The research vessel NARA equipped with an azimuth thruster system was built in 2015. There are few vessels with this propulsion system in Korea. This vessel has two modes such as the normal for maneuvering and the power for investigation, and the other two modes as one axis and two axes on the operating. This type of vessels does not seem to have a clear grasp of the maneuvering character in comparison with the vessel with a conventional propulsion system. So the authors carried out the sea test for the turning, the zigzag and the inclination, and the results are as follows. In turning test, the case of using the two axes mode is much better than the case of using the one axis mode for the elements of turning, such as advance, transfer, tactical diameter and final diameter, but turning hard over the rudder in full speed is very vulnerable to capsize in both modes. In zigzag test, the yaw quicking responsibility index,  is very large excessively, which means a bad counter maneuvering ability, so an operator has to keep in mind that in turning operation. If necessary to avoid collision at head on situation, it may be a more effective method to use the crash astern stop than the turning according to the conditions and circumstances for the shortest stopping distance is very short.

This study was performed to analyze the psychologic change of Tae-kwon-do Athletes who were wearing the mouth guard and one of contact sports during their matches of Tae-kwon-do 10 selected Tae-kwon-do athletes who had no injuries which they had college Tae-kwon-do sparring matches in the Cheon-an area have participated in the study. The oral impressions if the selected athletes were taken to produce for individual custom mouth guards. After the mouth guards were produced, each of them sat in a chair and attached G.S.R. surface electrodes in the palms of the ends of the second and third fingers of their left hands without moving their left hands, And then they were asked to watch footages of Tae-kwon-do games to stimulate them as if the had have a mock match, and Labscribe2 which are one of polygraphy was used to record their G.S.R. values. To determine whether the mouth guards affected the changes of their psychological status during the sparring matches of not, the experimental group wore the mouth guards while they watched the footages, and the control group didn’t wear any mouth guards. The G.S.R. values of the two groups were measured while the watched the footages. To see if there were and significant polygraphy differences between the experimental group and the control group in G.S.R. values, a statistical package SPSS was used to make a comparative analysis. And there were significant change in between the experimental and control group that wore the mouth guards, and it was concluded the wearing mouth guards exerts an influence on change in the psychological state of Tae-kwon-do athletes while they watch a footage of mock match.

In this study, the boundary non-linear analysis of the sky bridge subjected to walking load and running load is performed. The sky bridge is installed in the mid-story between two buildings and the walking load and running load induced by pedestrians are measured by load cell. LRB is modeled as a non-linear hysteresis model to accurately represent the behavior of LRB. For the serviceability evaluation of sky bridge, the acceleration responses of sky bridge are analyzed based on ISO 2631-2 and the velocity response are analyzed based on standards Bachmann &Amann. In serviceability evaluation of this sky bridge, the pedestrian can not perceive the vibration except for resonance running loads consequently. Therefore, it is concluded that this sky bridge haven’t problem in the serviceability.

A press which has a 20 percent share in machine tools is one of the production facilities. Recently hydraulic press is used to reinforce competitiveness of the manufacturing industry. The press by using metal powder makes products without additional process while conventional processing machine makes products after removing unnecessary parts. In this way, large quantity of products can be produced in a short time. Researches to manufacture products by the press have been proceeding after 1970. In this study, structure and displacement analysis for shape parameters for punch used as the component for hydraulic press was investigated and structural stability was identified based on the results.

분리막 오염을 감소시키고 투과유속 향상을 위하여 관형분리막 모듈 내에 공기 분사노즐관을 삽입시켰다. 분리막 의 평균 기공크기는 0.1 μm이며 이스트를 오염물질로 사용하였다. 모든 투과실험은 노즐관을 모듈에 장착하고 공기를 주입 하지 않는 실험을 먼저 실시하고 연속해서 공기를 주입하는 투과실험을 하였다. 그 다음 노즐관을 제거한 후 공기를 주입시 키지 않으면서 투과유속을 측정하였다. 측정된 투과유속은 공기주입 효과를 분석하기 위하여 비교하였다. 공기주입에 대한 투과유속은 거의 일정하거나 증가하였다. 노즐관이 장착되고 공기 주입을 하지 않을 경우의 투과유속이 빈 관형 모듈의 경우 보다 높았다. 운전압력을 0.4 bar까지 감소시키면 노즐관이 장착되지 않는 경우와 비교하여 공기를 주입할 경우 투과유속이 21%까지 향상되었다. 기체량이 증가하여 기/액체 2상 흐름이 stratified-smooth에서 intermittent 상태로 변화됨에 따라서 공기 주입에 의한 투과유속은 30% 이상으로 증가하였다

