• 한국소음진동공학회논문집
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• 제15권11호
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• pp.1248-1254
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• 2005

L/UL(Load/unload) mechanism has been widely used in SFF(Small form factor) HDD because L/UL technology has many advantages such as an increase of areal density, reduction of power consumption and improvement of shock resistance. In this system, the most important design goal is no slider-disk contact and fast air-hearing breaking during L/UL process. To do so, we should consider many design parameters related to L/UL system. The ramp shape is the most dominant component among parameters which dramatically affect the L/UL performance. This paper makes an advanced ramp model using ANSYS/LS-DYNA. Through this FE model, this paper investigates the effect of initial ramp slope and location of air-bearing breaking. From the experiment for three different ramps, we also verify that experimental results agree with simulation results. We conclude that the ramp design should have small ramp slope at the moment which a suspension tap contacts with ramp and large ramp slope after air-bearing breaking in order to improve L/UL Performance.

• 한국기계가공학회지
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• 제18권10호
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• pp.54-59
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• 2019

The final reduction drive in tactical vehicles has a wear-pad that helps to maintain adequate end floating when the hub assay operates. The input axis and sun gear move repeatedly with the axis when tactical vehicle is operating. The hub assay is designed so that the wear pads won't seize during operation. Seizure of the wear pads during operation results in oil leakage. In our study, the fault mechanism was analyzed to prevent the seizure of the wear pads and an optimal design for the shape and material of the wear-pad was explored. We then observed the changes in temperature, shape, and material of several important parts.

• 한국지형학회지
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• 제26권2호
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• pp.15-27
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• 2019

This study tries to reveal transport mechanism and origin of components from fluvial terrace deposits in Danyang and Geum River basins, through grain size partitioning using the Weibull function. Grain size parameters suggest that the samples analyzed in this study can be grouped into the coarse, fine and medium samples. The coarse samples are partitioned into three or four components. More than 65% of the coarse samples consist of components by suspension and saltation by fluvial process, while components by attachment to coarse grains or aggregates and/or by individual grains deposited under non-flow condition are also found in the coarse samples. The fine samples consist of four components and components found in loess deposits in Korea occupy >70%, suggestive of the same transport mechanisms (westerlies and winter monsoon) and common source areas with loess deposits in Korea. However, components by aeolian process from local sources as well as by fluvial process are also found in the fine samples. The medium samples are partitioned into components with similar sizes to the coarse and fine samples, respectively.

• 식물조직배양학회지
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• 제27권1호
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• pp.57-61
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• 2000

식물배양세포의 항산화기구를 이해하기 위하여 다양한 유도조건에서 확립된 24종의 세포주를 대상으로 환원형 (GSH)과 산화형 (GSSG)의 glutathione 함량을 조사하였다. 배양세포의 전체 glutathione 함량 ($\mu$g/g cell fresh wt)은 98$\pm$27로 식물종에 따라 큰 차이가 없었다. 배양세포의 환원형 GSH과 산화형 GSSG의 평균함량 ($\mu$g/g fr wt)은 각각 72$\pm$20와 26$\pm$10을 나타내었다. 배양세포의 전체 glutathione 중에서 평균 환원형 GSH는 약 73%를 차지하였다. 황금 (Scutellaria baicalensis)배양세포의 현탁배양에 따른 GSH 함량 ($\mu$g/g cell fresh wt)은 계대배양부터 대수증식기까지는 계속하여 감소하여 세포생장 정지기인 배양후 13일에는 84까지 감소한 후 다시 증가하였다가 배양후기에는 크게 감소하였다. 한편 GSSG의 함량 ($\mu$g/g cell fresh wt)은 오히려 대수증식기까지는 증가하여 배양후 13일에는 31을 나타내었고 배양후기인 25일에는 48로 오히려 산화형 GSSG의 비율이 높았다. 이러한 결과는 GSH와 GSSG의 비율이 배양세포의 생장과 항산화기구에 주요하게 관여하고 있음을 시사한다.

