• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.854-855
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• 2013

As an unique acoustic characteristic of a Korean bell. beat phenomenon is a periodic repetition of strong and weak sounds. Beat sounds good when it is clear and it has a proper period, however, it is not easy to satisfy these two conditions simultaneously. In this study, we propose a beat tuning method to satisfy these two conditions, by using an equivalent bell model. First, we construct an equivalent bell which has the same beat property with the 1st beat of a real bell and we investigate the change of mode pair by finite element analysis, when thickness of the bell is locally decreased at $22.5^{\circ}$ from the striking point. From the analysis result, minimum thickness reduction amount is determined to make a clear and strong beat.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.708-712
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• 2013

The appearance of the Korean bell is exceptional comparing to that of other bells. The sound of the Korean bell is also distinguishable because of its remarkable appearance. The sound of the Korean bell is composed of striking sound and residue sound. This study focuses mainly on the striking sound of the Korean bell. The primary purpose of this study is to suggest a proper sound quality evaluation method for Korean bell. To implement this study, examine the formerly established methods which are method using rating method and method using generally used Psychoacoustics metrics. Also, subjective Sound Quality evaluation was conducted to compare the results of method using rating method and the method using psychoacoustics metrics.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.324-330
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• 2012

Dual bell nozzle is one of the most promising choices among the altitude adaptation nozzles. This facilitates having a forced, steady and symmetrical separation at lower altitudes and a controlled flow separation at the wall inflection point which prevents the generation of dangerous side loads. In order to ensure the attached flow in the second bell, a clear understanding of the flow transition is required. Hence the motivation of our study is to arrive at an optimum profile for the second bell, which allows a sudden and controlled transition. In this work, we designed the first bell using the conventional MoC and the second bell using an inverse MoC, imposing a pressure gradient constraint. A CFD analysis is also carried out. It is found that the separation point is near the inflection point within one fourth of the extension length or it is near the exit.

• Nonlinear Functional Analysis and Applications
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• v.26 no.4
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• pp.733-747
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• 2021

Recently, Kim-Kim introduced Lah-Bell polynomials and numbers, and investigated some properties and identities of these polynomials and numbers. Kim studied Lah-Bell polynomials and numbers of degenerate version. In this paper, we study degenerate Lah-Bell polynomials arising from differential equations. Moreover, we investigate the phenomenon of scattering of the zeros of these polynomials.

• Journal of Korea Multimedia Society
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• v.18 no.8
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• pp.968-979
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• 2015

In this paper, we study a vibration bell App which shows waiting sequence numbers by utilizing smartphones to solve an inconveniently long waiting time from ordering to getting foods in restaurants and coffee shops. Unlike existing independently developed hardware and software, the vibration bell App is developed to manage and integrate customer management service, POS service in shops, and group shop management services. The functions of the vibration bell App include two-way communications based on NFC- issuing waiting sequence numbers and electronic coupon, showing event information, and transferring user information. Furthermore, the user's personal information is minimized by recognizing the pre-existing information of the user's smartphone. Replacing the shop's vibration bell system with the vibration bell APP, the shops can reduce the cost of construction and maintenance by up to 1/10, compared to the cost of for existing vibration bell systems. Moreover, the customer's preference and current sales trend can be easily figured out. Thus, it will have a great effect on the future marketing strategies.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.8
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• pp.626-636
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• 2003

The beat distribution property of the King Seong-deok Divine Bell is investigated by experiment and analysis. The beat map method is proposed to explain the beat distribution property on the circumference of the bell. For the analytical investigation, an analytical model of the vibration beat is derived on a slightly asymmetric shell of revolution by using the modal expansion method. In the analytical method, the beat map can be drawn only if the modal parameters of the bell are obtained. The analytical beat model is applied to draw the beat map of the King Seong-deok Divine Bell. The validity of the analytical method is verified by comparing the analytical beat maps with the experimental results. This paper proposes a visualization method of the beat and theoretically identifies the reason why the clear and unclear beats repeat periodically along the circumference of the bell and how the striking position influences the beat distribution property.