본 연구는 불쾌감을 유발하는 구취의 자가 인지도와 의치장착의 관계를 알아보고, 일반적 특성에 따른 구강보건지수 와 의치관련 요소가 구취에 미치는 영향을 설문 및 구강검사를 통해 확인하였다. 경로당 및 노인복지관을 방문한 노인 103명을 분석한 결과 평균 연령은 75.06세 이며, 대상자들 중 의치장착 여부에서 ‘장착한 사람’이 55명(53.4%), ‘장착하지 않은 사람’이 48명(46.6%)으로 나타났다. 일반적 특성에 따른 구강보건지수를 살펴본 결과 성별에 따른 구강건강 상태의 차이는 없었지만 연령이 낮을수록 구강건강 상태가 양호한 것으로 나타났다. 또한 ‘배우자’와 함께 거주 할수록 구강상태는 좋은 것으로 나타났으며, 칫솔질 횟수가 적을수록 구강상태는 좋지 않았다. 의치 사용 유무에서 의치를 사용하는 그룹에서 유의미하게 구취발생률이 높았고, 의치에 대한 구강지식이 높을수록 자가인지 구취의 수준 은 높았으나 구강검진을 통한 구취의 실제 발생량은 낮았다. 의치의 종류에 따른 구취발생 정도 또한 유의미하게 차이를 보였다. 즉, 구취의 발생요인을 단정하거나 단편적으로 해석하기는 어려우나, 노인을 대상으로 불쾌감을 유발하 고 대인기피증과 같은 노인성 문제를 야기할 수 있는 구취의 조절과 의치관리를 위한 구강보건 교육프로그램의 개발이 필요할 것으로 사료된다.

A press which has a 20 percent share in machine tools is one of the production facilities. The press has been used to make a hole or to bend metal plates. However, recently hydraulic press is used to reinforce competitiveness of the manufacturing industry. The press by using metal powder makes products without additional process while conventional processing machine makes products after removing unnecessary parts. In this way, large quantity of products can be produced in a short time. Researches to manufacture products by the press have been proceeding after 1970. In this study, structure and displacement analysis for punch used as the component for hydraulic press was investigated and structural stability was identified based on the results

It is necessary to make preventive method for the trauma and disturbance complications of orofacial area because athletic trauma are physical and mental defects. Since 1913, an italian boxer discussed mouth guard with dentist and used it. It was reported that mouth guard from field prevented trauma, increased the muscle force and activated electromyogram although the history of mouth guard wearing was short. The mouth guard has prevented the trauma and also increased the muscle force. The purpose was to study muscle force and activity of EMG with mouth guard wearing. It concluded that mouth could prevent trauma and increase the muscle force

본 연구에서는 양이온 교환막으로 Sulfonated poly(ether ether ketone) (SPEEK)를 사용하였고, 음이온 교환막은 poly(vinyl alcohol) (PVA)과 poly(vinyl amine) (PVAm)을 혼합하여 가교시킨 막을 이용하였으며, 이에 대한 막결합형 축전식 탈염 공정(Membrane capacitive deionization, MCDI)의 성능실험을 진행하였다. 음이온 교환막의 함수율, 이온교환용량, FT-IR 측정을 통하여 막의 특성을 알아보았다. 음이온 교환막의 가교 시간이 3 h에서 5 h으로 증가할수록 염 제거 효율은 81.3%에서 65.7, 53.8%로 감소하였다. PVAm의 농도를 40, 60, 80%로 달리하여 실험한 결과 염 제거 효율은 81.3, 75.2, 37.7%로 PVAm이 80% 함량일 때 가장 효율이 떨어졌다. 이는 음이온 교환막의 가교 시간과 PVAm의 농도가 염제거 성능에 영향을 미치는 것으로 사료된다.

Diesel engines show better thermal efficiency and fuel consumption, but diesel engines typically generate more NOx emissions because of lean-burn conditions. Therefore, it is necessary to reduce the emissions of diesel engines either by efficiently controlling combustion or by employing exhaust gas after-treatment systems. In this study several problems we're observed in a SCR system and Engine control system. The analysis result, new technology SCR is suitable for the vehicle with low temperature operating condition. Through this analysis we can find out more effective repair factors from the various fault in SCR component.

