• 한국가축번식학회지
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• 제16권1호
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• pp.39-46
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• 1992

In viro fertilizatin is very important in both human clinical practice and animal breeding. However, the success rate of in vitro fertilization is not high. The purpose of this study ws to determine wheter in the vitro fertilization and culture of porcine oocyte using a hydrogel chamber were possible or not. Hydrogel chambers were made of polymerized 2-hydroxyethyl methacrylate. Matured follicular oocytes in Waymouth's medium and T L Hepes medium, tubal oocytes, and preincubated sperm in M199 medium were treansferred into the lumen of the hydrogel chambers. The chambers containing porcine oocytes and spermatozoa implanted into the mouse peritioneal cavity, and ova were examined after the recovery of the chambers at 84 hours after preservation start. The result was shown that fertilization and culture of porcine oocytes were successfully achieved inside of the hydrogel chamber.

• 한국해양공학회지
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• 제36권1호
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• pp.21-31
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• 2022

In recent years, various studies have been conducted on oscillating-water-column-type wave energy converters (OWC-WECs) with multiple chambers with the objective of efficiently utilizing the limited space of offshore/onshore structures. In this study, a numerical investigation based on a numerical wave tank was conducted on single, dual, and triple OWC chambers to examine the hydrodynamic performances and the energy conversion characteristics of the multiple water columns. The boundary value problem with the Laplace equation was solved by using a numerical wave tank based on a finite element method. The validity of the current numerical method was confirmed by comparing it with the measured data in the previous experimental research. We undertook a series of numerical simulations and observed that the water column motion of sloshing mode in a single chamber can be changed into the piston motion of different phases in multiple OWC chambers. Therefore, the piston motion in the multiple chambers can generate considerable airflow at a specific resonant frequency. In addition, the division of the OWC chamber results in a reduction of the time-dependent variability of the final output power from the device. As a result, the application of the multiple chambers leads to an increase of the energy conversion performance as well as a decrease of the variability of the wave energy converter.

• 한국수정란이식학회지
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• 제4권1호
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• pp.21-27
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• 1989

Hydrogel chambers made from polymerized 2-hydroxyethyl methacrylate were used for in chamber fertilization. To determine whether sperm motility was preserved in the Hydrogel chamber, chambers which have rabbit sperm or frozen-thawed bovine sperm were transplanted inside of mouse peritoneal cavity and sperm were observed after recovering the chambers in the due time. As a result, it was determined that preservation of sperm motility was good. To determine whether in chamber fertilization was possible, chambers which have rabbit oocytes and sperm were transplanted inside of mouse peritoneal cavity and eggs were observed after recovering the chambers at 84 hr of preservation. As a result, the fact that fertilization and culture was occurred inside of the chamber was determined.

• 한국유체기계학회 논문집
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• 제17권2호
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• pp.41-47
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• 2014

Experimental results are given for the vertical motion of water in the water chambers for wave energy converter aligned along the wave propagation direction in order to avoid the impulsive wave forces. This paper mainly focuses on the property of the amplitude of the vertical motion of the water surface in the chambers. The amplification has been investigated by dimensionless parameters of wave period to resonance period ratio of the U-shaped oscillation, $T/T_r$, chamber size to wave length ratio, l/L, water depth to wave length ratio, h/L, amplitude of up-down motion of water particles to draft of the front wall ratio, ${\zeta}/D$. It has been shown that l/L should be less than 0.1 and as $T/T_r$ approaches unity the up-down of the water in the chambers is amplified. Also, the structure of the walls which form th water chambers has been examined roughly. It is deduced that the chambers set on both sides of the hull of a single-point moored floating vessel is preferable to those set along a fixed structure such as breakwaters.

• 아태비즈니스연구
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• 제2권1호
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• pp.1-22
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• 2011

Chamber of commerce and industry plays important role for development of business community and creating vibrant competition. Present paper compares chambers operations in Bangladesh, especially, Sylhet Chamber of Commerce and Industry(SCCI) by reviewing global models of chambers practices. The study identifies important gaps between international standards and Bangladesh practices. Mostly practiced chambers model in the world are: Continental Model, Anglo-Saxon Model and Mixed model or Asian model. Like other Asian countries, chambers in Bangladesh including SCCI, have been following Mixed Model. The empirical study found that SCCI is performing different developmental functions like accumulating members, collecting revenue, fulfilling corporate social responsibility and providing business development services to its members and business community. The notable constraining factors of SCCI operations are: short term orientation in assembling members, limited functional activities, lack of creative endeavors in diversifying services, linkage between SCCI and academic institutions, poor research involvement etc. The necessary suggestions for improvement of chambers performance include adoption of creative measures in various operations, providing training to the members, assisting entrepreneurs in obtaining industrial finance and extending support in the establishment of specialized industrial zone for attaining long term developmental objectives.

• 설비공학논문집
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• 제8권1호
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• pp.37-44
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• 1996

Water hammer pressure waves were measured in a simplified water piping system with and without arresters and air chambers by the operations of the solenoid valve. Experiments were performed to investigate the effects of the location of the arresters and the effects of the volume of the air chambers on maximum and minimum water hammer pressures and wave frequency for various flow rates.

