• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.1377-1380
• /
• 2008

An irradiation test of a nuclear fuel rod having external and internal tube structure was planned for a performance. To establish fabrication process satisfying the requirements of irradiation test, micro-TIG welding system for fuel rods was developed, and preliminary welding experiments for optimizing process conditions of fuel rod was performed. Fuel rods with 15.9mm diameter and 0.57mm wall thickness of cladding tubes and end caps have been used and optimum conditions of endcap welding have been selected. In this experiment, the qualification test was performed by tensile tests, helium leak inspections, and metallography examinations to qualify the endcap welding procedure. The soundness of the welds quality of a dual cooled fuel rods has been confirmed by mechanical tests and microstructural examinations.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집B
• /
• pp.943-948
• /
• 2000

The Twin-fluid Swirl Nozzles are used in many parts of the industry to produce homogeneous spray. This study is to investigate the effects of outer air swiller and inner water swiller on atomization of liquid.. The experiment was carried out with increasing air-flow rate at constant liquid-flow rate and with changing outer air swiller angle and inner water swiller angle. A Particle Dynamics Analyzer(PDA) was used to measure drop size, mean and ms values of axial velocity, number density and Sauter mean diameter(SMD). The axial mean velocity and SMD of droplets were measured along the center line and radial directions. It was found that the higher air flow-rate resulted in the smaller Sauter mean diameter of liquid spray and the higher axial mean velocity of droplets. This experimental results will be conveniently used for the preliminary design stage of twin-fluid nozzle development.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1998년도 추계학술대회
• /
• pp.151-152
• /
• 1998

The sensing of urination level of bladder urine volume is effective for preventing the urinary incontinence which is one of the three major infirmities afflicting the elderly. In this study, we found that it is useful for manufactured ultrasonic urination sensor to measure between distance of anterior and posterior wall of bladder, as a preliminary experiment. Also, Thee was a intimate interrelation between urine volume level and interwall distance of bladder.

• 한국정밀공학회지
• /
• 제13권6호
• /
• pp.128-135
• /
• 1996

This paper proposes a high precision measurement technique to obtain the height of gage block with a few millimeter height. The proposed technique is consisted of two steps : In the first step, laser position transducer and electric micrometer are adopted to obtain a coarse value of the height of gage block, and then, in the second step, heterodyne laser interferometry is adopted to acquire the precision value. A new kind of phase detector is constructed in the low cost for the heterodyne interferometer and its linearity with ${\pm}1%$ is confirmed by experiment. Also measurement error factors due to enviroments are discussed and methodology to reduce such errors is proposed. Preliminary experiments are carried out for the gage blocks of as high as a few millimeter.

• Natural Product Sciences
• /
• 제14권1호
• /
• pp.47-50
• /
• 2008

To evaluate the antiallergic effect of the dried root of Astragalus membranaceus Bunge (AM) (Leguminosae), which inhibited the mouse passive cutaneous anaphylaxis (PCA) reaction in a preliminary experiment, its main constituents, astragalosides I and IV, were isolated and their antiallergic effects were investigated. Astragalosides I and IV inhibited the PCA reaction induced by the IgE-antigen complex, and the scratching behaviors induced by compound 48/80. These constituents reduced the protein expressions of $TNF-{\alpha}$ and IL-4 in IgE-induced RBL-2H3 cells. These findings suggest that astragalosides I and IV as well as AM can improve IgE-induced anaphylaxis and scratching behaviors.

