• 한국자동차공학회논문집
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• 제11권5호
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• pp.219-226
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• 2003

The fatigue crack growth behavior of the SA516/60 steel used for pressure vessels was examined experimentally at room temperatures $25^{\circ}C$,$-30^{\circ}C$, $-60^{\circ}C$, $-80^{\circ}C$, $-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. fatigue crack propagation rate da/dN related with stress intensity factor range $\Delta$K was influenced by stress ratio in stable than fatigue crack growth (Region II) with an increase in $\Delta$K. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to the extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are explained mainly by the crack closure and the strengthening due to the plasticity near the crack tip and roughness of the crack faces induced.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.359-365
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• 2002

The fatigue crack growth behavior of the SA516/60 steel which is used for pressure vessels was examined experimentally at room temperature $25^{\circ}C,\;-30^{\circ}C,\;-60^{\circ}C,\;-80^{\circ}C,\;-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. Fatigue crack propagation rate da/dN related with stress intensity factor range ${\Delta}K$ was influenced by stress ratio in stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to tile extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the plasticity induced and roughness induced.

• Tribology and Lubricants
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• 제12권1호
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• pp.56-65
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• 1996

The result of wear test for ceramic materials was assessed by Scf parameter to verify the usefulness of the proposed Scf parameter. Friction and wear tests were carried out with ball on disk type. The materials used in this study were HIPed Alumina $(Al_2O_3)$, Silicon carbide (sic), Silicon nitride $(Si_3N_4)$ and Zirconia $(ZrO_2)$. The tests were carried out at room temperature with self mated couples of ceramic materials under lubricated condition. Turbine oil was used as a lubricant. In this test, increasing the load, specific wear rates and wear coefficients of four kinds of ceramic materials had a tendency to increase. The wear coefficients of ceramic materials were in order of $Al_2O_3, SiC, Si_3N_4, ZrO_2$. Worn surfaces investigated by SEM had residual surface cracks and wear particles caused by brittle fracture. As the fracture toughness of ceramic materials was higher, wear resistance more increased. The roughness of worn surface had correlation with wear rate. The wear rate(W$_{s}$) and Scf parameter showed linear relationship in log-log coordinates and the wear equation was given as $W_s = 5.52 $\times$ Scf^{5.01}$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.1107-1112
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• 2009

Ground anchor should not be used in soft clay, because anchor resistance can not be guaranteed. However, there is a way to increase the capacity of anchors. The pulse powered anchor is an underreamed anchor by using high voltage electrokinetic pulse energy. In this study, a series of field test were carried out in order to find expansion rate related in number of pulse charge. and Anchor pull-out tests were performed at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. Data were analyzed in order to define a relation between expansion rate and ultimate pullout load.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.216-217
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• 2007

In this study, we analyzed the electrical loss characteristics between ribbon and output terminal of constituent material according to electrical resistance during interconnection process of PV module. From this result, the electrical output power reduction rate caused by interaction between ribbon and cell's interconnection was 2.88%. There was 1W electrical output power reduction through the 16 solar cells. So it is expected that the wider size of PV module gives the higher loss in electricity production. Also, the average output power of PV module passed lamination process was increased by 0.081W per one solar cell and the increase rate was 3.7%.PV module's electrical loss before and after lamination process according to constituent material's terminal was 0.49W and 0.50W, respectively.

• Corrosion Science and Technology
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• 제19권6호
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• pp.326-336
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• 2020

Galvalume steel (GL) is widely used in marine and industrial environments. It is characterized by better corrosion resistance than carbon steel. However, corrosion and economic losses may occur as the usage time is increased. Therefore, in this study, an outdoor exposure test of GL for 36 months was conducted across six regions of Korea. Parameters such as corrosion rate, chrominance (color, chroma, and brightness), glossiness, and surface appearance were analyzed. The results showed no significant change in appearance, and the initial corrosion rate was large, but a tendency to decrease with time was observed. Increased outdoor exposure time led to increase in the level of corrosion products. In the case of coastal areas where S, Cl, and other elements were detected, a relatively high decrease in Zn content was observed. Al forms a protective oxide film and exists in the coating layer, but Zn dissolves due to its chemical activity and low potential.

