• Parasites, Hosts and Diseases
• /
• 제23권2호
• /
• pp.305-312
• /
• 1985

Ixodes persulcatus 진드기의 표면구조 관찰을 위하여 교미중에 있는 자웅 성충 표본을 주사전자현미경으로 사진을 촬영하여 영상을 분석하였으며 아울러 생태와 질병과의 관련성에 대하여 문헌고찰을 하였던 바, 다음과 같은 결과를 얻었다. 1. 자웅표본간에 성별에 따른 외형상의 차이가 명백하였으며 자충은 웅충에 비하여 대형의 모습을 나타냈다. 2. 생식구는 깊게 잘 발달되어 있으며, 항문구는 항문주변의 전방으로 명확하고 특징적인 구조를 나타냈다. 3. 제4촉지는 단축되어 있는 형태를 나타내며, 제3촉지의 복방상부에 얹혀져 있었다. 치열에 대한 치식은 일반적으로 3/3을 나타냈다. 4. 웅충에 있어서의 악체부의 배면후방바닥은 반듯한 직선장을 나타냈다. 5. 각종 전염병과 철새와의 관련성에 있어서 동 진드기유는 매개체로서 작용하며 역학상 중요성이 있는 것으로 고찰되었다.

• 센서학회지
• /
• 제14권6호
• /
• pp.374-380
• /
• 2005

Vibration sensors have a wide scope of applications in the field of monitoring systems that needs to perceive an undesirable physical vibration before a critical failure occurs in a system, and then costly unplanned repairs can be avoided. The conventional vibration sensors developed so far have many disadvantages, such as complex manufacturing process, bulkiness, high cost, less reliability and so on. This paper reports a simple-structured vibration sensor, which has been developed using a commercialized conductive ball and silicon bulk-micromachining technology. The sensor consists of a conductive ball placed in $600{\mu}m$-deep micromachined silicon groove, in which Au thin film has been patterned using a shadow mask technique. Prior to the formation of the Au thin film, the sharp convex corner was rounded for smooth meatl deposition on the non-planar surface at the edge of the groove. The measurement results of the fabricated vibration sensor demonstrate a stable response characteristic to low-frequency vibration range ($1{\sim}30{\;}Hz$).

• Journal of Advanced Marine Engineering and Technology
• /
• 제37권6호
• /
• pp.589-595
• /
• 2013

본 논문은 플라즈마 절단 면 특성이 I Groove 서브머지드 아크 용접 용락 현상에 미치는 영향과 용락 현상을 감소시키는 방법에 대하여 연구하였다. 조선해양 구조물의 주판은 대부분 후판으로 설계되고 깊은 용입을 얻기 위하여 고 전류를 사용하게 된다. 용접부의 절단 품질에 따라서 서브머지드 아크용접 진행 시 용락 현상이 자주 발생되고 이는 용접부의 품질 저하와 수정 작업을 유발시킨다. 본 연구의 플라즈마 절단 실험에서 나타난 특성으로 I형상 그루브 직각 절단 시 상,하면에 플라즈마 열원에 의한 녹음 현상과 함께 하면 한 방향에 약 2~4도 정도의 각 변형 베벨이 형성됨을 확인하였다. 이는 맞대기 이음에서 용락 현상의 주된 원인이며 모재 절단 시 상면 방향에 I 그루브 형상에 가깝도록 한 방향 기준으로 V형상 그루브 4도 베벨을 시공하여 서브머지드 아크 용접을 실시한 결과 용락 현상을 현저히 저감시키는 결과를 얻을 수 있었다.

• 대한기계학회논문집A
• /
• 제30권2호
• /
• pp.157-163
• /
• 2006

Our research dealt with micro fabrication using micro forming process. The goal of the research was to establish the limit of forming process concerning the size of forming material and formed shape. Flat-rolled ultra thin metallic foils of pure copper(3.0 and $1.0{\mu}m$ in thickness)and stainless steel($2.5{\mu}m$ in thickness) were used for forming material. We obtained the various shapes of micro channels as using designed forming process. $12-14{\mu}m$ wide and $9{\mu}m$ deep channels were made on $3.0{\mu}m$ thick foil and $6{\mu}m$ wide and $3{\mu}m$deep channels were made on $1.0{\mu}m$ thick foil. Si wafer die for forming was fabricated by using etching technique. And the relation of etching time and die dimension was investigated for fabricating precisely die groove. For the forming, die and metal foil were vacuum packed and the forming was conducted with a cold isostatic press. The formed channels were examined in terms of their dimension, surface qualities and potential for defects. Base on the examinations, formability of ultra thin metallic foil was also discussed. Finally, we compared the forming result with simulation. The result of research showed that metal forming technology is promising to produce micro parts.