• 한국식품위생안전성학회지
• /
• 제11권1호
• /
• pp.51-55
• /
• 1996

As a preliminary experiment to investigate the effect of ozone sterelization on the ginseng powder, the changes of fatty acid composition and organic acid content and sensory properties in ginseng powder treated with ozone was investigated. Ginseng powder was treated with 0.5 ppm ozone for 24 hours and 48 hours, respectively. With increase in ozone treatment time, the content of crude lipid and increase. Contents of unsaturated fatty acid-linolenic acid, linoleic acid, and oleic acid, etc.-decreased with ozone treatment time, whereas saturated fatty acid or same number-stearic acid-increased odor, bitter taste, roasted taste and sweet taste were thiner with ozone treatment times, but pungent taste was thicker with those treatment. These changes of ordors and tastes of ginseng powder with ozone treatment were predicted by oxydation of lipids, flavor components and saponins.

• Journal of Radiation Protection and Research
• /
• 제38권4호
• /
• pp.185-188
• /
• 2013

Heating method using electric heater was used to reduce water content in fingernail clippings. Authors found that low water content is helpful to measure EPR signal of fingernail sample with enhanced variability. Generally, natural dehydration happens in normal room condition at least one month and needs much time for using in experiment. So, artificial heating method is applied in this study for time savings. Fingernail samples were tested to find effect of water content to the EPR signal on microwave power levels for dosimetry. Low water content in fingernail reduced variability of EPR signal and makes it possible to measure accurate EPR signal. It also made it possible to measure constant movement of EPR signals on several microwave power levels. Although this method was difficult to apply directly in fingernail/EPR dosimetry, we, authors, believe that this heating method would be useful to differentiate MIS2 and RIS which are generally located at the same g-factor and almost impossible to be identified with each other.

• 음성과학
• /
• 제2권
• /
• pp.95-108
• /
• 1997

The purpose of this experimental study was to investigate prosodic characteristics of English as spoken by Koreans. Test materials were four English words, a sentence, and a paragraph. Six female Korean speakers and five native English speakers participated in acoustic and perceptual experiments. Pitch and duration of word syllables were measured from signals and spectrograms made by the Signalize 3.04 software program for Power Mac 7200. In the perceptual experiment, accent position, intonation patterns, rhythm patterns and phrasing were evaluated by the five native English speakers. Preliminary results from this limited study show that prosodic characteristics of Koreans include (1) pitch on the first part of a word and sentence is lower than that of English speakers, but the pitch on the last part is the opposite; (2) word prosody is quite similar to that of an English speaker, but sentence prosody is quite different; (3) the weakest point of sentence prosody spoken by Koreans is in the rhythmic pattern.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 1996년도 제6회 학술강연회논문집
• /
• pp.197-205
• /
• 1996

A combined extrusion process studied here consists of forward and backward extrusion, and it is formed in single operation. The metal flow involved in the operation has appeared to be difficult to analyze accurately because of mixed directions of the flow. In this study, conventional two operations of a forward and a backward extrusions is transformed into one operation of mixed extrusion. A process designed by an industry expert is simulated by the rigid-plastic finite element method to investigate the metal flow and defects. In addition to the FEM simulation, experimental analysis has been carried out to confirm the design in industry, which includes material characterization, preliminary expriment, and whole experimental forming operation. The experimental results show that warm forming of extrusion is more desirable than cold working and hot forming in view of grain growth. Also two conditions of lubrication between workpiece and die has been investigated.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2011년도 정기 학술대회
• /
• pp.673-675
• /
• 2011

본 연구에서는 매립 구간의 길이가 유도초음파 신호 강도에 미치는 영향을 분석하였다. 유도초음파 모드 해석을 통해 가진 모드와 주파수를 결정하였으며, 유도초음파의 가진 및 수진은 경사각 입사 방식의 Pitch-Catch 법을 이용하였다. 또한, 비 매립된 배관에서 유도초음파 신호를 획득하여, 이를 기준으로 매립된 배관에서 획득한 유도초음파 신호를 분석하였다. 실험 결과 매립 구간의 길이가 유도초음파의 신호 강도에 매우 큰 영향을 미칠 뿐만 아니라, 매립 구간의 길이와 신호 강도의 변화가 선형 비례적인 관계를 보이지 않는다는 것을 확인할 수 있었다.