Machines and facilities are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. The representative type of the degeneration is wear of tool or machine. According to the increasing wear level, non-conforming products cost and quality loss cost are increasing simultaneously. Therefore a periodic preventive resetting the process is necessary. The total cost consists of three items: adjustment cost (or replacement cost), non-conforming cost due to product out of upper or lower limit specification, and quality loss cost due to difference from the process target value and the product characteristic value among the conforming products. In this case, the problem of determining the adjustment period or wear limit that minimizes the total cost is called the ‘process mean shift’ problem. It is assumed that both specifications are set and the wear level can be observed directly . In this study, we propose a new model integrating the quality loss cost, process variance, and production volume, which has been conducted in different fields in previous studies. In particular, for the change in production volume according to the increasing in wear level, we propose a generalized production quantity function g(w). This function can be applied to most processes and we fitted the g(w) to the model. The objective equation of this model is the total cost per unit wear, and the determining variables are the wear limit and initial process setting position that minimize the objective equation.

In this study, the formation, microstructure, and wear properties of Colmonoy 88 (Ni-17W-15Cr-3B-4Si wt.%) + Stellite 1 (Co-32Cr-17W wt.%) coating layers fabricated by high-velocity oxygen fuel (HVOF) spraying are investigated. Colmonoy 88 and Stellite 1 powders were mixed at a ratio of 1:0 and 5:5 vol.%. HVOF sprayed selffluxing composite coating layers were fabricated using the mixed powder feedstocks. The microstructures and wear properties of the composite coating layers are controlled via a high-frequency heat treatment. The two coating layers are composed of γ-Ni, Ni3B, W2B, and Cr23C6 phases. Co peaks are detected after the addition of Stellite 1 powder. Moreover, the WCrB2 hard phase is detected in all coating layers after the high-frequency heat treatment. Porosities were changed from 0.44% (Colmonoy 88) to 3.89% (Colmonoy 88 + ST#1) as the content of Stellite 1 powder increased. And porosity is denoted as 0.3% or less by inducing high-frequency heat treatment. The wear results confirm that the wear property significantly improves after the high-frequency heat treatment, because of the presence of wellcontrolled defects in the coating layers. The wear surfaces of the coated layers are observed and a wear mechanism for the Ni-based self-fluxing composite coating layers is proposed.

Despite the declining birth rate and consequent lower children population in Korea in recent years, there has nevertheless been found to be a positive trend in relation to the purchase of toddler and children’s wear. This has led toddler and children’s wear to pursue sales and marketing strategies. There is especially a growing number of experiential marketing that provide an empirical element, which stimulate consumers’ emotions, and also create a relationship with a brand. Therefore, this research aims to serve as practical data for the planning and implementation of experiential marketing strategies through the analysis of experiential marketing cases conducted by brands of toddler and children’s wear. The study examines the status of the Korean toddler and children’s fashion market between 2009 and 2018. The domestic brands of toddler and children’s wear were analyzed with the application of Bernd H. Schmitt’s five experiential modules. The analysis results first showed that of the five modules, ‘feel’ held the highest proportion, followed by ‘think’ and ‘act’, and lastly ‘sense’ and ‘relate’. Second, the experiential marketing stimulated more than three of the five senses. Third, experiential marketing that provided educational experiences to children was conducted. Fourth, an experience was provided for parents and children to enjoy together. Finally, product promotion and purchase were naturally linked. The study’s results have confirmed that toddler and children’s wear brands implement experiential marketing strategies, which convey the emotional and cultural experiences shared by parents and children in various ways.

As the spread of the health and wellness trend continues worldwide, many consumers are spending much time on sports activities and expressing their individuality through sportswear. This study analyzes the trade networks of major exporters and importers of athleisure wear to provide an exporting policy for Korean apparel companies. As a result, The USA was found to import the most athleisure wear. On the other hand, China had the largest number of athleisure wear exports, and India’s exports, which are becoming increasingly important as apparel producers were notable. Next, using the concept of the centrality of social network analysis, it was found that the USA was the largest importer and the center of athleisure wear’s export network, but its influence has decreased gradually since 2010. China has the highest out-degree and betweenness centrality and center in the export of athleisure wear. The centrality of Asian countries such as India and Vietnam has increased. In Korea, the import of athleisure wear has increased greatly, but the export of athleisure wear has continuously decreased. Korea has less price competitiveness than other developing countries in Asia, but many Korean athleisure wear clothing brands are now attracting popularity not only in Korea but also in other countries with their excellent technology and design. In the future, the exporting policy of Korea’s athleisure wear should focus on high value-added and differentiated products.

