선창은 선박의 화물을 싣는 공간으로 구조적 문제로 인해 세정작업은 위험성이 크고 작업 난이도가 높은 작업이다. 이 연구에서는 전용 선창세정기의 설계 자료로 활용하기 위해 압력변화에 따른 분무특성을 고찰한 결과 노즐 형상의 최적화를 위한 변수 요소를 확인 하였다

In order to investigate the low-cycle fatigue behavior of Inconel 718 alloy used for pressure vessels, the strain-controlled fatigue test was performed in the room and high temperatures of 550°C. High temperature test was done using an electric furnace attached on the hydraulic fatigue test system. Tensile strength and elastic modulus of the Inconel 718 alloy at the temperature of 550°C decreased by 8% and 10%, respectively, compared to those at the room temperature. Subjected to the repeated cyclic loading under the strain-control, the material exhibited cyclic softening behavior with decreasing yield strength at both room and high temperatures. The low-cycle fatigue properties determined in this research could be effectively used for the fatigue life estimation of high temperature components made of Inconel 718 alloy.

Seismic analyses of a pile under a large rigid basement foundation embedded in the homogeneous soil layer were performed practically by a response displacement method assuming a sinusoidal wave form. However, it is hard to take into account the characteristics of a large mat foundation and a heterogeneous soil layer with the response displacement method. The response displacement method is relevant to the 2D problems for longitudinal structures such as tunnel, underground cave structure, etc., but might not be relevant with isolated foundations for building structures. In this study, seismic pile analysis by a pseudo 3D finite element method was carried out to compare numerical results with results of the response displacement method considering 3D characteristics of a foundation-soil system which is important for the building foundation analyses. Study results show that seismic analyses results of a response displacement method are similar to those of a pseudo 3D numerical method for stiff and dense soil layers, but they are too conservative for a soft soil layer inducing large soil pressures on the foundation wall and large pile displacements due to ignored foundation rigidity and resistance.

This study was undertaken to achieve a high bleaching efficacy with plasma, through longer application and reparative bleaching processes, by different shade evaluation methods. Extracted human teeth were divided into 6 groups (n=10). All teeth were treated in pairs. Low concentration of 15% carbamide peroxide (CP) was applied, with and without plasma, for 10, 20, and 30-min tooth bleaching, respectively. The bleaching procedure was repeated once daily for four days. The teeth were maintained in a moist environment provided by artificial saliva. The Vitapan Classical shade guide and Commission Internationale de L’Eclairage (CIELAB) color system were collectively used to measure the bleaching efficacy. Color evaluation was statistically analyzed using Student t-test and one-way analysis of variance (ANOVA) complemented by Tukey’s test. Combining the plasma with 15% CP showed significantly greater color changes compared to bleaching without plasma (p<0.05). A high bleaching efficacy with plasma is proportional to the repetitive application and the treatment time. A 30-min application with plasma provided the best bleaching. Repetitive bleaching showed lower probability of color relapse of the bleached tooth. The color change by shade guide correlated with the changes in CIELAB color system. A value of 1 color change units (CCU) conversion factor for overall color change (ΔE) values comparisons was 3.724 values. The two measuring methods provide a more accurate correspondence of color change. The repetitive and longer application for tooth bleaching, combined with plasma, has a strong bleaching effect and produces whiter teeth.

In general, polyethylene (PE), polyvinyl chloride (PVC), and ductile cast iron pipes are widely used in the water supply pipeline system. However, they have some disadvantages such as reduced durability due to material degradation, defects in connections, breakage of pipelines, and difficulties in continuous maintenance. To mitigate such problems, recently, research on durable and outstanding corrosion resistant glass fiber reinforced polymer plastic (GFRP) pipe is being actively conducted. GFRP is classified into the flexible pipe and when soil pressure and live load act on buried GFRP pipe, the load acting on the pipe is transferred to the surrounding soil. So, it should review the structural behavior and interaction between buried pipe and its surrounding soil because pipe will support the load with the surrounding soil together at the same time. To apply GFRP pipe for the water supply pipeline system, the structural reliability of GFRP water supply pipe buried underground should be investigated by examining the mechanical properties of GFRP pipe as well as the soundness of the pipe under buried state. The field test of buried pipe is conducted and the results are analyzed and discussed.

