Background: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS). Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs). Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954–0.971) and inter-day (ICC = 0.865–0.937) values, standard error of measurement (SEM) values (1.05°–2.04°), and minimal detectable change (MDC) values (2.92°–5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity. Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

In this study, we analyzed the whole design of the necklace in detail, which reflects the artistic sense of handicraft in couture. The purpose of the study was to identify the characteristics of the design based on the analysis findings and to provide basic data to help fashion designers. The research method entailed analyzing trends in necklace design - viewed in fashion magazines and on websites - by year, season, brand, kind, material, color, and image. The identified necklace design characteristics were as follows. First, artistry and originality are dramatically expressed through the use of a broad range of materials. Second, due to the necklace’s role as an object of perfect beauty, in a number of images, the necklaces were presented in convergence and contrast with overall costumes. Third, the dramatic effects of layering revealed a strong presence and individualized styling. Necklaces are created with diverse sculptures by realizing the creative imagination of fashion designers. Even though they looked a little different every year, there were designs in the collections constantly. Round shape and princess length were preferred. In particular, the mix type was used to express dramatic effect by focusing neck part in entire styling which different length of necklaces were layered and worn. As a result, it meets the needs of consumers who emphasize brand differentiation and diversity, and it is believed that the role of necessities in fashion will continue and it creates economic demand in the fashion industry.