• 대한약리학회지
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• 제18권1호
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• pp.55-63
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• 1982

Lipid peroxidation is the reaction of oxidative deterioration of polyunsaturated lipids and this peroxidation involves the direct reaction of oxygen and lipid to form free radical intermediates, which can lead to autocatalysis. As results of the extensive studies on the lipid peroxidation by many authors, the relationship between lipid peroxidation and the drug metabolizing system as well as the actions of free radicals on the peroxidation was reasonably well known. For a long time, the mechanism of hepatotoxicity of $CCl_4$ was not clearly understood. However, it is now quite well established that $CCl_4$ is activated in vivo to a free radical which is a highly reactive molecule. Therefore, lipid peroxidation which induces the reduction of cytochrome P-450 and aminopyrine demethylase activity is known as decisive event of $CCl_4$ hepatotoxicity. On the other hand, it was also reported that singlet molecular oxygen produces lipid peroxidation in liver microsomes. In this study the effects of benzoyl peroxide on the lipid peroxidation and drug-metabolizing enzyme were examined. Benzoyl peroxide mixed with starch and phosphates etc. is usually used as a food additive for flour bleaching and maturing purpose because of its oxidative property. Albino rats were used for the experimental animals. Benzoyl peroxide was suspended in soybean oil and sesame oil and administered intraperitoneally or orally. TBA value and aminopyrine demethylase activity were determined in liver microsomal fraction and serum. The results were summerized as following. 1) Body weights of animals administered benzoyl peroxide suspension were decreased while that of oil administered group were increased. 2) The activity of aminopyrine demethylase was generally decreased in animals administered oil suspension of benzoyl peroxide. Furthermore, the marked reduction of the enzyme activity was observed in animals administered benzoyl peroxide intraperitoneally. 3) Generally, microsomal TBA values as well as serum TBA were significantly elevated in benzoyl peroxide group in comparison with the control group. However, the more remarkable increase of serum TBA than microsomal TBA was observed in animals administered orally for 6 days. 4) Specifically, the changing pattern of TBA value was notable in serum rather than in liver microsome by intraperitoneal administration of benzoyl peroxide.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.150-150
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• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• 식물조직배양학회지
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• 제22권5호
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• pp.283-290
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• 1995

미나리의 체세포 배발생 조건 및 기작을 구명하고자 배발생 캘러스의 획득에 적합한 시료와 배지를 구명하고 배발달의 과정을 관찰하여 본 결과, 기내 식물체 확보를 위한 미나리의 경정배양은 발생한 줄기 수와 생육상태로 보아 BA가 0.1 - 0.5 mg/L 첨가된 MS배지가 적합하였으며 배발생 캘러스의 발생은 배유와 함께 채취ㆍ배양한 유배를 2,4- D가 1 mg/L 첨가된 배지에서 2 개월간 배양하였을 때 발생하였다. 기내에서 생장한 줄기와 엽병을 배양하였을 경우는 치상후 2과에 엽병의 절단 부위에서 발생한 캘러스는 모두 배발생 캘러스가 아니였으나 치상 후 6 - 8주에 줄기와 엽병의 표피부위에서 발생한 캘러스는 배발생 캘러스이었다. 배발생 캘러스는 계대배양에 의하여 대양 증식이 가능하며 이들은 배발생 캘러스와 비배발생 캘러스를 동시에 형성하였다. 비배발생 캘러스는 다양한 생장조절제를 첨가한 액체 및 고체배지에 반복 및 지체배양하여도 배발생 캘러스로의 분화는 일어나지 않았다. 비배발생 캘러스는 고체배지에 배양하면 쉽게 증식되어 뿌리를 분화하며, 액체배지 에 현탁배양할 경우에는 단세포로 단리되고, 다시 이들은 작은 원형세포괴를 형성한 후 단지 뿌리만을 발생하였다.