Medium pressure and mixed enzyme were used to hydrolyze raw anchovy under controlled conditions at a batchpilot plant-scale process for the production of anchovy protein hydrolysates (APH). Mass balance calculations were carried out so that the degree of protein solubilization and yields could be estimated. Almost complete hydrolysis could be achieved in 12 h, at 50oC and 75 MPa, with no pH adjustment, at 1% (10 g/kg) mixed enzyme using raw anchovy. This was achieved with the addition of water (1/2 raw anchovy/water). The degrees of protein solubilization and yield were 63.50% and 55.61%, respectively. Fractionation using UF/NF pilot scale systems was carried out for producing four different fractions on the APH. Successive fractionation on UF and NF membranes allowed the concentration of the peptides of selected sizes without, however, carrying out sharp separations, and with some MW classes being found in several fractions. Spray drying processes for 10 kDa permeate were described to increase their usability. The free amino acid profile of the fractions was identical to that of the APH.

A Taguchi robust design method with an L9 orthogonal array and larger-the-better characteristics was implemented to optimize experimental conditions for the hydrolysis of raw anchovy using a pressure-assisted enzymatic reaction method. The degree of hydrolysis (DH), nitrogen recovery (NR) and yield were considered as the response parameters. Pressure, reaction temperature, reaction time, and mixed enzyme amount were chosen as control parameters. As a result of the Taguchi analysis in this study, the pressure was found to be the most influential parameter on DH and NR. The amount of mixed enzyme in the reaction also had a significant effect on DH and NR. Meanwhile, the optimum values were confirmed to be similar at 95% confidence and 5% significance level through analysis of variance (ANOVA). Furthermore, new hydrolysates at optimum conditions and control hydrolysates at atmospheric pressure were compared in terms of the DH, resulting in the improvement of DH by more than 52.6%.

Background: In previous studies regarding flexible pes planus, Foot orthosis, special shoes have been used as interventions for correcting malalignment and intrinsic muscles strengthening exercise have been regarded as interventions for foot function and supporting medial longitudinal arch during walking. However, some recent studies reported that strengthening extrinsic muscles as well as intrinsic muscles is more effective and active intervention for flexible pes planus. In particular, the tibialis posterior muscle of foot extrinsic muscles plays essential roles in maintaining the medial longitudinal arch during dynamic weight bearing and balance. In addition this muscle acts longer than other supination muscles during the stance phase in the gait cycle. Objects: This study aimed to investigate the effect of foot intrinsic muscle and tibialis posterior muscle strengthening exercise for plantar pressure and dynamic balance in adults with flexible pes planus. Methods: 16 young flexible pes planus adults (7 males, 9 females) were recruited and were randomized into two groups. The experimental group performed foot intrinsic muscle and tibialis posterior muscle strengthening training, the control group performed only foot intrinsic muscle strengthening training. All groups received strengthening training for 30 minutes five times a week for six weeks. Results: The experimental group had significantly lower plantar pressure of medial heel area than the control group in stand (p<.05). The experimental group had significantly higher dynamic balance ability than control group (p<.05). Conclusion: The results of this study provide evidence to suggest that foot intrinsic muscle and tibialis posterior muscle of extrinsic muscle strengthening exercises may improve plantar pressure distribution and dynamic balance ability in adults with flexible pes planus.

압력지연삼투(pressure retarded osmosis; PRO) 공정은 염도차가 있는 두 종류의 물과 에너지 변환을 위한 멤브레인과 터빈을 이용하여 에너지를 생산하는 공정이다. PRO용 멤브레인의 전력밀도(W/m2)가 에너지 생산을 위해 가장 중요 하지만, PRO공정에는 멤브레인 외에도 여러 핵심 장비가 존재한다. 따라서, 본 연구에서는 시스템의 경계를 펌프와 터빈 등을 포함하는 영역으로 확장하여 여러 영향 요소들에 따른 순 에너지의 크기를 비교 분석하였다. 결과에 따르면 멤 브레인을 통한 저염도수의 투과율, 저염도수의 유량 분율, 멤브레인 양측의 압력차, 멤브레인 모듈에서 저염도수 측의 압력강하, 모듈의 멤브레인 면적, 에너 지회수장치의 효율 등의 변화에 따라 PRO공정의 순 에너지가 크게 영향을 받았다.

Pressure monitoring is expected to be expanded in a water distribution system according to accelerated development of smart water network management technologies caused by appearances of affordable digital infrastructures like computing, storage and bandwidth. However, the placement of pressure sensors has been determined by engineer’s technical decisions since there is no well-defined criteria for deciding a suitable location of pressure sensor. This study presents a placement method of pressure sensors based on the consideration of allowable error in calibrating water network analysis modeling. The proposed method is to find a minimum set of pressure sensors for achieving a reliable management of water transmissions main and increasing the efficiency of their real-time operation. In the case study in Y area’s transmission main, the proposed method shows equally distributed pressure sensors in terms of hydraulics. It is expected that the proposed method can be used to manage transmission mains stably and construct a robust real-time network analysis system as a minimal criteria.