목적 : 근시 교정을 위한 라섹수술안과 소프트 콘택트렌즈 착용안에서 고위수차에 의한 시력의 질을 비교 평가하였다. 방법 : 라섹수술안 40명의 80안, 콘택트렌즈 착용자 20명의 40안, 정시안 19명의 38안을 대상으로 하였다. 단안의 나안 시력 1.0 이상이 대상자의 기준이 되었다. 밝은 조명과 어두운 조명 상태에서 고대비와 저대비시력 검사 및 대비감도 검사를 시행하였다. 파면수차 분석기(KR-1W, Topcon)를 이용하여 4 mm와 6 mm 동공 크기에 따라 눈의 고위수차를 측정하였다. 결과 : 밝은 조명상태에서 고대비시력과 저대비시력은 서로 다른 시력교정 방법에 따라 정시안과 통계적인 차이가 없었으나, 어두운 조명상태에서는 세 그룹 사이에서 고대비시력과 저대비시력은 각각 통계적으로 유의한 차이가 있었다(고대비시력; p=0.031, 저대비시력; p=0.025). 대비감도는 밝은 조명과 어두운 조명상태 모두에서 3cpd 를 제외한 6, 12, 18cpd 공간주파수에서 라섹수술안과 소프트렌즈 착용안사이에 통계적인 차이가 있었다(6cpd; p=0.000, 12cpd; p=0.000, 18cpd; p=0.000). 고위수차는 4 mm와 6 mm 동공 크기 모두 두 그룹사이에서 통계적으로 유의한 차이가 나타났다 (전체고위수차; p=0.000, 코마수차; p=0.000, 구면수차; p=0.000). 결론 : 라섹수술안, 소프트렌즈 착용안 및 정시안은 밝은 조명상태에서는 시력의 질의 차이가 나타나지 않지만 동공의 크기가 커질수록 증가하는 라섹수술안의 고위수차량은 밤 동안에 시력의 질에 영향을 미칠 것으로 생각된다.

본 연구에서는 수면무호흡증이 다양한 합병증을 유발하는 질병으로서, 이를 위한 표준화된 수면다원검사가 고가 이며 측정이 불편함을 고려하여, 환자가 익숙한 환경에서 검사를 받을 수 있도록 스트레치 섬유센서를 이용한 무구 속 상태의 웨어러블 모니터링 시스템을 개발하고자 한다. 또한, 의복과 일체화된 디자인으로 제품화하여 그 유용성을 제안하고자 한다. 성인 남성용 롱 슬리브 티셔츠 형태로 착용형 수면무호흡 모니터링 스마트 의류를 개발하여, 수면무호흡 진단 지표 중 섬유형 센서를 기반으로 측정하는 호흡수(breathing rate)측정용 섬유센서, 산소포화도 (oxygen saturation), 호흡기류(airflow)를 실시간 측정하였다. 최적의 조합비 샘플 4가지를 통한 gauge factor를 측정한 결과, gauge factor 20.3을 확인하였고, 3회 숨을 크게 내쉴 때 호흡유량이 최대 2048ml였다. 산소포화도 69.45% 로 최소 측정 가능 산소포화도 70% 정도의 결과를 나타내었다. 세탁 후 인장에 따른 센서 성능 평가 결과는 전체적으로 gauge factor 18 수준의 값으로, 세탁에 대한 내구성이 입증되었다. 본 연구를 통하여 수면무호흡증 환자의 수 면효율이 떨어지고 여러 합병증을 동반하는 문제에 대해, 가정에서 쉽게 사용할 수 있는 착용형 수면무호흡 모니터 링 스마트 의류를 개발하여 호흡수, 호흡유량, 산소포화도의 3가지 지표를 측정 가능함을 확인하였다.

The purpose of this study was to investigate the effect of perceived risk, community usage motive, and price sensitivity of customers who purchase children’s wear directly from overseas on customer satisfaction. Specifically, this study is aimed at verifying the moderating effect of price sensitivity when perceived risk and community usage motive significantly influence customer satisfaction. A survey was conducted among consumers who experienced directly purchasing children’s wear from overseas and engaging in communities. A total of 415 questionnaires were distributed, which 41 responses were insincere and excluded; thus, 374 responses were analyzed. Results of this study are as follows. First, the analysis on how perceived risk and community usage motive influence customer satisfaction reveals the significant influence of economic and social psychological risk on customer satisfaction. Moreover, informational, recreational, and social emotional usage motive have a significant influence on customer satisfaction. Second, the effect of perceived risk and community usage motive on customer satisfaction based on different levels of price sensitivity was verified. As a result, delivery and economic risks affect customer satisfaction for consumers with high price sensitivity. Moreover, recreational usage motive has a significant influence on customer satisfaction for high price sensitive consumers. In conclusion, perceived risk negatively impacts customer satisfaction. Therefore, it is essential to provide a system that can reduce the perceived risk of consumers who purchase children’s wear directly from overseas.

