• Journal of the Korean Society for Nondestructive Testing
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• v.14 no.2
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• pp.122-131
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• 1994

Journal bearings in the rotating machineries are vulnerable to the contamination or the insufficient supply of lubricating oil, which is likely to be the cause of unexpected shutdown or malfunction of these systems. Various destructive and nondestructive testing methods had been used for the reduction of maintenance cost and the operational safety problems due to the accidents related to bearing damages. In this experimental approach, acoustic emission monitoring is employed to the detection of incipient failure caused by intervention of foreign particles most probable in the journal bearing systems. Experimental schedules for the intervention of foreign particles was composed to be more quantitative and systematic than last study in consideration of minimum oil film thickness and particle size. The experiment was conducted under such designed conditions as inserting alumina particles to the lubrication layer in the simulated journal bearing system. Several parameters such as AE rms level, waveform, AE energy distribution and other AE event parameters are used for analysis and characterization of damage source. The results showed that the history of damage was well correlated with the changes of AE rms level and the type of damage source signal can be verified using other informations such as waveform, distributions of AE parameters etc.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.167-167
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• 2010

반도체는 도핑하지 않으면 대부분 n형을 나타내는 것에 반하여 GaSb는 p형을 보이는 반도체로서, 그 근원은 명확하게 규명되어 있지 않은 상태이다. GaSb의 p형 불순물인 Be은 Ga과 치환 ([$Be_{Ga}$])되므로, p형 전도의 근원으로 추정되는 잔존결함인 [$Ga_{Sb}$]와 그 복합체인 [$Ga_{Sb}-Sb_{Ga}$]와 높은 상관관계를 가질 것으로 예측된다. 본 연구에서는 Be을 도핑한 GaSb:Be 에피층을 MBE 방법으로 성장하여, PL 스펙트럼과 Hall 효과 분석을 통하여 p형 전도의 근원을 조사하였다. 도핑하지 않은 u-GaSb는 DA (deep acceptor)와 함께 A 준위를 나타낸 반면, p-GaSb:Be의 PL 스펙트럼은 Be 도핑농도가 증가함에 따라 FWHM가 줄어들면서 점차 높은 에너지 영역으로 변위하지만 농도가 가장 높은 시료에서는 PL의 FWHM가 증가하면서 에너지는 감소함이 관측되었는데, 이것은 A 피크와 Sb 관련 피크가 경쟁적으로 중첩되어 나타난 현상으로 분석된다. Hall 효과 결과는 유효 전하밀도의 증가에 따라 이동도는 감소하는 전형적인 의존성을 나타내었으며, u-GaSb의 Hall 이동도가 p-GaSb:Be의 값보다 작은 것은 u-GaSb에 잔존하는 DA에 의한 산란 때문으로 해석된다. Gaussian 형태로 분해하여 얻은 A ([$Ga_{Sb}$])와 DA ([$Ga_{Sb}-Sb_{Ga}$]) 및 Be 관련 피크로부터 특정 도핑농도 ($1.2{\times}10^{17}cm^{-3}$)의 시료를 제외한 모든 p-GaSb:Be에는 A 피크가 중첩되고 A와 Be 준위 중간에 Be과의 복합체인 중간상태(intermediate state)인 [$Be^*$]가 존재함이 관측되었는데, 특정 도핑농도에서는 [$Be_{Ga}$]이 우세하지만 더 이상 농도가 증가하면 [$Be_{Ga}$] 준위의 강도는 오히려 감소함을 관측할 수 있었다. 이것은 적정 이상의 Be을 도핑할 경우, A ([$Be_{Ga}$])와 $Be^*([Be_{Ga}-Ga_Sb}])$가 형성 ($A[Ga_{Sb}]+Be{\rightarrow}Be^*[Be_{Ga}-Ga_{Sb}]+[Be_{Ga}]$)됨을 보여 주는 중요한 결과인 것으로 분석된다. A, [Be], [$Be^*$] PL 피크 에너지는 각각 779, 787, 794 meV (오차범위 ${\pm}3\;meV$)이고, [$Be_{Ga}$]의 활성화 에너지는 ($23{\pm}3\;meV$) (20 K)임을 밝혔다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.459-467
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• 2019

