• Journal of Nutrition and Health
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• 제18권4호
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• pp.283-292
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• 1985

대학 급식 시설의 위생 실태를 평가하기 위해서 오뎅국의 생산 과정을 통한 소요시간 및 온도상태 측정 pH 및 Aw측정, 미생물 검사를 실시하여 HACCP model에 의해 분석, 평가한 결과는 다음과 같다. 1 )소요시간 및 온도상태 측정 결과. 재료들의 조리후 실온방치 단계와 국물의 보온단계에서 철저한 관리가 요구된다. 2 ) pH및 Aw측정 결과, 대부분의 단계가 미생물 증식에 적합한 조건이었다. 3 )음식에 대한 미생물 분석 결과, 재료들의 미생물적 품질이 대체로 낮았다. 또한 조리후 급식전 보관단계에서 장시간 실온에 방치되므로 미생물의 오염 및 증식 기회가 많았다. 4 ) 오뎅국 생산에 사용되는 기구, 설비, 용품 및 용기에 대한 미생물 분석 결과 뚝배기, 장갑, 행주와 도마에 대한 즉각적인 시정이 요구된다. 5 ) 이상에서 오뎅국 생산 단계에서의 critical control points는 재료, 전처리, 후처리 및 급식전 보관단계로 지적되었다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.70-75
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• 2004

In this study, the pattern of lens aberration was studied at different injection molding conditions such as injection speed, holding pressure, holding pressure time, mold temperature and cylinder temperature and, then, the results were analyzed with a laser interferometer. It was demonstrated that optimal condition of lens aberration could be achieved by adjustment of injection molding conditions.

• Journal of Communications and Networks
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• 제8권1호
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• pp.28-37
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• 2006

State-dependent call admission control (SDCAC) is proposed to make efficient use of scarce wireless resource in a hierarchical wireless network with heterogeneous traffic. With SDCAC, new calls are accepted according to an acceptance probability taking account of not only cell dwell time but also call holding time and system state (i.e., occupied bandwidth). An analytical method is developed to calculate performance measures of interest, e.g., new call blocking probability, forced termination probability, over. all weighted blocking probability. Numerical results with not only stationary but nonstationary traffic loads are presented to show the robustness of SDCAC. It is shown that SDCAC performs much better than the other considered schemes under nonstationary traffic load.

• 한국주조공학회지
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• 제13권3호
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• pp.276-284
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• 1993

The interfacial phenomena between intermetallic compounds and Al matrix have been studied at $680^{\circ}C$ for various holding time under argon atmosphere. Model experiments were performed using Fe, Ni and Ti wire to observe the interfacial phenomena. The interfacial phenomena between intermetallic compounds and Al matrix were analysed by optical microscope, SEM and EDX. The results of EDX and XRD showed that the interfacial zones of intermetallic compounds/Al matrix were composed of several intermetallic layers. The reaction layer was varied with holding time and heating temperature. The investigation of interfacial zones in the specimen as a function of heat treatment time at $680^{\circ}C$ indicated that the best heat treatment condition for squeeze casting was $680^{\circ}C$ for 5min.

• Journal of Welding and Joining
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• 제19권3호
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• pp.325-333
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• 2001

The effect of base metal grain size on isothermal solidification behavior of Ni-base superalloy, CMSX-2 during transient liquid phase (TLP) bonding was investigated employing MBF-80 insert metal. TLP-bonding of single crystal. coarse-grained and fine-grained CMSX-2 was carried out at 1373∼1548k for various holding time in vacuum. The eutectic width diminished linearly with the square root of holding time during isothermal solidification process for single crystal, coarse-grained and fine-grained base metals. The completion time for isothermal solidification decreased in the order ; single crystal, coarse-grained and fine-grained base metals. The difference of isothermal solidification rates produced when bonding the different base metals could be explained quantitatively by the effect of base metal grain boundaries on the apparent average diffusion coefficient of boron in CMSX-2.

• 한국식품저장유통학회지
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• 제11권3호
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• pp.313-318
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• 2004

원료 양송이의 수확시기 및 보관 기간에 따른 신선편이 가공적성을 비교키 위하여 계절별로 수확한 양송이를 각각2$^{\circ}C$ 에 보관하면서 주기적으로 일정량씩을 취하여 각각 절단한 후 5$^{\circ}C$ 에 방치하면서 표면의 갈변진행정도와 총 페놀화합물 함량 변화를 조사하였다. 원료 양송이의 호흡률은 여름철 및 가을철에 수확한 것이 9.55$\~$10.47 mLCO$_{2}$kg$\cdot$hr로 봄철 및 겨울철에 수확한 것에 비해 낮았고, 중량감소율은 봄에 수확한 양송이가 가장 낮았다. 원료상태로 보관한 양송이의 표면색은 여름철 양송이가 가장 빨리 변하였으며 봄, 가을 및 겨울철에 수확한 양송이는 비슷한 수준을 나타내었다. 절단 처리시 여름철 수확한 양송이가 다른 계절양송이에 비해 표면색 변화가 가장 심하였으며, 7일 이상 보관한 원형 양송이는 절단처리 전 표면색 열화 및 절단처리 후 빠른 갈변으로 인하여 가공적성이 낮았다.

