• 한국항공우주학회지
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• 제48권7호
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• pp.497-504
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• 2020

초음속 비행으로 인해 발생하는 소닉붐을 해석하여 소닉붐의 소음 강도와 대기 전파 특성에 예측할 수 있는 기법을 개발하였다. 소닉붐은 환경 문제를 유발하므로 지상에서 계측되는 소음 강도가 매우 중요한데 본 연구에서는 개략 분석 기법을 이용하여 비행체의 물리량과 비행 정보로부터 계측지 거리에 따른 음압을 산출하였다. 소닉붐의 지상 계측을 위해 비행체에서 발산되는 충격파의 대기 전파 특성을 예측해야하며 이를 위해 시선벡터법과 음선추적기법을 이용하였고, 대기 밀도의 고도별 분포에 따른 굴절을 고려하였다. 개발된 기법을 이용하여 실제 초음속 비행체의 소닉붐을 예측하였고 측정결과와 잘 일치하였다.

• 대한소아치과학회지
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• 제45권2호
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• pp.144-153
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• 2018

본 연구는 치근 및 치주조직의 형성과정동안 Sonic Hedgehog (SHH) signaling의 역할에 대해 알아보고자 치성간엽에서 조직특이적으로 Smoothened (Smo)가 활성화 또는 차단되는 mouse를 제작하여 분석하였다. 생후 28일경 Smo 활성화모델에서는 H-E 염색 시 얇은 두께의 치근상아질, 넓어진 치수강, 치주인대공간에 느슨하게 배열되어있는 섬유들이 관찰되었다. 면역조직화학염색 시 Smo 활성화모델은 wild type mouse와 비교하여 백악질, 치주인대 그리고/또는 백악모세포의 표식자인 Bsp, Dmp1, Periostin, Ank 같은 기질 단백질들의 발현이 현저히 감소하였다. 그러나 Smo 차단모델은 wild type mouse와 비교하여 이러한 기질 단백질들의 발현에 차이가 보이지 않았다. 본 연구를 통하여 치근 및 치주조직의 정상적인 형성과정에 낮은 수준으로 조절되는 SHH signaling이 필요하다는 것을 확인할 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.383-387
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• 2001

본 논문은 여러 형태의 해저 침전물인 뻘, 모래, 자갈, 패류 등을 초음파를 이용하여 구별하는 것인데, 이는 해저목표물에 대한 신호패턴 데이터베이스를 구축한 후, 기존 어군탐지기로부터 아날로그 신호를 디지털 신호로 변환하고, 이 신호를 컴퓨터에서 가공하여 정확한 목표물 인식이 가능하도록 하는 판독시스템을 개발하는 것이다. 지금까지 연구한 결과를 바탕으로 많은 실험을 거친 후(수조 및 현장 실험 등) 침전물의 데이터를 정밀 분석하면 해저목표물을 알아낼 수 있다. 수중에서 어종별로 어체에서 반사되는 초음파 특성과, 해저면에서 뻘과 딱딱한 패류 껍질, 모래 자판 등에서 반사되는 초음파 특성 등을 분석한 값을 데이터베이스화하여 저장해 두고, 실제 측정시 해저 목표물로부터 반사 되어오는 값과 비교하여 침전물과 어·패류의 서식 상태 현황을 파악하는데, 이런 어·패류 판독용 초음파 탐지기는 된 연구를 통하여 개발 할 수 있다. 중점적으로 추후 연구해야 할 분야는 초음파의 특성을 더욱더 세밀히 샘플링 하는 것과 초음파가 해저 목표물의 여러 형태에 따라 산란 특성을 가지고 있는데 이들에 대한 문제점을 연구하는 것이다.

• Nutrition Research and Practice
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• 제2권2호
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• pp.121-129
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• 2008

This study was conducted to develop the NutriSonic Web Expert System for Meal Management and Nutrition Counseling with Analysis of User's Nutritive Changes of selected days and food exchange information with easy data transition. This program manipulates a food, menu and meal and search database that has been developed. Also, the system provides a function to check the user's nutritive change of selected days. Users can select a recommended general and therapeutic menu using this system. NutriSonic can analyze nutrients and e-food exchange ("e" means the food exchange data base calculated by a computer program) in menus and meals. The expert can insert and store a meal database and generate the synthetic information of age, sex and therapeutic purpose of disease. With investigation and analysis of the user's needs, the meal planning program on the internet has been continuously developed. Users are able to follow up their nutritive changes with nutrient information and ratio of 3 major energy nutrients. Also, users can download another data format like Excel files (.xls) for analysis and verify their nutrient time-series analysis. The results of analysis are presented quickly and accurately. Therefore it can be used by not only usual people, but also by dietitians and nutritionists who take charge of making a menu and experts in the field of food and nutrition. It is expected that the NutriSonic Web Expert System can be useful for nutrition education, nutrition counseling and expert meal management.

