• 대한기계학회논문집B
• /
• 제23권1호
• /
• pp.58-68
• /
• 1999

The entry compression wave, which forms at the entrance of a high-speed railway tunnel, is closely related to the pressure transients in the train/tunnel systems as well as an impulsive noise appearing at the exit of the tunnel. In order to alleviate such undesirable phenomena, some control strategies have been applied to the compression wave propagating inside the tunnel. The objective of the current work is to investigate the effect of tunnel entrance hoods on the entry compression wave at the vicinity of the tunnel entrance. Three types of entrance hoods were tested by the numerical method using the characteristics of method for a wide range of train speeds. The results show that the maximum pressure gradient of compression wave can be considerably reduced by the tunnel entrance hood. Optimum hood shape necessary to reduce the pressure transients and impulsive noise was found to be of an abrupt type hood with its cross-sectional area 2.5 times the tunnel area. It is believed that the current results are highly useful in predicting the effects of entrance hoods and in choosing the shape of proper hood.

• 대한기계학회논문집B
• /
• 제23권2호
• /
• pp.234-242
• /
• 1999

Flow phenomena such as the pressure transients Inside a high-speed railway tunnel and the Impulsive waves at the exit of the tunnel are closely associated with the characteristics of the entry compression wave, which is generated by a train entering the tunnel. Tunnel entrance hood may be an effective means for alleviating the Impulsive waves and pressure transients. The objective of the current work is to explore the effects of the train nose shape and the entrance hood on the characteristics of the entry compression wave. Numerical calculations using the method of characteristics were applied to one-dimensional, unsteady, compressible flow field with respect to high-speed railway/tunnel systems. Two types of the entrance hoods and various train nose shapes were employed to reveal their influences on the entry compression wave for a wide range of train speeds. The results showed that the entry compression wave length increases as the train nose becomes longer and the train speed becomes lower. The entry compression wave length in the tunnel with hood becomes longer than that of no hood. Maximum pressure gradient in the compression wavefront reduces by the entrance hood. The results of the current work provide useful data for the design of tunnel entrance hood.

• 한국통신학회논문지
• /
• 제36권8C호
• /
• pp.516-521
• /
• 2011

이 논문에서는 심각한 다중경로 페이딩 왜곡과 충격성 잡음을 극복하기 위해 결정궤환 구조를 갖추고 오차의 영확률을 최대화하는 비선형 알고리듬(MZEP-DF)를 제안하였다. 제안된 MZEP-DF 알고리듬은 충격성 잡음에 강인성을 보였고 궤환구조 영역에서 잔여 심볼간 간섭을 제거하는 능력을 보였다. 기존 LMS 알고리듬이 정상상태 오차 전력에 대해 -3 dB 이하로 수렴하지 못했던 심각한 다중경로 페이딩과 충격성 잡음 환경에 대해 제안한 알고리듬은 선형 MZEP 알고리듬과 비교하였을 때, 10 dB 이상 성능향상을 보였다.

• 한국해양공학회지
• /
• 제16권6호
• /
• pp.7-17
• /
• 2002

Recently, artificial rocks, instead of buoys, have been placed on the submerged breakwater to indicate its location. The accurate estimation of wave forces on these rocks is deemed necessary for their stability design. Characteristics of the wave force, however, are expected . to be very complicated because of the occurrence of breaking or post-breaking waves. In this regard, wave forces exerted on an artificial rock have been investigated in this paper. The maximum wave force has been found to strongly dependent on the location and shape of the artificial rock that is placed on the submerged breakwater. The plunging breaker occurs near the loading cram edge of a submerged breakwater, which cause impulsive breaking wave force on the rock. Using the Morison equation, with the velocity and acceleration at the front face of the artificial rock and varying water surface level, it is possible to estimate wave forces, even impulsive breaking wave forces, that are acting on the rock installed on a submerged breakwater. The vertical wave force is also found to depend, significantly, on the buoyant force.

• 대한기계학회논문집
• /
• 제19권8호
• /
• pp.1972-1981
• /
• 1995

As a railway train enters a tunnel at high speed, a compression wave is formed in front of the train and propagates along the tunnel. The compression wave subsequently emerges from the exit of the tunnel, which causes an impulsive noise. The impulsive noise is closely related to the pressure gradient of the compression wave propagating the tunnel. In order to investigate the characteristics of the compression waves, in the present study an experiment was made using a shock tube. The results show that the strength of a compression wave decreases with the distance from the tunnel entrance and the nonlinear effect of compression wave appears to be significant if strength of the initial compression wave is greater than 7 kPa. Furthermore if the wave pattern is known, attenuation of the compression wave propagating in a tunnel can be reasonably predicted by a theoretical equation considering viscous action and heat transfer in boundary layer.

