• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.127-132
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• 1975

This is an experimental study that aimed to find out a possible relationships between the noise of the ship and the intelligent quotient, and the creativity of the crew member during June 5, to August 24, 1975. The experiment was carried out on the university training ship, the Oh-Bae-San Ho(1,126 tons), and the Kwan-Ak-San Ho (243 tons) and the training ship Baek-Kyung Ho (380 tons) of Je-ju College, where the total number of 144 students engaged on their tasks of practical exercise. And the following results were obtained : The decreases of I.Q. was evident as compared to the score obtained at the class room; soon after the embarking of the ship, the students on the deck decreased the score by $7\%$ of what they obtained at the class room while the students in the engine room decreased by $13\%$. The I.Q. was regaining the normal state after three days of embarking seemingly showing the fact that the students became adapted to the noise of the ship, but no remarkable improvement was visible during the period of 3 days to 35 days on the ship. One of the remarkable fact that had not been expected was that the problems for audio discernment was much easily solved in the midst of noise that made oral communication impossible (102 dB) than in the place of noise where conversation was possible(67 dB).

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.1
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• pp.20-25
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• 2013

Ultrasonic methods are widely used to degradation assessment. Remaining-life cycle of metal can be estimated by ultrasonic parameters because ultrasonic velocity and attenuation are affected by change of material properties with accumulated fatigue in the metal. Therefore, in this study, we will estimate overall change of material properties by 2D C-scan image. Fatigued aluminum alloy 6061-T6 samples from 0 to 85% were prepared for evaluating fatigue life cycle. Also, degraded image of materials using attenuation is proposed to estimate degree of material degradation for determining degraded area of fatigued samples. Finally, we will predicts process pf degradation with measured attenuation of fatigued aluminum alloy 6061-T6 samples.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.466-473
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• 2016

In a shipbuilding process, thermal damage to the ship structure at the rear end results from an excessive heat input and conduction during welding process. To prevent such damage, appropriate control of the heat input, based on welding temperature measurement, is required. For temperature measurement, contact and non-contact methods are available; the thermography system is a popular non-contact temperature measurement. When the intensity of radiation from a high-temperature object is excessive, however, detecting the sensors of ordinary thermography systems leads to an inability in measuring the temperature due to saturation. Hence, this study suggests use of a neutral density filter that prevents an excessive amount of radiation from being accumulated in a thermography system, and thus makes it possible to quantitatively measure an object's temperature as high as $3000^{\circ}C$.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.49-59
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• 1984

Optimizing investigation of characteristics of underwater welding by a gravity type arc welding process was experimentally carried out by using six types of domestic coated welding electrodes for welding of domestic marine structural steel plates (KR Grade A-1, SWS41A, SWS41B,) in order to develop the underwater welding techniques in practical use. Main results obtained are summarized as follows: 1. The absorption speed of the coating of domestic coated lime titania type welding-electrode became constant at about 60 minutes in water and it was about 0.18%/min during initial 8 minutes of absorption time. 2. Thus, the immediate welding electrode could be used in underwater welding for such a short time in comparison with the joint strength of in-atmosphere-and on-water-welding by dry-, wet-or immediate-welding-electrode. 3. By bead appearance and X-ray inspection, ilmenite, limetitania and high titanium oxide types of electrodes were found better for underwater-welding of 10 mm KR Grade A-1 steel plates, while proper welding angle, current and electrode diameter were 6$0^{\circ}C$, above 160A and 4mm respectively under 28cm/min of welding speed. 4. The weld metal tensile strength or proof stress of underwater-welded-joints has a quadratic relationship with the heat input, and the optimal heat input zone is about 13 to 15KJ/cm for 10mm SWS41A steel plates, resulting from consideration upon both joint efficiency of above-100% and recovery of impact strength and strain. Meanwhile, the optimal heat input zone resulting from tension-tension fatigue limit above the base metal's of SWS41A plates is 16 to 19KJ/cm. Reliability of all the empirical equations reveals 95% confidence level. 6. The microstructure of the underwater welds of SES41A welded in such a zone has no weld defects such as hydrogen brittleness with supreme high hardness, since the HAZ-bond boundary area adjacent to both surface and base metal has only Hv400 max with the microstructure of fine martensite, bainite, pearlite and small amount of ferrite.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.104-111
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• 2009

A ship engine operator should compensate the crankshaft assembly of ship engine after inspecting crankshaft deflection error in the crank throw regularly to avoid engine vibration and abrasions. In the previous method, the operator enters the bed plate and measures crankshaft deflection using dial gauge on rotating crankshaft manually. However, this method can cause dangerous situation to the operator as well as uncomfortable in an inferior environment. In order to solve the problems, this paper studies the method which makes the operator measure the error outside of the bed plate. In this paper, it is suggested that BlueTooth wireless communication transfers the error data to the outer standing operator with digitalized crankshaft deflection inspection device developed in this paper. So, the wireless measurement system is developed and applied to a medium-speed marine engine through size-miniaturization. After applying test, the developed inspection device showed that it provides much safe and ease inspection method. Furthermore, in the result, the measuring accuracy is more improved.