• 한국재료학회지
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• 제7권2호
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• pp.145-151
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• 1997

AI-xSi/ySiC( x:6~18wt%, y: 3~9wt%, SiC 입자크기: $10~28{\mu}m$) 복합재료를 재용해한 후 항온 유지하고 응고 시킬때 SiC 입자가 몰드의 하부로 침강하는 현상을 계통적으로 조사하였다. AI-Si/SiC 복합재료 용탕을 항온으로 유지하면 입자가 없는 지역은 유지시간이 약 처음 30분 동안 빠르게 증가한다. SiC 입자가 크기가 클수록 SiC입자의 크기가 클수록 SiC입자의 침강속도가 빠르다. 또한 복합재료중 철가한 SiC 입자의 부피분율이 증가하면 입자의 침강속도는 감소한다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.709-715
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• 2006

The effects of thermal cycle condition and applied stress on the intergranular corrosion in austenitic 316 type stainless steels were investigated. Specimens were solution-treated at 1100$^{\circ}C$ for one hour and then sensitized in the temperature range of $500{\sim}800^{\circ}C$ by holding $2{\sim}300s$ with a various applied stresses of $0{\sim}8kg/mm^2$. Degree of sensitization. DOS %, was measured through polarization curve by electrochemical DL-EPR test. Microstructural observations were also conducted DOS % increased with an increase of sensitization temperature and/or holding time. Increase of applied stress resulted in increase of DOS % and more corroded surface because of acceleration of intergranular corrosion and fine grain size due to the stress. Cr depleted zone near grain boundary was observed. The amount of depletion was profounded with an increase of sensitization temperature, holding time and applied stress. $M_{23}C_6$ carbides were precipitated discontinuously at grain boundary. However, its amount was relatively small in the thermal cycle condition of 800$^{\circ}C$, 300sec and 4kg/mm$^2$.

• 한국재료학회지
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• 제19권12호
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• pp.680-685
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• 2009

Using a polyurethane foam replica method, porous hydroxyapatite scaffolds (PHS) were fabricated using conventional and microwave sintering techniques. The microstructure and material properties of the PHS, such as pore size, grain size, relative density and compressive strength, were investigated at different sintering temperatures and holding times to determine the optimal sintering conditions. There were interconnected pores whose sizes ranged between about 300 ${\mu}m$ and 700 ${\mu}m$. At a conventional sintering temperature of 1100$^{\circ}C$, the scaffold had a porous microstructure, which became denser and saw the occurrence of grain growth when the temperature was increased up to 1300$^{\circ}C$. In the case of microwave sintering, even at low sintering temperature and short holding time the microstructure was much denser and had smaller grains. As the holding time of the microwave sintering was increased, higher densification was observed and also the relative density and compressive strength increased. The compressive strength values of PHS were 2.3MPa and 1.8MPa when conventional and microwave sintering was applied at 1300$^{\circ}C$, respectively.

• Journal of Welding and Joining
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• 제7권4호
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• pp.30-37
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• 1989

Effect of heat treatment on mechanical properties of an overlay weldment was investigated. Over welding was carried out on the structural C-Mn mild steel substrate to take required test specimens. Shielded metal arc welding process with 13Cr-0.2Ni stick electrode was applied. The heat treatment temperatures and holding times were $450{\circ}C., 550{\circ}C., 650{\circ}C., 750{\circ}C., 850{\circ}C.$ and 0.5hr, 2hr, 10hr, respectively. Mechanical tests and microscopic inspection were also carried out to investigate welds soundness. Test results indicated that carbon migration was dominant near bonded zone. At temperature of around 650.deg. C, carburized layer and decarburized layer were formed remarkably along overlay welds region and C-Mn mild steel region, respectively. The wideth of these layers became wider with increasing heat treatment temperature and/or holding time at the elevated temperature, and this relationship agreed with Larson-Miller parameter. Side bending test results demonstrated that the crack free region of overlay welds could be deduced from the relationship between temperature and holding time.