In this study, ultra-fine soft-magnetic micro-powders are prepared by high-pressure gas atomization of an Fe-based alloy, Fe-Hf-B-Nb-P-C. Spherical powders are successfully obtained by disintegration of the alloy melts under high-pressure He or N2 gas. The mean particle diameter of the obtained powders is 25.7 μm and 42.1 μm for He and N2 gas, respectively. Their crystallographic structure is confirmed to be amorphous throughout the interior when the particle diameter is less than 45 μm. The prepared powders show excellent soft magnetic properties with a saturation magnetization of 164.5 emu/g and a coercivity of 9.0 Oe. Finally, a toroidal core is fabricated for measuring the magnetic permeability, and a μr of up to 78.5 is obtained. It is strongly believed that soft magnetic powders prepared by gas atomization will be beneficial in the fabrication of high-performance devices, including inductors and motors.

국내 시판 중인 선식의 유통 안전성 확보를 위한 기초기반연구로 대기압 플라즈마 처리한 선식의 품질 특성 평가를 진행하였다. 본 연구에서 이용한 플라즈마는 컨테이너형 유전격벽 플라즈마로 방전 가스는 공기를 활용하여 0, 5, 10 및 20분 처리하였고 미생물 감균효과, 색도, pH관능평가를 진행하였다. 일반 호기성 미생물 분석 결과 20분 처리 시 약 1.70 log CFU/g 감소하였으며 B. cereus, B. subtilis 및 E. coli O157:H7을 이용한 접종 시험 결과 각각 2.20, 2.22 및 2.50 log CFU/g 감소하였다. 색도 측정결과 플라즈마 처리에 의해 명도 값은 증가하였으나 적색도 및 황색도는 감소하였다. 플라즈마 처리에 의한 선식의 pH측정 결과 처리시간에 따라 감소하는 경향을 보였다. 하지만 플라즈마 처리에 의해 단백질 지질산화가 일어나 관능 품질이 저하되는 경향을 보였다. 따라서 공기로 방전된 대기압 플라즈마 기술은 선식의 품질안전성을 개선할 수 있으나, 관능적 품질 특성 개선을 위한 후속연구가 필요하다고 판단된다.

This study investigates the thermal shock property of a polycrystalline diamond compact (PDC) produced by a high-pressure, high-temperature (HPHT) sintering process. Three kinds of PDCs are manufactured by the HPHT sintering process using different particle sizes of the initial diamond powders: 8-16 μm (D50 = 4.3 μm), 10-20 μm (D50 = 6.92 μm), and 12-22 μm (D50 = 8.94 μm). The microstructure observation results for the manufactured PDCs reveal that elemental Co and W are present along the interface of the diamond particles. The fractions of Co and WC in the PDC increase as the initial particle size decreases. The manufactured PDCs are subjected to thermal shock tests at two temperatures of 780oC and 830oC. The results reveal that the PDC with a smaller particle size of diamond easily produces microscale thermal cracks. This is mainly because of the abundant presence of Co and WC phases along the diamond interface and the easy formation of Co-based (CoO, Co3O4) and W-based (WO2) oxides in the PDC using smaller diamond particles. The microstructural factors for controlling the thermal shock property of PDC material are also discussed.

도시화로 인해 건축물이 고층화, 밀집화 되면서 건물간의 골바람 효과에 의해 외장재 탈락이나 파손 등의 피해가 발생하고 있다. 골바람 효과에 대한 이전의 연구들은 대부분 구조골조용 풍하중에 중점을 두어 수행되었다. 본 연구는 도심지 골바람 효과에 의해 건축물 외장재의 풍압이 얼마나 증가되는지를 풍동실험을 실시하여 정량적으로 규명하였다. 예비실험을 통하여 골바람이 형성될 수 있는 도심지를 구성하였다. 본 실험을 통하여 형상비와 도로 폭이 변함에 따라 골바람효과에 의해 풍압이 증가하는 특성을 분석하였고, 건축물이 밀집 배치된 경우와 단독 배치된 경우로 나누어 골바람효과로 인한 풍압할증의 정도를 분석하였다. 그 결과 형상비가 커질수록, 도로 폭이 좁아질수록 풍압은 증가하였다. 밀집배치된 건축물의 경우가 단독 배치된 경우에 비하여 풍압이 최대 약 1.8배 증 가하였다. 또한 골바람효과로 인한 풍압의 증가현상은 건물 측벽 전면 하단부에서 가장 큰 것으로 나타났다.