Emission regulation by Europe and the U.S. on air pollutants from diesel automobiles which include particulate matter and nitrogen oxides are becoming stricter than ever. The SCR uses Urea, which is NH3 diluted by water, and chemically reacts with emission gases reducing over 90% of the NOx created. In this study several problems were observed in a SCR system and Engine control system. Through this analysis we can find out more effective repair factors from the various fault in SCR component.

In this study, temperature variation characteristics in a flat plate with sheath heater are investigated through experiment and numerical analysis. ANSYS fluent is used to calculate the temperature distribution in the heating plate system. Transient condition is applied to observe temperature variation with the sheath heater operation, and thermal resistance on the contacted surfaces is also considered. Experimental data agree well with numerical results obtained for heat generation rate from sheath heater, Local temperature variation on the surface of flat plate is also predicted through this simulation. There is large temperature variation in the air surrounded flat plate, especially at the top of flat plate with natural convective heat transfer. These results will be helpful in optimal design for various systems equipped with sheath heater.

이온교환막이 결합된 축전식 탈염공정(Membrane capacitive deionization, MCDI)을 진행하기 위하여 양이온고분자로는 Sulfonated PPO(Poly(2,6-dimethyl-1.4-phenyl oxide)를 사용하였으며 음이온고분자로써 Aminated Polysulfone을 제조하여 전극 표면에 직접 코팅하여 사용하였다. 코팅여부는 SEM 사진을 통하여 확인하였으며, 성능을 알아보기 위하여 흡/탈착실험을 진행하였다. 유속(15, 25, 30 ml./min), 흡착시간(2, 3, 5, 7 min), 유입수의 농도(100, 200, 300, 500ppm)를 변화시켰는데 그 결과 유속은 느릴수록, 흡착시간은 길어질수록, 유입수의 농도가 낮을수록 염 제거 효율이 높게 나타났다.

In military, Electro-optic/Infra-red system that is used to obtain the target image of high performance induced blur images by the vibration of the carrier and inner optical devices. Optical devices of the EO/IR is constituted by the optical lens, detector and mechanical assembly. High performance detectors for IR camera are typically used for stirling cryocooler to maintain the temperature of the detection surface cryogenically. However, This cooler induces a blur image on detector surface by the vibration. In this study, we performed modal analysis and response analysis of the mounting structure design which can minimize the vibration of the cooler and detector. Also, We confirmed that we were designed robust mounting structure according to the vibration through the response analysis models the inner gimbal and optics.

Increasing specific power, torque and high responsibility have come to the fore as the important strategy of reducing fuel consumption in vehicle engines. Therefore, the boosting performance of various boosting devices has been investigated using a diesel engine simulation program. For the comparison of boosting performance, the simulation result of a naturally aspirated 2.0 liter engine is used as a basis. Subsequently, the boosting effects of single turbocharger, single supercharger and 2-stage boosting system combined with a turbocharger and a supercharger are compared at the same engine condition. The simulation results show that the 2-stage boosting system can attain lower specific fuel consumption and higher air mass flow. In low engine speed range, a supercharger mainly leads higher boosting performance with higher responsibility in the combined boosting system.

LED는 전기에너지를 빛에너지로 전환하는 효율이 높기 때문에 차세대 광원으로 주목되고 있다. 그러나 조명성능을 향상시키기 위해서는 접합부에서 발생된 열을 적절히 방출하여야 하며, 밀폐형의 경우 방열판으로 전달되는 열을 외부로 배출하는 최적의 설계가 필요하다. 이 연구에서는 LED 조명의 캐비넷 냉각시스템에 설치되는 냉각팬의 위치를 수치해석의 방법으로 고찰한 결과 y/H=0.8 근방이 최적의 위치였다.

콴다 효과를 이용한 고 양력 타가 선박의 조종성능에 미치는 영향을 평가하기 위하여 모형선 선회 시험을 수행하였다. 대상선은 47K PC선이며 1/85 스케일의 2m급 모형선을 이용하였다. 모형선 선회시험시스템은 모형선, 콴다 타, Jet 분사 시스템 및 타 구동장치 등으로 구성된 다. 모형선 선회 시험 결과, 고 양력타에 의한 타력 증가가 선박의 선회성능 향상에 효과적인 것을 확인하였다.