• 월간 기계설비
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• no.12 s.209
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• pp.34-43
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• 2007

환경부는 산하 수처리선진화사업단에서 수돗물 수질개선대책의 일환으로 연구개발한 옥내급수관 진단, 세척 및 갱생기술을 적용, 서울시와 공동으로 시범사업을 실시한다고 밝혔다. 이 사업은 서울 둔촌동 주공아파트 2개동 80세대를 대상으로 약 1억2000만원의 예산을 들여 지난 8월 말부터 시행, 수돗물 녹물발생 방지를 위한 갱생기술의 완성도를 검증·확인한다는 것. 기존 옥내급수관 갱생기술은 평균 관직경 15mm인 소형관에 대한 정밀시공이 어려워 녹이 재발하는 경우가 많았다. 하지만 이번에 개발된 기술은 수도관 내부의 녹 제거 및 관 내부 표면이 균일토록 코팅할 뿐 아니라 시공 후 마이크로 로봇을 이용, 관 내부 촬영 및 절연도 체크를 통해 코팅 완성도를 확인, 녹 재발 가능성을 미연에 방지한다. 이번 기술이 검증되면 환경부는 선박배관, 빌딩, 냉각수배관, 소화용배관, 산업용배관 등에도 확대 적용하고 해외진출을 통해 물산업 육성 아이템으로 발전시킬 계획이다. 한편 환경부는 지난 2005년 수도법을 개정, 건축연면적 6만$m^2$이상 다중이용건축물과 연면적5,000$m^2$이상 국.공립 공공시설은 준공 5년 후부터 매년 수질검사를 실시, 결과에 따라 수도관을 세척·갱생 또는 교체토록 올해 1월부터 의무화 하고 있다.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.74-83
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• 2001

After the concept of fracture mechanics was applied to fatigue crack propagation by Paris. Paris' law is widely used to predict fatigue crack growth behavior. Since Elber proposed the effective stress intensity factor(SIF) and showed a good agreement with experimental results using the proposed SIF, emphasis in crack propagation studies has been placed on measuring the effective stress range ratio. This paper proposes a numerical model to simulate the crack closure and propagation behaviour under various loading spectrum. The validity of the proposed model is checked by comparing with the Toyosada numerical solutions on the crack propagation behaviour. Important insights developed are summarized.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.155-164
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• 2014

Carbon-fiber-reinforced plastic (CFRP) composites are increasingly being used in a variety of industry applications, such as aircraft, automobiles, and ships because of their high specific stiffness and high specific strength. Aircraft are exposed to high temperatures and high humidity for a long duration during flights. CFRP materials of the aircraft can absorb water, which could decrease the adhesion strength of these materials and cause their volumes to change with variation in internal stress. Therefore, it is necessary to estimate the characteristics of CFRP composites under actual conditions from the viewpoint of aircraft safety. In this study air-coupled ultrasonic testing (ACUT) was applied to the evaluation of water absorption properties of CFRP composites. CFRP specimens were fabricated and immersed in distilled water at $75^{\circ}C$ for 30, 60, and 120 days, after which their ultrasonic images were obtained by ACUT. The water absorption properties were determined by quantitatively analyzing the changes in ultrasonic signals. Further, shear strength was applied to the specimens to verify the changes in their mechanical properties for water absorption.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.525-534
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• 2018

This study evaluated the various qualifications that can be linked to employment similar to the medical laboratory technology major. The qualifications for employment outside the medical laboratory technology major are industrial health instructor, doping control officer, audiologist, sign language interpreter, health education specialist, claim adjuster, Korea life underwriter, administrative manager, hospital administrator, insurance review manager, and hospital coordinator. The qualifications for employment similar to the medical laboratory technology major include the clinical research coordinator, clinical research associate, anatomist, analytical chemistry analysts, hazardous materials industry engineers, biotechnologist, biosafety managers, biotechnology technicians, medical device quality officers, animal care nurse, industrial engineer hazardous material, bioprocess engineer, biosafety officer, certified technology consultant, director of medical device quality control, laboratory animal technician, animal nursing technician, and cruise medical manager. Therefore, it is necessary to conduct a social analysis survey of the various qualifications currently held by medical technologists. In addition, it will be necessary to investigate the current status of medical technologists working in other fields. In the future, medical technologists should expand the scope of their work through efforts to strengthen their individual work capacity, share cases, and strengthen their expertise.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.1
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• pp.21-29
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• 1993

The magnetic compass as a principal navigational instrument has been long used to fix ship's position and to determine ship's course. Particularly, in the small fishing vessels the studies on performance and rational usages for magnetic compass are requried to improve the safety and productivity of the small fishing vessels even though gyro compass is developed nowadays. For this purpose, the author examined the present condition of the magnetic compasses which are intalled on 219 small fishing vessels, and carried out a series of performance survey for each compass of them and also found the measured values of deviation by installation position of compass, respectively. The results obtained are summarized as follows: 1. The small fishing vessels less than 4 tons among the 219 small fishing vessels from 1 to 10 tons investigated were 50% of them. Only 1% of them were equipped with the deviation correctors, and 14 fishing vessels used the magnetic compasses which are more than 20 years old. 2. According to the compass installation position, the measured values of the deviation of the compass installed on the top bridge and the compass bed in bridge were ascertained to be the smallest, and those values of the compass installed on the bridge deck above engine room were larger and irregular. 3. The concomitant angle of the magnetic compasses installed on the experimented 4 fishing vessels were measured to be 6$^{\circ}$ to 16$^{\circ}$ and not accorded with the Korean standard values.