constructions built with non bearing wall following having examining precisely all the analysis with regard to not only behavior properties and the damage mechanism of the beam-column frame and the beam-column frame of un-reinforced Masonry Wall but also the resistance capacity against earthquake of non bearing wall and school buildings.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.3
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• pp.379-386
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• 2003

Statement of problem. Resin cements are widely used in adhesive dentistry specially on all ceramic restorations. It is needed to find out adequate bonding strength between different porcelain surface treatments, commercially available porcelains, and different resin cement systems. Purpose. The purpose of this study was to evaluate shear bond strength of resin cements bonded to porcelains in three different modalities; 5 different porcelain surface treatments, 3 different resin cement systems and 3 different commercially available pressable porcelains. Material and Method. This study consisted of 3 parts. Part I examined the effect of five different surface treatments on the pressable porcelain. Fifty discs (5 mm in diameter and 3 mm in height) of Authentic porcelain were randomly divided into 5 groups (n = 10). The specimens were sanded with 320 grit SiC paper followed by 600 grit SiC paper. The specimens were treated as follow: Group 1-Sandblasting (aluminum oxide) only, Group 2 - sandblasting/ silane, Group 3 - sandblasting/ acid etching/ silane, Group 4 - acid etching only, Group 5 - acid etching/ silane. Part II examined the shear bond strength of 3 different resin cement systems (Duolink, Variolink II, Rely X ARC) on acid etching/ silane treated Authentic pressable porcelain. Part 3 examined the shear bond strength of Duolink resin cement on 3 different pressable porcelains (Authentic, Empress I, Finesse). All cemented specimens were stored in distilled water for 2 hours and tested with Ultradent shear bond strength test jig under Universal Instron machine until fracture. An analysis of variance(ANOVA) test was used to evaluate differences in shear bond strength. Result. The shear bond strength test resulted in the following: (1) Acid etched porcelains recorded greater shear bond strength values to the sandblasted porcelains. (2) Silane treated porcelains recorded greater shear bond strength values to non-silane treated porcelains. (3) There was no significant difference between sandblasting/ acid etching/ silane treated and acid etching/ silane treated porcelains. However those values were much higher than other three groups. (4) The shear bond strength with Variolink II was lower than the value of Duolink or Rely X ARC. (5) The shear bond strength of Finesse was lower than the value of Authentic or Empress I.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.1-5
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• 2009

STATEMENT OF PROBLEM. Poor wettability of denture relining materials may lead to retention problems and patient discomfort. PURPOSE. Purpose of this study is to compare and evaluate wettability of nine denture relining materials using contact angle measurements under air and water storage over time. MATERIAL AND METHODS. Nine denture relining materials were investigated in this study. Two heat-curing polymethyl-methacrylate(PMMA) denture base materials: Vertex RS, Lang, one self-curing polyethyl-methacrylate(PEMA) chairside reline resin: Rebase II, six silicone relining materials: Mucopren soft, Mucosoft, $Mollosil^{{R}}$ plus, Sofreliner Touch, GC $Reline^{TM}$ Ultrasoft, Silagum automix comfort were used in this experiment. Contact angles were measured using high-resolution drop shape analysis system(DSA 10-MK2, KRUESS, Germany) under three conditions(in air after setting, 1 hour water storage, and 24 hours water storage). Nine materials were classified into three groups according to material composition(Group 1: PMMA, Group 2: PEMA, Group 3: Silicone). Mean values of contact angles were compared using independent samples t-test and one-way ANOVA, followed by a Scheffe's post hoc analysis($\alpha$=0.01). RESULTS. Contact angles of materials tested after air and water storage increased in the following order: Group 1(PMMA), Group 2(PEMA), Group 3(Silicone). Heat-cured acrylic denture base resins had more wettability than silicone relining materials. Lang had the highest wettability after 24 hours of water storage. Silicone relining materials had lower wettability due to their hydrophobicity. Wettability of all denture relining materials, except Rebase II and $Mollosil^{{R}}$ plus, increased after 24 hours of water storage. CONCLUSIONS. Conventional heat-cured resin showed the highest wettability, therefore, it can be suggested that heat-cured acrylic resin is material of choice for denture relining materials.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.37-40
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• 2009

