• Journal of Advanced Marine Engineering and Technology
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• 제34권1호
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• pp.30-36
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• 2010

다중관식 헬리컬 코일형 가스냉각기내 $CO_2$의 열유량과 압력강하에 대해서 실험적으로 조사하였다. $CO_2$와 냉각수의 유량은 각각 0.06~0.075kg/s이고, 가스냉각기의 냉각압력은 8~10 MPa이다. $CO_2$의 열유량은 냉각수 질량유량, $CO_2$의 질량유량과 냉각압력에 비례하여 증가한다. $CO_2$의 압력강하는 냉각수와 $CO_2$의 질량유량이 감소할수록 감소하지만, $CO_2$의 냉각압력이 증가할수록 감소한다. 다중관식 헬리컬 코일형 가스냉각기내 $CO_2$의 열유량과 압력강하는 각각 이중관식 가스냉각기보다 상당히 높게 또는 낮게 나타났다. 따라서 다중관식 헬리컬 코일형 가스냉각기에 $CO_2$를 적용하는 경우에는 가스냉각기의 고효율화, 고성능화, 컴팩트화가 가능할 것이다.

• 한국식품과학회지
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• 제30권5호
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• pp.1024-1028
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• 1998

압출성형 방법에 의하여 고아밀로즈 옥수수전분으로부터 제조된 난소화성 전분의 분자구조적 특징을 규명하기 위하여 X-ray 회절 실험과 $^{13}C\;NMR$ 분석을 시도하였다. X-ray를 이용한 전분구조분석에서 전분의 결정 구조 비율은 압출성형시 낮은 바렐온도 $(100^{\circ}C)$에서는 원료투입 수분함량 증가시$(25{\sim}45%)$ 6.08%에서 8.37%로 약간 증가하는 경향을 보였으며, 시료간의 큰 차이는 보이지 않았다. X-ray pattern에서 $Peak\;2{\theta}$ 비교시 고 아밀로즈 압출성형물이 투입원료 수분함량이 감소하고$(45\;{\rightarrow}\;25%)$, 바렐온도가 상승하면$(120\;{\rightarrow}\;140^{\circ}C)$ 결정격자 간격 d가 작은 조밀한 결정구조가 붕괴되고 d가 증가한 느슨한 결정구조로 변형됨을 알 수 있다. $4^{\circ}C$ 저장중 압출성형된 고아밀로즈 옥수수 전분 결정 비율은 4주 저장 후에$(6.3{\sim}8.3%)$에서$(4.5{\sim}5.8%)$로 약간 감소되는 결과를 나타내었다. $^{13}C\;NMR$ 실험을 통한 이중나선 구조 비율은 바렐온도 상승시, 투입원료 수분함량이 적을수록 그 비율이 60%에서 42.5%로 감소되었고 저장 중에는 큰 변화를 보이지 않았다. 전보에서 발표한 pancreatin에 의한 난소화성 전분 수율과 비교해 보면, 이중 나선구조 구성 비율은 저장전에는 서로 상관관계가 있어 보이나 저장중 변화에서는 서로 연관성을 나타내지 않았다. 즉, 저장중 난소화성 전분수율의 증가는 X-ray 분석에 의한 상대적 결정성화가 약간 감소하면서 이중나선구조 비율에는 변화가 없는 특징적 분자구조 변형에 의한 것이라 사료된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.846-849
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• 2000

세라믹 재료는 높은 강도 및 결도를 갖는 기계적 성질로 인하여 연삭가공에는 다이아몬드를 지립으로 하는 초지립 숫돌이 사용된다. 다이아몬드는 일반지립에 비하여 내마모성이 월등하게 높다는 사실로부터 숫돌의 트루잉 및 드레싱 작업이 극히 곤란한 것은 주지의 사실이다.(중략)

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.263-267
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• 2009

Cylindrical monopole antenna is one of most promising candidates for multi-band applications such as PCS, WLAN, DMB, and UWB wireless services. In this research, we demonstrate that there exist two types of current distributions according to the exciting frequency in a double band cylindrical monopole antenna, in which double resonance is achieved by adjusting the coupling structure of the antenna base. The operating modes of current distributions are identified from CST software simulations, the standing wave mode in a lower band and the traveling wave mode in a higher band. Also it is noticed that the mode behavior is quite similar to a helical antenna, a standing-wave (resonance) mode and a traveling-wave (non-resonance) mode according to the electrical dimensions of antenna. The effective ranges for operating modes and design formulas of the double band antenna are derived from simulation and measured results.