The landing gear is a component that requires a high degree of safety to protect the lives of rotary-wing aircraft and boarding personnel, absorbing the impact on transfer/landing and supporting the fuselage during taxiing and mooring on the ground. In particular, the wheel landing gear supporting the aircraft fuselage absorbs most of the shock from the ground through the shock absorber and tires. This ensures the safety of the pilot on board the aircraft and satisfies the operational capability of the soldiers between missions. During the operation of a rotary-wing aircraft, a number of piston pins, which are a component of the right main wheel landing gear, were found to be broken. Therefore, this study examined the root cause of the piston pin crack phenomenon found in the main wheel landing gear. For this purpose, various causes were identified from fracture surface analysis of a flight test. In particular, the possibility of cracking was analyzed based on the influence on the fastening torque with the drag beam component applied to the piston pin at the time of development. This ensures the fatigue life and structural integrity.

• Nuclear Engineering and Technology
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• v.22 no.4
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• pp.337-350
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• 1990

A post-irradiation annealing study was conducted with use of reactor pressure vessel(RPV) steel A533B Cl.1 base metal irradiated to a dose of 4.84$\times$10$^{18}$ n/$\textrm{cm}^2$ at about 38$0^{\circ}C$. Microhardness and positron annihilation (PA) methods were used to obtain better understanding of the recovery of radiation hardening. Isochronal anneal experiments indicated that two recovery processes occur during annealing of irradiated specimens. The first recovery process occurs in the temperature range of 280-3O5$^{\circ}C$, Michrohardness and positron annihilation (PA) methods were used to obtain better understanding of the recovery of radiation hardening. Isochronal anneal experiments indicated that two recovery processes occur during annealing of irradiated specimens. The first recovery process occurrs in the temperature range of 280-305$^{\circ}C$. The variations of Ip, Iw and R parameters indicated that the formation of vacancy clusters by vacancy agglomeration and the annihilation of monovacancies are the first recovery process. The second recovery process occurs in the range of 405-49$0^{\circ}C$ and positron annihilation parameters measured indicated that the dissolution of carbon atoms decorated around vacancy-type defects and possible precipitates, and the annihilation of monovacancies give rise to the second recovery process. It was further indicated that radiation anneal hardening (RAH) in the range of 305-405$^{\circ}C$ between the temperature ranges for the two processes occurs due to the formation of carbon-decorated vacancy clusters and precipitates. The activation energies, orders of reaction and other characteristics of recovery processes were determined by the Meechan-Brinkman method. The activation energy for the first recovery process was determined as 1.76 eV and that for the second recovery process as 2.00eV. These values are lower than those obtained by other workers. This difference may be attributed to the lower copper content of the RPV steel used in the present study. The order of reaction for the first recovery process was determined as 1.78, while that for the second recovery process as 1.67 Non-integer orders of reaction for recovery processes seem to be attributed to the fact that several mechanisms for the first order and the second order of reaction are compounded in one process. This result also supports for the above conclusions from measurements of PA parameters.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.2
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• pp.105-113
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• 2015