In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate TiO2 powder. The photocatalytic activity of the TiO2 powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused TiO2 cleaned by APDBD improved to a level up to 0.32h- 1 higher than the 30 % value of the initial TiO2 powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which TiO2 effectively adsorbed MB at every photolysis stage.

가압형 정삼투(pressure-assisted forward osmosis, PAFO) 공정은 기존의 정삼투(forward osmosis, FO) 공정의 단 점인 낮은 수투과도 및 유도용질의 역확산을 극복하여 전체 공정 효율을 향상시킨다. 하지만 가압에 의한 추가적인 수리학적 압력의 작용은 파울링을 가속화 시킨다는 단점이 있다. 본 연구는 PAFO의 간헐적 운전방법인 간헐적 가압형 정삼투 (Intermittent pressure-assisted forward osmosis, I-PAFO)의 파울링 저감 가능성을 평가하기 위해 수행되었다. 비교를 위해 FO 및 PAFO를 동시에 운전하여, 세 가지 운전에서의 파울링 거동을 관찰하였다. 파울링 실험을 위한 오염물질로 콜로이드 실리 카 입자를 사용하였고, 분리막 및 입자의 정전기적 상호작용 에너지 변화가 파울링 거동에 미치는 영향도 확인하였다. 실험 결과, I-PAFO 운전에서, 용액 pH 변화에 관계없이 가압구간, 압력완화 구간에서 각각 PAFO, FO보다 높은 수투과도를 유지 하였다. 파울링 실험 후, PAFO에 비해 I-PAFO운전에서 더 적은 수투과도 감소가 관찰되었고, 이로 인해 물리세정 후 향상된 수투과도 회복률 또한 관찰되었다.

The hydrogen embrittlement of two austenitic high-manganese steels was investigated using tensile testing under high-pressure gaseous hydrogen. The test results were compared with those of different kinds of austenitic alloys containing Ni, Mn, and N in terms of stress and ductility. It was found that the ultimate tensile stress and ductility were more remarkably decreased under high-pressure gaseous hydrogen than under high-pressure gaseous argon, unlike the yield stress. In the specimens tested under high-pressure gaseous hydrogen, transgranular fractures were usually observed together with intergranular cracking near the fracture surface, whereas in those samples tested under high-pressure gaseous argon, ductile fractures mostly occurred. The austenitic high-manganese steels showed a relatively lower resistance to hydrogen embrittlement than did those with larger amounts of Ni because the formation of deformation twins or microbands in austenitic highmanganese steels probably promoted planar slip, which is associated with localized deformation due to gaseous hydrogen.

Pay-What-You-Want (PWYW) is an innovative participative pricing strategy in which consumers determine the price they want to pay for a product or service. Past research mainly focuses on individual variables as antecedents of consumers’ willingness to pay under PWYW pricing and ignores the role of situational factors. We address this gap by investigating the effects of three situational factors, perceived crowding, involvement level and time pressure, on consumers’ PWYW pricing decisions. Pay-what-you-want (PWYW) is an innovative pricing mechanism that gives consumers maximum control over the price setting process, and thus allows buyers to entirely determine the price for their desired product or service (Schmidt, Spann & Zeithammer, 2014). The buyer has the authority to choose any price to pay for the offered product or service and there is no minimum price to protect the seller (Kahsay & Samahita, 2015). Such increased perceived control on the final price induces consumers to greater purchase intentions (Chandran & Morwitz, 2005). Hence, a growing number of firms in different industries such as music, museums, software, and charity sales are using PWYW pricing (Schmidt, Spann & Zeithammer, 2014). Internal reference price (IRP) is defined as a price in the buyers' memories that serves as a basis for judging or comparing actual prices (Monroe, 1973; Monroe, Grewal, & Compeau, 1991). In the context of PWYW involvement has a negative effect on prices paid. Involvement is the level of personal relevance consumers possess regarding a product or a purchase decision (Zaichkowsky, 1985). Involvement is conceptualized as both, an individual difference variable representing an “enduring interest” in a given product (Roy, 2015; Bloch & Richins, 1983). It is also posited that the negative effect of involvement on IRP will be further moderated by perceived crowding. Perceived crowding is often described in negative terms as a confined, constrained, and restricted physical setting; and it has two distinct dimensions, spatial crowding and human crowding (Machleit et al., 2000; Byunn & Mann, 2011). A crowded shopping environment is also incompatible with the consumers’ shopping desires and goals; hence consumers exhibit unfavorable shopping behavior such as spend less time in the store (Machleit et al., 2000; Li, Kim & Lee, 2009). Perceived crowding should therefore negatively influence consumers’ involvement and IRP, thereby affecting the money they are willing to pay in PWYW situation.