• 동의신경정신과학회지
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• 제22권2호
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• pp.129-146
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• 2011

Objectives : The purpose of this study was to characterize the putative antidepressant and antianxiolytic effects of the 70% ethanol extract of Polygala japonica(EEPJ) using animal's behavioral experiment in mice. Methods : The effect of EEPJ on the anxioty and depressive disorder was investigated via mice's behavioral experiment like Elevated plus-maze, Horizontal wire test, Open field test, Forced swimming test, Tail suspension test, and it was happen via any mechanism by WAY 100635, a 5-HT1A receptor antagonist and by Flumazenil, a GABAA antagonist Results : 1. In the EPM, single treatments of the EEPJ(200 and 400mg/kg) had usefully antianxiolytic effects versus vehicle, which was medicated via the serotonergic nervous system. 2. In the HWT, single treatments of the EEPJ were no changes in the myorelaxant effects versus vehicle. 3. In the OFT, single treatments of the EEPJ were no changes in the locomotor activity versus vehicle. 4. In the FST, single treatments of the EEPJ(50mg/kg) significantly reduced the immobility time versus vehicle. 5. In the TST, single treatments of the EEPJ(50mg/kg) significantly reduced the immobility time versus vehicle. Conclusions : These results indicate that EEPJ is an effective antidepressant and antianxiolytic activity in mice, and it might be usefully applied for prevention and treatment of depressive disorder through evolutive study like development of various experimental models.

• The Korean Journal of Physiology and Pharmacology
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• 제3권4호
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• pp.439-445
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• 1999

This study is to investigate the mechanism of inhibitory effect of imipramine on the calcium utilization in single cells isolated from canine detrusor. 2 mm thick smooth muscle chops were incubated in 0.12% collagenase solution at $36^{circ}C,$ and aerated with 95% $O_2/5%\;CO_2,$ and then cell suspension was examined. Acetylcholine (ACh) evoked a concentration-dependent contraction of the isolated detrusor cells in normal physiologic salt solution (PSS), and the ACh-induced contraction was significantly inhibited by imipramine. In $Ca^{2+}-free$ PSS, ACh-induced contraction was less than those in normal PSS and it was not affected by the pretreatment with imipramine. $Ca^{2+}-induced$ contraction in $Ca^{2+}-free$ PSS was supressed by imipramine, but addition of A 23187, a calcium ionophore, overcomed the inhibitory effect of imipramine. High potassium-depolarization (40 mM KCl) evoked cell contraction, which was inhibited by imipramine. Caffeine, a releasing agent of the stored $Ca^{2+}$ from sarcoplasmic reticulum, evoked a contraction of the cells that was not blocked by the pretreatment with imipramine. These results suggest that imipramine inhibits the influx of calcium in the detrusor cells through both the receptor-operated- and voltage-gated-calcium channels, but does not affect the release of calcium from intracellular storage site.

• 한국재료학회지
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• 제11권8호
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• pp.679-684
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• 2001

천연흑연은 단위구조가 탄소육각망평면이 평행하게 배열된 층상으로 전기전도도 및 윤활성이 우수하나 소수성이 매우 강하며, 표면화학적 목성이 거의 없기 때문에 다른 물질과 흡착이 쉽게 일어나지 않아 분산이 매우 어려운 물질이다. 따라서 본 연구에서는 제타전위를 이용하여 흑연에 ABDM을 흡착시켜 표면특성을 소수성에서 친수성으로 변화시키고 수중현탁액 중에서 흑연입자의 분산 메커니즘을 DLVO이론을 이용하여 설명하였다. 흑연의 제타전위가 22.5mV가 되도록 ABDM의 흡착량 (20mg/g) 및 조건 (PH 10에서 12시간 흡착)을 만족시키면 분산안정성 (T$_{1/2}$) 이 44.5시간인 고분산성 흑연 현탁액을 제조할 수 있다.