• 한국소음진동공학회논문집
• /
• 제15권3호
• /
• pp.272-279
• /
• 2005

이 논문에서는 프로토타입(prototype) 고충격력 기구에 대한 최적의 절연시스템이 연구된다. 이 목적을 위해 첫째, 고충격력 기구의 특정한 작동조건하에서 인체의 거동과 전달력이 고안된 시험 장치를 이용한 실험을 통해 분석된다. 최적 동흡진기를 설계하기 위하여, 파라미터 최적과정이 충격량과 전달력의 실험결과를 토대로 한 단순화된 절연시스템 모델을 사용하여 이루어진다. 최종적으로, 충격완화 변위와 전달력의 구속조건을 만족시키는 파라미터 하에서, 프로토타입 고충격력 기구에 대해 최적 설계된 절연시스템의 성능이 실험에 의해 평가된다.

• 복식문화연구
• /
• 제28권3호
• /
• pp.313-329
• /
• 2020

Social Network Services (SNS) have become a vital means of shopping, significantly influencing consumers' purchases of fashion products. The aim of this study was to identify bandwagon consumption among fashion consumers and to analyze the effects of bandwagon consumption on negative emotions, purchase discontinuation, and switching intention. A survey questionnaire was developed, and data were obtained from 285 female consumers in Korea aged in their 20s and 30s who had experienced guilt, regret, or disappointment after purchasing fashion products using SNS during the previous six months. The survey results indicated four different types of band- wagon consumption: intentional, impulsive, unintentional, and planned. The presence of negative emotions such as guilt, disappointment, and regret were affected by different types of bandwagon consumption. Intentional bandwagon consumption only affected guilt, while unintentional bandwagon consumption affected both guilt and disappointment. Impulsive bandwagon consumption affected guilt and regret; however, planned bandwagon consumption only affected regret. Furthermore, negative emotions affected purchase discontinuation and switching intention. Planned bandwagon con- sumption had an effect on both purchase discontinuation and switching intention, while both impulsive and unintentional bandwagon consumption influenced switching intention only. Intentional bandwagon consumption had no effect on either purchase discontinuation or switching intention. The results of this study indicate that SNS consumers' bandwagon consumption causes different negative emotions, purchase discontinuation, and switching intention.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2008년도 추계종합학술대회 B
• /
• pp.663-668
• /
• 2008

본 논문에서는 임펄스 잡음 환경에서 길쌈 부호화 기법을 채용한 16 QAM 신호의 오율 성능을 분석하였다. 성능 개선을 목적으로 길쌈 부호화 기법과 최대비 합성 다이버시티를 사용하였다. 임펄스 잡음과 가우시안 잡음의 환경에서의 비교 분석을 통해서 임펄스 잡음과 가우시안 잡음의 특성에 따른 신호의 성능을 해석할 수 있다. 분석의 결과로서 임펄스 잡음 환경에서는 신호 전력을 높여주어도 오율 성능이 향상되지 않는 Error floor 구간이 있으며, 이 한계를 넘는 신호 전력이 제공되어야지만 오율 성능이 개선됨을 확인할 수 있다.

• 한국의류산업학회지
• /
• 제18권2호
• /
• pp.158-166
• /
• 2016

This study investigates the impact of fashion product attributes and mobile shopping mall attributes on impulse buying behavior and mobile shopping satisfaction. The findings provide new information to marketers on marketing strategy for mobile shopping malls. We obtained 283 usable questionnaires from college students. Data were analyzed by frequency analysis, correlation analysis, factor analysis using SPSS for Window 21.0 and confirmatory factor analysis and structural equation model analysis by AMOS 21.0. The results were as follows. The utility of fashion products attributes had the greatest impact on impulse buying behavior when buying fashion products in a mobile mall. Utility had a negative effect on impulsive buying behavior and exhibitionistic had a positive effect on impulsive buying behavior. Next, continuous management of mobile shopping mall attributes influenced impulse buying behavior. In addition, impulse buying behavior showed that the positive effect on satisfaction. Fashion product attributes had a greater impact on impulsive buying behavior than mobile mall properties when buying fashion products in the mobile mall; in addition, impulse buying facilitated customer satisfaction.

• 한국의류학회지
• /
• 제20권3호
• /
• pp.414-428
• /
• 1996

This study intends to ascertain the importance of store atmosphere when construcing store marketing strategies for store differentiation. And it is studied by classifying consumer groups according to clothing shopping motivations, comparing store atmosphere assessment and emotion response of preferred stores, and analyzing the influence store atmosphere has on store preference or impulsive purchase. The subject of this study are women in their twenties living in Seoul, 255 career women and 233 college students totaling 458, and model sampling is done by convenient sampling taking into account the type of their occupation and major. Modified survey based on references and former studies is used, and using SAS packages, methods. The results of data analysis are as follows. 1. Consumer groups are classified into the following four subdivisions: shopping involvement, leisure pursuit, financial, and shopping unconcern group. The stores women in twenties use most frequently for shopping are department stores, speciality stores, common market, discount stores, and wholesale markets, and significant difference are shown between consumer groups. 2. Consumer responses for store atmosphere preferences are shown significantly among groups when concerned with store preferences. 3. Images of store atmosphere as factor analyzed into environment factor, kindness factor, and decoration factor, Environment factor is most highly estimated in speciality stores, kindness factor in department stores, and decoration factor in common markets. 4. Leisure pursuit group is assessed to be most influenced by store atmosphere in store seleciton, impulsive purchase, and after-purchase shopping behavior, and impulsive purchase is shown highly in department stores and speciality stores.