• 한국식품위생안전성학회지
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• 제38권1호
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• pp.26-30
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• 2023

본 연구에서는 자외선 살균기의 미생물 오염 상태를 분석하고 위생관리 방안을 제시하고자 하였다. 본 실험에 사용된 자외선 살균기는 전라남도 소재 일부 보육시설 98곳의 자외선 살균기를 대상으로 하였다. 일반세균 및 대장균군은 식품공전 미생물 시험법에 따라 실험하였다. 일반 세균은 98개 보육시설 중 67개소(68.4%), 대장균군은 5개 소(5.1%)에서 검출되었다. 식중독세균 실험 결과 Salmonella spp. 등 6종의 식중독세균은 검출되지 않았지만 B. cereus 는 98개 보육시설 중 1개소(2.8%)에서 검출되었다. 자외선 램프 교체 주기에 따른 일반세균 검출율은 3개월 이내가 6개 보육시설 중 3개소(50%), 3개월 이상 6개월 이내가 5개 보육시설 중 3개소(60%), 6개월 이상이 87개 보육시설 중 61개소(70.1%)로 나타났다. 대장균군 검출율은 6개월 이내에는 검출되지 않았으나 6개월 이상이 87개 보육시설 중 5개소(5.7%)로 나타났다. 자외선 살균기의 미생물 오염도는 램프 교체 주기가 길어질수록 미생물 오염도가 높게 나타났다. 또한 자외선 램프 교체 주기가 6개월 이상인 87개 보육시설 중 23개소(26.4%)의 자외선 살균기 반사판에는 물기가 있고 청소상태가 불량한 것으로 나타났다. 이러한 결과를 종합해 볼 때 보육시설에서 사용 중인 자외선 살균기의 위생관리를 위해 주기적인 청소 와 자외선 램프 교체가 필요한 것으로 판단된다. 또한 보육시설 급식담당자들에게 자외선 살균기 청결과 램프 교체에 대한 지속적인 교육이 필요할 것으로 판단되었다.

• Structural Engineering and Mechanics
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• 제49권3호
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• pp.311-327
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• 2014

The safety relating to leakage of water and pitch instability of ship chambers of the full balanced hoist vertical shiplifts has been the focus of adoption of the type of vertical shiplifts. This paper aims to remove the doubts through theoretical and engineering researches. The leakage and pitch stability of ship chambers of full balanced hoist vertical ship lifts are investigated on the basis of theoretical analysis and exploration of engineering measures. Regarding the issue of leakage of ship chambers, a mathematical model on leaking process is built and corresponding formula and coping measures are obtained which can be applied in control program of ship lifts by linking with monitoring. The concept of safety grade is put forward to seek the best technical and economic index and the corresponding technical measures are for different grades of ship lift is suggested. For the issue of pitch instability, a methodology of combining theoretical deduction and summary of achievements of design and operation of the type of the full balanced hoist shiplifts is adopted, and the formula for design about pitch stability of ship chambers is derived.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.97-103
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• 2002

Vibration isolation technology using an air spring and laminated rubber bearing is widely used because it has excellent vibration isolation characteristics. In the part of that, we usually make use of the self-damped air suing. It is occupied two chambers, restrictor, diaphragm and load plate. Two chambers contain compressed air and the volume of chambers and the area of load plate give a definition of stiffness and load. The restrictor and the volume ratio of two chambers give a definition of damping ratio. The conventional model of restrictor is made of one orifice and it causes turbulent flow in the orifice at the region of large deflection. The stillness of air suing is larger and the damping is lower in the region of large deflection. In the multi-orifice case, the stiffness is similar to air spring with one orifice but damping ratio is larger than conventional air spring. And damping ratio is smaller than conventional air suing in small deflection region. Deflection is small in the region of high frequency so small damping is better than large damping. As a result, we can reduce the storage stiffness of air suing in the wide region of deflection and increase the damping ratio in the region of large deflection. After this, we will try to and the relation of Reynolds Number and Flow Resistance then we are going to make another restrictor for air spring to improve damping ratio and stiffness.

• 한국철도학회논문집
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• 제12권5호
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• pp.806-810
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• 2009

병원, 호텔 및 철도역사 등과 같은 대형의 건물 및 차량내부에 사용되는 공조 시스템은 일반적으로 높은 소음을 발생시킨다. 이러한 공조용 발생소음을 저감시키기 위해서 흡음재가 부착된 쳄버를 공기 시스템에 설치한다. 그러나 이러한 쳄버에 설치된 흡음재는 유리섬유 혹은 폴리우레탄 폼이 많이 사용되기 때문에 최근에는 환경적 문제를 야기한다. 이러한 문제를 해결하기 위해서 환경친화적인 다공판 시스템이 내장된 소음쳄버를 개발하였다. 이 소음쳄버는 기존의 소음쳄버에 비해서 중고주파수 영역에서 통일한 소음저감 성능을 나타내지만, 200Hz~400Hz 영역에서는 최고 8dB(A)까지 소음저감 효과가 있다.