• Membrane and Water Treatment
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• 제4권4호
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• pp.251-263
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• 2013

The internal reflux effect on dialysis through the retentate phase of a countercurrently cross-flow rectangular module is investigated. Theoretical analysis of mass transfer in cross-flow devices with or without recycling is analogous to heat transfer in cross-flow heat exchangers. In contrast to a device without reflux, considerable mass transfer is achievable if cross-flow dialyzers are operated with reflux, which provides an increase in fluid velocity, resulting in a reduction in mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration operated under high reflux ratio.

• Diabetes and Metabolism Journal
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• 제42권6호
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• pp.451-464
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• 2018

Latent autoimmune diabetes in adults (LADA) is a heterogeneous disease characterized by a less intensive autoimmune process and a broad clinical phenotype compared to classical type 1 diabetes mellitus (T1DM), sharing features with both type 2 diabetes mellitus (T2DM) and T1DM. Since patients affected by LADA are initially insulin independent and recognizable only by testing for islet-cell autoantibodies, it could be difficult to identify LADA in clinical setting and a high misdiagnosis rate still remains among patients with T2DM. Ideally, islet-cell autoantibodies screening should be performed in subjects with newly diagnosed T2DM, ensuring a closer monitoring of those resulted positive and avoiding treatment of hyperglycaemia which might increase the rate of ${\beta}-cells$ loss. Thus, since the autoimmune process in LADA seems to be slower than in classical T1DM, there is a wider window for new therapeutic interventions that may slow down ${\beta}-cell$ failure. This review summarizes the current understanding of LADA, by evaluating data from most recent studies, the actual gaps in diagnosis and management. Finally, we critically highlight and discuss novel findings and future perspectives on the therapeutic approach in LADA.

• 대한치과의사협회지
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• 제57권8호
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• pp.464-473
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• 2019

For dental pulp treatment of immature permanent teeth, direct pulp capping or partial/cervical pulpotomy (apexogenesis) procedures can be used if the dental pulp is vital. MTA (Mineral Trioxide Aggregate) is regarded as the first choice dressing material for these procedures because its higher success rate. It can be also used successfully for devitalized dental pulp which has been treated by calcium hydroxide. This apexification procedure with MTA has a few advantage such as short treatment period and increase of resistance against root fracture. Recently, regenerative endodontic treatment was introduced for devitalized immature pulp. It can maintain pulp vitality and lead to continuing root development although the dental pulp was devitalized.

• 한국작물학회지
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• 제49권6호
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• pp.491-495
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• 2004

기존의 내탈립성 참깨들은 우리나라 환경에서의 적응성이 떨어지며 수량성도 낮았으나, 계속적인 개량으로 인해 기존품종보다 내탈립성이 뛰어나면서도 수량성 등 제반 형질이 뒤지지 않는 새로운 내탈립성 참깨의 개발을 목전에 두고 있다. 그러나 앞으로도 계속적인 개량이 필요한 이들 내탈립성 참깨의 효율적인 육성 기술은 아직 부족한 실정이다. 따라서 본 시험에서는 이와 관련된 기술로 참깨 종자의 내탈립성을 나타내는 구체적인 기작 및 효율적인 탈립성 검정 방법 등을 밝히고자 수행하였던 결과를 요약하면 다음과 같다. 참깨 종자의 내탈립성의 원인을 검토한 결과 PA형의 내탈립성은 꼬투리(capsule)내 태좌의 종자 보유력이 크기 때문에 나타난 것으로 추정되었으며, ID형은 꼬투리의 중과피(mesocarp) 두께가 일반 참깨보다 두껍기 때문이었으며, SL형은 꼬투리에 seam이 존재하지 않기 때문이었다. 또한 내탈립성 참깨들은 일부의 개체에서 탈립성이 큰 변이가 나타났는데, 이는 이들 참깨들의 진화방향이 탈립성이 큰 방향임을 의미하는 것으로 판단되었다. 탈립성 측정을 위한 적합한 건조 조건은 상온에서는 참깨 수확 후 최소 20일, $40^{\circ}C$의 건조기 내에서는 10일 이상의 건조기간이 필요한 것으로 나타났다.