• Bulletin of the Korean Chemical Society
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• 제35권11호
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• pp.3267-3274
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• 2014

In order to investigate the effects of the double replacement of $\small{L}$-Pro, $\small{D}$-Pro, $\small{D}$-Leu or Nleu (the peptoid residue for Leu) in the hydrophobic face (positions 9 and 13) of amphipathic ${\alpha}$-helical non-cell-selective antimicrobial peptide $L_8K_9W_1$ on the structure, cell selectivity and mechanism of action, we synthesized a series of $L_8K_9W_1$ analogs with double replacement of $\small{L}$-Pro, $\small{D}$-Pro, $\small{D}$-Leu or Nleu in the hydrophobic face of $L_8K_9W_1$. In this study, we have confirmed that the double replacement of $\small{L}$-Pro, $\small{D}$-Pro, or Nleu in the hydrophobic face of $L_8K_9W_1$ let to a great increase in the selectivity toward bacterial cells and a complete destruction of ${\alpha}$-helical structure. Interestingly, $L_8K_9W_1$-$\small{L}$-Pro, $L_8K_9W_1$-$\small{D}$-Pro and $L_8K_9W_1$-Nleu preferentially interacted with negatively charged phospholipids, but unlike $L_8K_9W_1$ and $L_8K_9W_1$-$\small{D}$-Leu, they did not disrupt the integrity of lipid bilayers and depolarize the bacterial cytoplasmic membrane. These results suggested that the mode of action of $L_8K_9W_1$-$\small{L}$-Pro, $L_8K_9W_1$-$\small{D}$-Pro and $L_8K_9W_1$-Nleu involves the intracellular target other than the bacterial membrane. In particular, $L_8K_9W_1$-$\small{L}$-Pro, $L_8K_9W_1$-$\small{D}$-Pro and $L_8K_9W_1$-Nleu had powerful antimicrobial activity (MIC range, 1 to $4{\mu}M$) against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Pseudomonas aeruginosa (MDRPA). Taken together, our results suggested that $L_8K_9W_1$-$\small{L}$-Pro, $L_8K_9W_1$-$\small{D}$-Pro and $L_8K_9W_1$-Nleu with great cell selectivity may be promising candidates for novel therapeutic agents, complementing conventional antibiotic therapies to combat pathogenic microorganisms.

• Journal of Advanced Marine Engineering and Technology
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• 제8권2호
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• pp.74-80
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• 1984

In the reduction gears for marine propulsion engine such as turbine or high speed diesel engine, the standard involute double helical gears are generally used. However the addendum modification gear can be used in the reduction gear as it has flexibility for gear design on the tooth strength, scoring and operating noise. In this case, the determination of gear shaft bearing load is difficult by the alternation of operating pressure angle. In this paper, the formulas of bearing load according to the arrangements of the reduction gears are derived and the diagrams of operating pressure angle according to the modification coefficient are presented.

• Nuclear Engineering and Technology
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• 제48권4호
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• pp.1022-1035
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• 2016

A double-tube once-through steam generator (DOTSG) consisting of an outer straight tube and an inner helical tube is studied in this work. First, the structure of the DOTSG is optimized by considering two different objective functions. The tube length and the total pressure drop are considered as the first and second objective functions, respectively. Because the DOTSG is divided into the subcooled, boiling, and superheated sections according to the different secondary fluid states, the pitches in the three sections are defined as the optimization variables. A multi-objective optimization model is established and solved by particle swarm optimization. The optimization pitch is small in the subcooled region and superheated region, and large in the boiling region. Considering the availability of the optimum structure at power levels below 100% full power, we propose a new operating scheme that can fix the boundaries between the three heat-transfer sections. The operation scheme is proposed on the basis of data for full power, and the operation parameters are calculated at low power level. The primary inlet and outlet temperatures, as well as flow rate and secondary outlet temperature are changed according to the operation procedure.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.166-173
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• 2006

This study investigates a heavy duty diesel engine with swept vol. 12.6L, 4cycle-OHC type to verify the effects of the performance and exhaust gas emission according to the variable specifications of both swirl ratio and flow coefficient in inlet port, combustion bowl and fuel injection system. To meet the high BMEP and stringent exhaust emission standard, a turbocharger with wastegate and an intercooler were installed in the engine. Helical port, major design parameters for combustion chamber and electronic fuel injection pump with 1,000bar were reviewed and applied. Confirmation tests were also performed to meet the target value, $NO_x$ 5.0g/kWh and PM 0.1g/kWh of Euro3 exhaust emission legislation. The results of this study show that not only is it effective to use a relatively bigger bowl size for controlling rapid burning condition due to the decreased in-bowl swirl, but also to use a concave cam with double injection rates to decrease $NO_x$.