This study investigates the microstructure and wear properties of cermet (ceramic + metal) coating materials manufactured using high velocity oxygen fuel (HVOF) process. Three types of HVOF coating layers are formed by depositing WC-12Co, WC-20Cr-7Ni, and Cr3C2-20NiCr (wt.%) powders on S45C steel substrate. The porosities of the coating layers are 1 ± 0.5% for all three specimens. Microstructural analysis confirms the formation of second carbide phases of W2C, Co6W6C, and Cr7C3 owing to decarburizing of WC phases on WC-based coating layers. In the case of WC-12Co coating, which has a high ratio of W2C phase with high brittleness, the interface property between the carbide and the metal binder slightly decreases. In the Cr3C2-20CrNi coating layer, decarburizing almost does not occur, but fine cavities exist between the splats. The wear loss occurs in the descending order of Cr3C2-20NiCr, WC-12Co, and WC-20Cr-7Ni, where WC-20Cr-7Ni achieves the highest wear resistance property. It can be inferred that the ratio of the carbide and the binding properties between carbide–binder and binder–binder in a cermet coating material manufactured with HVOF as the primary factors determine the wear properties of the cermet coating material.

본 연구는 고령에 접어들고 있는 베이비부머 집단의 보행 운동용 스마트 스포츠웨어 및 스포츠 애플리케이션에 대한 수용태도를 분석하고 베이비부머 집단의 특성에 맞는 스마트 워킹웨어 및 연동 애플리케이션 개발방향을 제시하는 것이다. 연구 방법은 조사연구로 설문지법을 사용하였으며 측정 도구는 기존 스마트 스포츠웨어와 스포츠 애플리케이션의 디자인, 기능성 사용성에 대한 수용태도를 묻는 문항 등으로 구성되었으며, 조사대상은 50세 이상 65세 미만의 베이비부머 집단을 대상으로 진행됐다. 연구결과를 요약하면 다음과 같다. 베이비부머 소비자들은 스 마트 스포츠웨어의 기능 및 성능안전성에 대해 긍정적으로 인식하나 관리 및 내구성에 대한 우려가 있어 스마트 스포츠웨어의 내구성 및 편의성 개선방향 및 사후 처리에 대한 고려가 필요하다. 스포츠 애플리케이션의 경우 새로운 정보를 얻을 수 있는 교육적인 기능으로 인식하며, 인지용이성 및 접근성에 대해 젊은 세대에 비하여 어려움을 느끼는 것으로 나타났다. 본 연구 결과를 바탕으로 베이비부머 소비자의 보행운동용 워킹웨어의 디자인 및 기획 방향으로는 ‘일반 스포츠웨어 디자인의 일상적 디자인’, ‘소비자의 선호가 반영된 기능’, ‘관리의 편의성 및 내구성을 높인 디자인’ 등을, 보행운동용 애플리케이션의 기획 방향으로는 ‘쉬운 스포츠 애플리케이션 구성’, ‘교육적 운동 콘텐츠 구성’ 등을 제시하였다.

In this study, the amount of abrasive wear was predicted effectively by FE simulation and experiment regarding the material and shape of the abrasive. In order to calculate numerically the amount of wear using the Archard wear equation, the normal load between the abrasive and the polyurethane was calculated by FE simulation. The sliding distance can be calculated according to the working conditions, and the hardness of the polyurethane is a known value. The wear coefficient K was calculated inversely by experimental measurement of the wear amount according to the working conditions of the abrasive. In order to verify the proposed calculation method, the wear amount was calculated by using the Archard wear equation by applying the calculated wear coefficient K with regard to arbitrary working conditions. The deviation between the proposed calculation results and the experimental results was within 10%. When the wear coefficient K is calculated by using the proposed method, the wear amount can be estimated. In addition, it was found that the change of the vertical load value concerning penetration depth was the main factor for determining wear amount.

As product diversity increases and product life cycle gets shorter, lead time reduction and manufacturing cost saving of die & mold are getting important in machinery, automotive, and electronics industries. To develop a novel free-machining die & mold steel, we try to modify the chemical compositions of AISI P20 mold steel by adding boron, nitride, and sulfur. After making three types of mold steels which are base metal of AISI P20 mod., boron and nitrogen added, and boron, nitrogen, and sulfur added to the base metal. Milling tests are carried out using TiN, TiCN, and TiAlN coated WC end-mills under various cutting conditions. Boron and nitrogen added steel machined by TiN coated tool shows the most excellent tool wear and surface roughness characteristics. The results might come from BN inclusions in base metal acting as a stress concentration source and lowering strain resistance during cutting process. The relationship between tool wear and surface roughness are also discussed including feed rate effects.