• The Journal of the Acoustical Society of Korea
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• v.2 no.1
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• pp.1-10
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• 1983

The presence of the sound tube and resonance cavity is unique in Korea Brahman Bells which is no examples in other country bells in the world. The sound tube erected in the crown is effective to emit the fundamental tone of the bell when the condition of resonant transmissibility is satisfied. The results of our analysis shows that the optimum length of the sound tube in the Bell Emile is 96cm but is not the present length, 77cm. The resonance cavity erected underneath the lip of the Bell Emile is found to be for the resonance of standing waves in the space including both bell cavity and resonance cavity and resonance cavity to the fundamental tone of the bell itself, in order that the strongest vibration can last long by least energy and lengthen the reverberation of the bell. Some historical remarks are also made on the magic flute, MANPASIKJUK, which was in existence in Shilla that can lull all evil waves, such as plagues, storms, droughts, famines and even enemies. The sound tube erected in the crown of the bell was originated in this magic flute. Finally, a strong proposal is advanced on the new national symbol of Korean traditional cultural assets. Indeed, it should be highly recommended that the Great King's Bell Emile would be the only real symbol of our national cultural assets by its own right of excellency and richness in every aspect of arts and sciences.

• Journal of the Korea Fashion and Costume Design Association
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• v.19 no.1
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• pp.91-105
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• 2017

A literature review and survey were conducted regarding the silhouette changes in bell bottom pants and the overall visual evaluation in accordance with the changes. The survey was disseminated from December 2015 to January 2016 to 245 women in their 20s living in Busan. The variables used for the silhouette changes in bell bottom pants were the volume of flare and the flare's starting point, and 20 pairs of terms were selected for visual evaluation. The results of the study are as follows: 1. Visual evaluations according to the volume of flare in bell bottoms indicated that females in their 20s appraised pants with a flare volume of 54 cm close to a straight silhouette and flare volume of 62 cm (recognized clearly as characteristic of bell bottom pants) to be more attractive and sophisticated than pants with flare volumes of 70 cm and 78 cm. 2.Visual evaluations according to the starting point of the flare in bell bottom pants showed that women appraised their legs as looking thinner when the flare started near the thighs. In a vertical visual evaluation, women appraised that their legs looked longer when the flare started near the knees and pants fit tightly around them. 3.The analysis of silhouette factors affecting the visual evaluation of bell bottom pants indicated that the volume of flare has more effect visually than the starting point of the flare.

• The Journal of the Acoustical Society of Korea
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• v.30 no.4
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• pp.223-230
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• 2011

Korean bell is hung with some air gap between the bell bottom and the ground. In addition, it has a peculiar acoustic element, so called resonance cavity below the bell. A proper design of the air gap and cavity size dramatically amplifies the bell sound by resonance effect. Bell interior cavity, air gap and resonance cavity consist of an acoustic cavity system. When the acoustic cavity frequency coincides with the natural frequency of the bell body, the frequency component is significantly amplified. On the Sacred Bell of the Great King Seongdeok, this study proposes a resonance condition of the cavity system considering air gap effect for the first time. With the exact dimension of the bell, boundary element analysis is performed using SYSNOISE. Finally, this study reveals how the temperature in season influences the resonance condition and proposes a concept of variable type resonance cavity. By using the variable type resonance cavity, the cavity size is controlled on site and exact resonance is available regardless of temperature difference in season.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.176-183
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• 2020

A ship has three types of diving systems (Diver Stage Diving, Wet Bell Diving and Scuba Diving) to carry out a search-and-rescue operation. To reduce the possibility of decompression sickness, any diving systems shall comply with the decompression procedure according to the decompression table corresponding to the diving depth and diving time. The decompression procedure is largely divided into two methods: underwater decompression and underwater-onboard decompression. In particular, the surface interval shall not exceed 5 minutes, which is the phase from underwater decompression to underwater-onboard decompression, in accordance with the U.S Navy Diving Manual. However, the surface interval is greater than 5 minutes as a result of using Wet Bell Diving. This paper describes the result of cause analysis and measurement with improved Wet Bell Diving. Using improved Wet Bell Diving reduced the surface interval to less than 5 minutes. The result of the research can be used for operation and improving the performance of diving systems.