• Parasites, Hosts and Diseases
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• 제23권2호
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• pp.269-284
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• 1985

The metabolism of Entamoeba histolytica would be affected by various environmental factors, and alteration of the environment was known to afEect the fine structure of 5. histolytica. The present study was designed electronmicroscopically to investigate the ultrastructure and enzyme activities in the aEonic and conventional strains of 5. histolytica. The trophozoites of axenically cultivated HK-9 strain and conventional YS-27 and YS-49 strains of 5. histolytica were collected and liKed with 4% paraformaldehyde/0.1M cacodylate buffier(pH 74), After washing them by centrifugation, 1% warm agar was added in the sediment. Solidified agar with the trophozoites was cut into $lmm^3$ cubes, and incubated in the various substrates to observe enzyme activities. Then, the specimen was post-fixed with 3% glutaraldehyde/0.1M cacodylate buffer (PH 7.4) and 1% osmium tetroBide/0.1M cacodylate buffier (pH 7.4) , dehydrated in ascending ethanol series and embedded in epoxy resin. These were sectioned on an ultramicrotome and observed with a transmission electronmicroscope. The procedures for the observation of the fine structure were same as the above, except for the incubation in the substrate. The sections were stained with uranyl acetate and lead citrate. For the observation of the surface of the amoebae, scanning-electronmicroscopy was carried out. The results obtained in the present study are summarized as follows: 1. The fuzzy coat around double-layered plasma membrane of 5. histolytica was more irregularly and densely distributed in the conventional strains (YS-27, YS-49 strains) than in the axonic strain (HK-9 strain). 2. The endosomes, button bodies and chromatin material were surrounded by a double-layered nuclear membrane having scattered nuclear fores. The paranuclear body, mono- or double-layered vacuoles, vacuolar membrane whorls, rosette-like cylindrical bodies, aggregation of cylindrical bodies and helical bodies were found in the cytoplasm of the amoebae. Helical bodies and glycogen granules were generally abundant, while a few smooth endoplasmic reticula were observed in the cytoplasm. 3. Alkaline phosphatase activity was mainly demonstrated in the plasma membrane, limiting membranes of vacuoles and smooth endoplasmic reticula. ATPase activity was observed in the nucleus, limiting membranes of vacuoles and vacuolar membrane whorls. 4. Acid phosphatase activity was commonly demonstrated in the limiting membranes an contents of vacuoles, Iysosome-like organelles, plasma membrane and the button bodies in the nucleus. The activity was more weakly demonstrated in the HK-9 strain than in the other conventional strains of 5. histolytica. No peroBidase activity was observed in the amoeba strains employed in the present study. 5. With a scanning electron-microscope, no distinct structural differences were observed between the amoeba strains. All the trophozoite forms of the amoebae showed crater-like depressions and rugged features on the outer surface.

• 한국어류학회지
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• 제9권1호
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• pp.114-120
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• 1997

자연상태에서 어류의 척추골 이상을 조사하기 위하여 1995년 8월과 1996년 7월 및 8월에 낙동강의 일차지류인 금호강에서 채집한 잉어과 어류 5종의 치어를 대상으로 종별 및 체장별로 척추골 변형의 형태와 그 빈도를 조사하였다. 치어에서 나타난 척추골 변형의 형태는 척추굴곡, 척추융합, 나선형 봉합선을 가진 척추, 하나 이상의 가시를 중복하여 가지는 척추 등 4가지 유형이었고 척추골 변형의 발생 빈도는 종에 따라 다소 차이가 있었다. 조사대상 종 모두에서 하나 이상의 가시가 중복되어 나타나는 척추변형은 11.72~21.11%로 가장 높은 빈도를 보였고 척추융합은 4.69~7.68%로 나타났다. 융합의 형태는 2개의 추골이 서로 융합된 빈도가 가장 높았다. 또한 추골 융합은 미부 봉상골 바로 앞의 추골에서 발생 빈도가 종에 따라 67.09~86.71%로서 다른 부위에 비해 높았다. 척추굴곡은 0.02~0.15%, 나선형 봉합선을 가진 척추는 0.02%의 빈도로 나타났다. 조사된 어류에서 나타난 척추이상의 형태를 종별로 보면 긴몰개(Squalidus gracilis majimae), 참붕어(Pseudorasbora parva), 붕어(Carassius auratus)는 척추융합과 하나 이상의 가시를 중복하여 가지는 척추변형만 나타났으며 참몰개(Squalidus chankaensis tsuchigae)는 이 두 척추변형 외에 척추굴곡이 함께 발견되었고 갈겨니(Zacco temmincki)는 나선형 봉합선을 가진 척추변형도 나타나 조사된 어류 중에서 가장 다양한 척추변형의 형태를 보였다. 척추융합과 하나 이상의 가시를 중복하여 가지는 척추변형의 빈도는 체장과는 관계가 없었으며 척추굴곡과 나선형 봉합선은 체장 20mm 이하의 치어에서만 나타났다.