STATEMENT OF PROBLEM. Implant drivers are getting popular in clinical dentistry. Unlike to implant systems with external hex connection, implant drivers directly engage the implant/abutment interface. The deformation of the implant/abutment interface can be introduced while placing an implant with its implant driver in clinical situations. PURPOSE. This study evaluated the change of rotational freedom between an implant and its abutment after application of different insertion torques. MATERIAL AND METHODS. Three kinds of internal connection implants were utilized for the current study($4.5{\times}12\;mm$ Xive, $4.3{\times}11.5\;mm$ Inplant Magicgrip, $4.3{\times}12\;mm$ Implantium MF). An EstheticBase, a 2-piece top, a Dual abutment was used for its corresponding implant system. The rotational freedom between an implant and its abutment were measured before and after applying 45, 100 Ncm insertion torque. Repeated measures ANOVA was used for statistical analysis. RESULTS. Under 45 Ncm insertion torque, the rotational freedom between an implant and its abutment was significantly increased in Xive(P = .003). However, no significant change was noted in Inplant Magicgrip and Implantium MF. Under 100 Ncm torque, both in Xive(P = .0005) and Implatium MF(P = .03) resulted in significantly increased rotational freedom between the implant and its abutment. DISCUSSION. The design of the implant/implant driver interface effectively prevented the deformation of implant/abutment interface. Little change was noted in the rotational freedom between an implant and its abutment, even though the insertion torque was far beyond clinical application. CONCLUSIONS. The implant/abutment joint of internally connecting implants were quite stable under insertion torque in clinical situation.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.342-350
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• 2020

Acoustic and vibration research activities for the structural development of Korean space launch vehicles are introduced in this paper. Various dynamic loads exerted on a launch vehicle during its operation are summarized. The acoustical design method of payload fairings which protect satellites from harsh launch environment was reviewed. Several acoustic research activities were performed to enhance the analytical prediction ability during the development period of the Naro and the Nuri launcher. Specifically, the following research activities are reviewed: a test and vibro-acoustic analysis of composite cylinders whose layup properties are varied, a research on low-frequency acoustic load reduction by an acoustic resonator array and an acoustic test on the cylinder part of the Naro payload fairing. A vibro-acoustic analysis result for the Nuri launcher was introduced and predicted acoustic and vibration levels and measured ones are shown to be in a good agreement.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1733-1736
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• 2006

A new biologically active peptide with structural similarity to neuromedin N (NMN) has been isolated from extracts of visceral tissue of the African lungfish, Protopterus dolloi, using the rectum of the quail as the bioassay system. The primary structure of NMN-related peptide was established as Lys-Ala-Pro-Tyr-Ile-Leu-OH ([$Ala_2$]-NMN) and contained one substitution ($Ala_2\rightarrow$Ile) compared with the porcine NMN. [$Ala_2$]-NMN was found to have an excitatory effect on rectal muscle tissues of quail (Coturnix japonica), newt (Cynops pyrrhogaster) and black bass (Micropterus sulmoides). The threshold concentration of [Ala2]-NMN for contraction of C. japonica muscle was found to be approximately $10^-11$M. [$Ala_2$]-NMN showed contractile activities in the following order: C. japonica > C. pyrrhogaster > M. sulmoides. The identification of [Ala2]-NMN provides evidence that NMN family, hitherto confined to mammals, has a widespread occurrence in lungfish.

• Journal of Korea Port Economic Association
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• v.29 no.3
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• pp.95-111
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• 2013

The purpose of this study is to draw out the trade effect of the Korea ASEAN FTA by carrying out a panel analysis. For achieving such a purpose, Panel Unit Root, Panel Cointegration Test, Pooled OLS, Hausman Test, Fixed Effect, Random effect are performed. The last 15 years's data over the period of 1997 to 2011 concentrated on the ASEAN countries such as Indonesia, Malaysia, Philippine, Singapore, Thai, Vietnam is used in this study. Major implications are summarized as following. First, our government need to maximize the effect derived from conclusion of FTA(Free Trade Agreement) in order to enhance the competitive edge through obtaining a stable foreign market. Second, it necessary for our government to improve a national system by orienting a FTA conclusion complying with WTO's product and service-related regulation.