• Tribology and Lubricants
• /
• 제18권4호
• /
• pp.273-278
• /
• 2002

Grease deterioration of mineral oil type grease was investigated using sealed deep groove ball bearings (6203) and bearing life test rig. The bearing test was performed under 3,000 rpm and 245 N radial load at 120。C. Grease taken ken tested bearings was checked in using certain evaluation methods, for example, oxidation induction time (OIT), FT-IR peak intensity, leakage .ate, bleeding .ate, total acid number. (TAN) and bearing noise increase. Within these test conditions, OIT, TAN, bleeding rate were changed gradually in accordance with bearing operating time and showed useful indices for deterioration of grease.

• Tribology and Lubricants
• /
• 제13권4호
• /
• pp.26-32
• /
• 1997

The heat generation of the angular contact and the deep groove ball bearing is studied experimentally and numerically. The temperature variation of the inner and outer races and the temperature increase distribution are measured for the shaft rotational speeds, preloads, viscosities of the lubricant and lubrication methods. The measured temperature distributions are used as the input data of the numerical simulation to estimate the heat generation rate at the bearing. The temperatures of the inner and outer race increase more rapidly and approach faster to their steady values as the rotational speed increases. The optimal viscosity of the oil to minimize the heat generation is 8~10 cSt at 4$0^{\circ}C$ when the oil-air lubrication method is adopted. The heat generation of the bearing increases with the rotational speed and depends more on the lubrication method than on the preload variation.

• Parasites, Hosts and Diseases
• /
• 제52권6호
• /
• pp.685-690
• /
• 2014

A perianal tick and the surrounding skin were surgically excised from a 73-year-old man residing in a southwestern costal area of the Korean Peninsula. Microscopically a deep penetrating lesion was formed beneath the attachment site. Dense and mixed inflammatory cell infiltrations occurred in the dermis and subcutaneous tissues around the feeding lesion. Amorphous eosinophilic cement was abundant in the center of the lesion. The tick had Y-shaped anal groove, long mouthparts, ornate scutum, comma-shaped spiracular plate, distinct eyes, and fastoons. It was morphologically identified as a fully engorged female Amblyomma testudinarium. This is the third human case of Amblyomma tick infection in Korea.

• 항공우주시스템공학회지
• /
• 제10권1호
• /
• pp.35-42
• /
• 2016

Bearing friction and disturbance are the important parameters in control spacecraft using reaction wheel. In this paper, those parameters are estimated by preload and oil quantity. In order to determine the bearing preload's impact on performance, measure the disturbance and the bearing friction coefficient with increasing the preload to the allowed amount. And, find the relationship between oil quantity and bearing friction coefficient, measure it with increasing the oil amount in the bearing. With these results as a reference, find the appropriate amount of preload and oil quantity.

• Tribology and Lubricants
• /
• 제29권4호
• /
• pp.248-254
• /
• 2013

This paper presents a numerical model for investigating the structural dynamic response of an unbalanced rotor system supported on deep groove ball bearings. The aim of this work is to develop a numerical model for investigating the effect of the number of balls on the dynamic characteristics of the rotor ball bearing system. The fourth-order Runge-Kutta numerical integration technique has been applied. The results are presented in the form of time displacement responses and frequency spectra. The analysis demonstrates that the model can be used as a tool for predicting the nonlinear dynamic behavior of the rotor ball bearing system under different operating conditions. Moreover, the study may contribute to a further understanding of the nonlinear dynamics of rotor bearing systems.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
• /
• pp.47-50
• /
• 1987

There are various holographic recording materials, such as Dichromated Gelatin, Silver Halide, Thermoplastic, Photoresist. In this paper especially, we used Photoresist to make the phase holographic grating. Deep-groove diffractive grating formed in relatively thin holographic recording material is to express high diffraction efficiency. Phase holographic grating recorded In photoresist can be used very practical because it has the high diffraction efficiency, and it is possible to make a replication easily. So, it has the merit in recording the optical holographic grating than any other materials.