• International Journal of Industrial Entomology and Biomaterials
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• 제3권1호
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• pp.97-99
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• 2001

Seven vegetables were planted in green houses to compare their yields and damages by insect pests based on three treatments, green music (GM), ultra sonic (US) and control. The vegetable yields of GM treatment were increased by an average of 17.81% than that of control for two years. There was a remarkable statistic difference in the yield between GM and respective controls such as radish, young radish, cucumber, spinach and Brassica oleracea var. acephala. There was no notable yield difference between US and controls for the semen vegetables within two years. The population densities of the insect pests in GM and US treatments were lower than controls. Only a few insect pests of some vegetables in GM and US treatments injured more seriously than in control.

• 한국유체기계학회 논문집
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• 제3권2호
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• pp.44-49
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• 2000

Small sonic nozzles (throat diameter $0.28{\~}4.48mm$) were tested in the gas flow standard system. This standard system is composed of two bell provers and 5 column piston provers, compressor, filters, and dehumidifier. The discharge coefficients of small some nozzles are obtained and correlated as a function of throat Reynolds numbers with $0.316\%$ uncertainty at a confidence level $95\%$. The tested high Reynolds number was the lower limit of ISO 9300 specifications. The data are useful as data base for revision of ISO 9300.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.454-457
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• 2004

AGV for FMS must be detected an obstacle. Therefore, many studies have been advanced, and recently, the ultra sonic sensor is used for this. However, the new method has to be developed because the ultra-sonic-sensor has many problems as a noise in factory, an directional error and detection of the obstacle size. So, we study the fast stereo vision system that can give more information to obstacles for intelligent AGV system. For this, the simulated AGV system was made with two CCD cameras in front to get the stereo images, and the threshold process by color information (intensity and chromaticity) and structure stereo matching method were constructed.

• 한국항해학회지
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• 제3권2호
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• pp.21-30
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• 1979

Echo sounder and Doppler sonar are to theultra-sonic transducers for measuring the depth and the ship's speed respectively. To measure the depth and speed with a single transducer, it is required to control the ultra-sonic beam to optional direction. In the past, the direction of the transducer itself is varied, but such a method provoked much problems in the mechanical design of the equipment. This paper deals with the method to control beam direciton by the phase control of the plural arrangement of transducers, and the results are studied by a computer simulation. The remarkable results of the study is condensed as follows; 1. The greater the interval of arrangement between transducers, the sharper the radiation pattern is, but in this case, the level of undesired sidelobe is also increased. 2. The control of radiation pattern up to 60 degree can be achieved by an adequate arrangement of more than 10 transducers. 3. It is shown that a simultaneous measurement of both depth and speed can be achieved by alternating directivity of the pulse by the method proposed in this paper.

• Journal of Mechanical Science and Technology
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• 제19권9호
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• pp.1706-1710
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• 2005

In a case of computer simulation used for the verification of pneumatic system performance one of the main problems is that various parameters can be used to describe flow characteristics of the system components. The Standard ISO 6358 offers two parameters: the sonic conductance C and the critical static pressure ratio b, but the parameters can not be directly utilised in an analysis of a pneumatic system. In the standard analysis there is applied the airflow coefficient ${\mu}$, but it is not presented in the vendors' catalogues. In the paper the numerical algorithm for calculation of the airflow coefficient ${\mu}$. (which is required for computer simulation) as a function of sonic conductance C and a critical pressure ratio b (recommended by the standard) is presented. Additionally, because of the iterative character of the described algorithm, an artificial neural network approach to solve the problem is proposed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.221-224
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• 2002

A technique of mixing enhancement in an underexpanded sonic round jet is studied with fully expanded jet Mach number 1.5. Tonal sound, jet screech can be produced at some underexpansion pressure ratio in a sonic jet. Since the jet screech excites the initial Jet shear layer to change the flow, a reflector which focuses the jet screech near the nozzle lip is designed. The reflector has an elliptic shape of which two foci are located near the nozzle lip and the jet screech source region. Jet screech tone near the nozzle lip increases with the elliptic reflector and spreading of the jet largely increases. It is concluded that mixing enhancement of the jet with the elliptic reflector is attributed to large scale structures which are initially excited by the increased jet screech.