Background and Purpose of Study: Social commerce refers to a form of electronic commerce based on Social Networking Service (SNS) and has grown substantially since the advent of Groupon in 2008. The growth of social commerce was accelerated with the increased popularity of SNS, where consumers share product information and reviews and the information is spread to others through SNS in real time (KB financial group, 2015). Social commerce can be divided into three types: (1) online group buying, (2) online shopping linked with the SNS, and (3) online shopping in SNS. The first type of social commerce is the most common type in Korea and the current study conducted an experiment based on the online group buying format. In the group buying social commerce, consumers gather together to purchase a product with a cheaper price. Placing a large order facilitates price promotion, (Yuan, & Lin, 2004) and buyers benefit from the cheaper price through the group buying (Zeng, Huang, & Dou, 2009). Group buying websites provides consumers with two types of information: time left for the promotion (time pressure) and the number of product sold (product popularity), and the overall purpose of this study is to examine the effects of time pressure, product popularity and website reputation on purchase intention. Hypotheses Development: Consumers make a purchase on social commerce websites because they can get a product with a cheaper price through group buying. Thus, this study is based on the assumption that all products are under price promotion. According to prospect theory, consumers are more likely to be sensitive to losses than gains. Consumers initially perceive a price promotion as a potential gain, but as the expiration approaches, they are more likely to perceive the promotion as a potential loss, which consequently increase purchase intention (Inman & McAlister, 1994). Also, a statement indicating product popularity, such as ‘the best-selling item’ increases purchase intention (Jeong & Kwon, 2012). Signaling theory provides a useful insight into understanding the effects of website reputation. Since consumers use a website reputation as an indicator of quality (Kirmani & Rao, 2000), they generally respond more positively to well-known websites than unknown websites (Shamdasani, Stanaland, & Tan, 2001). Therefore, based on the literature review, the following hypotheses are developed.H1: High time pressure has a greater impact on purchase intention than low time pressure. H2: High product popularity has a greater impact on purchase intention than low product popularity. H3: Well-known website has a greater impact on purchase intention than unknown website. H4: The effect of time pressure on purchase intention differs as a function of product popularity. H5: The effect of time pressure on purchase intention differs as a function of website reputation. H6: The effect of product popularity on purchase intention differs as a function of website reputation. Method: This study’s design is a 2 (time pressure: high vs. low) x 2 (popularity: high vs. low) x 2 (website reputation: well-known vs. unknown) between-subjects factorial design. This study includes three pretests: (1) to select high versus low time pressure, (2) to select the number of product purchased (product popularity), and (3) to select well-known and unknown social commerce websites. Based on the results of the pretests, eight mock websites simulating social commerce websites were developed for the main experiment. The data were collected via a research company. Invitation emails with a URL were sent to potential participants, and they were guided to shop the website and answer the questionnaire. The measure of purchase intention was adopted from the existing literature with adequate reliabilities (Cronbach’s alpha >.70), and the scale items used a 7-point scale. Manipulation checks showed that manipulations of time pressure, product popularity, and website reputation were successful. Results: A total of 453 female online shoppers participated in the online experiment. An exploratory factor analysis revealed one factor of purchase intention, and the reliability.93, indicating adequate internal consistency of the scale. Hypotheses were tested using analysis of variance (ANOVA). The results showed main effects for product popularity [F (1, 445) = 10.34, p < .05] and website reputation [F (1, 445) = 72.03, p < .05] on purchase intention, supporting H2 and H3. With regard to H4 to H6 predicting interaction effects, ANOVAs showed significant interaction effects of time pressure by product popularity [F (1, 445) = 5.53, p < .05], time pressure and website reputation [F (1, 445) = 4.59, p < .05], and product popularity and website reputation [F (1, 445) = 9.15, p < .05] on purchase intention. Thus, H4 to H6 were supported. Conclusions and Discussion: The study offers academic and managerial implications. The findings of the study provide empirical support for the signaling theory and prospect theory. The results suggest that high popularity and high reputation are significant factors influencing purchase intention. When consumers perceive a product as being popular on a social commerce website, they have greater purchase intention than when they do not perceive the product popularity. Also, when consumers shop on a well-known social commerce website, they have greater purchase intention than when they shop on an unknown website. When the product popularity is high, high time pressure is an important factor enhancing purchase intention. When a website is well-known, high time pressure increased purchase intention. However, when a website is unknown, high product popularity increased purchase intention. These findings of the study contribute to the literature in social commerce. Based on the website reputation, social commerce websites need to incorporate appropriate marketing tactics, such as time pressure and product popularity to increase consumers’ purchase intention.