The theory of landscape architecture applies environmental ethics in order to secure an ecological status. However, environmental ethics that focus on nature conservation excludes landscape architecture as artifacts. In the process, it is hard to identify what landscape architecture insists on as the middle position between humans and nature. Rather, landscape architecture pretends to be an 'agent of nature' and pushes the traditional moral values 'for people.' Therefore, the purpose of this study is to reestablish the anthropocentrism moral position of landscape architecture through critical analysis. Hargrove's weak anthropocentrism' of several environmental ethics branches accepts natural aesthetics(such as landscape architecture) as an ethical virtue. But environmental ethics makes landscape architecture a critical target. For that reason, this study looked into critical contents and objects that in a position to moral, aesthetic and landscape architecture. Critical details are as follows: First, nature is an absolute as an aesthetic and moral value, but landscape architecture is an imitation and takes a relaxed attitude about nature. Second, nature is full of aesthetic substance because it is self-creative, but landscape architecture is designed nature covered human flaws through imagination. Third, environmental management granting techniques in nature generate a moral nihilism. As an argument, environmental ethics overlooked the moral practices of landscape architecture beyond nature another moral aspect of creation and the imagination-and moral aspects of environmental management as 'care' because they rule out 'moral autonomy' and simplify what is considered 'good.' As a result, conservation cannot be the only virtue why the problem of nature in reality cannot be separated from human life. The moral position of landscape architecture based on a 'good life' is more appropriate under anthropocentrism than as a middle position.

• Journal of Korean Philosophical Society
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• v.129
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• pp.111-140
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• 2014

In this paper, the main subjects with which I deal are as follows: (1) Is Distancing Philosophy from the real ruling power a way of practical-philosophical resistance, based on social reformation as a axiological directivity of Kim Tae-Gil's ethical thought, though it is negative type of resistance? Or is it a sort of transformed value-free opportunist behavior which allows antidemocratic ruling group to coerce the people into submission, assuming an uncompromising stand seemingly? (2) Is Kim's defense argument on the opening of the course of National Ethics and the all-out activation of National Ethics education under Park's Yushin Regime derived from his own philosophical belief? Or is it brought out from the external conditions and circumstances surrounding Kim Tae-Gil which forces him to participate in the national undertaking for the settlement of the course of National Ethics in the university? The 'provisional' answers about the two subjects are as follows: (1) Kim's Distancing Philosophy is a type of practical philosophical revolt against the dictatorship power under Yushin Regime, though it is negative form of resistance. We can accept this philosophical elucidation above all by confirming the fact that the reform of reality is the main ethical trait running through his entire ethical thought system. However distancing philosophy disclose the crucial limits to allow itself to boil to the philosophical practice compromising with real ruling power eventually, though it is intended upon its own social ethical directivity and conviction. (2) The primary factor which affects Kim to propose such an advocation argument on the course of National Ethics and the education of National Ethics is the external conditions and circumstances surrounding him, especially the power-relation between he and ruling group and intimate human relation between he and his superior philosophers who carries out the role of a ideologue for the Yushin Regime, rather than his own philosophical belief. But no matter what primary factor, Kim's action to make a advocating argument to support the course and the education of National Ethics is to blame, on that account that he cannot adequately his social responsibility and role given to him as a reformist moral philosopher who will pursue the realization of righteous democratic society. Along with that, It is not too enough to criticize him sharply for such defending action. The reason is that his supporting stance for National Ethics education is brought out, by not adhering closely to the philosophical way of distancing from the dictatorial power devoid of political legitimacy and moral justification.

• The Korean Journal of Air & Space Law and Policy
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• v.31 no.2
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• pp.3-35
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• 2016

The United States Constitution gives power to the federal district courts to hear admiralty cases. 28 U.S.C. §.133, which states that "The district courts shall have original jurisdiction, exclusive of the Courts of the States, of any civil case of admiralty or maritime jurisdiction." However, the determination of whether a case is about admiralty or maritime so that triggers admiralty jurisdiction was not a simple question. Through numerous legal precedents, the courts have drawn a line to clarify the boundary of admiralty cases. This unique jurisdiction is not determined by the mere involvement of a vessel in the case or even by the occurrence of an event on a waterway. As a general rule, a case is within admiralty jurisdiction if it arises from an accident on the navigable waters of the United States (locus test) and involves some aspect of maritime commerce (nexus test). With regarding to the maritime nexus requirement, the US Supreme Court case, Executive Jet Aviation, Inc. v. City of Cleveland, held that federal courts lacked admiralty jurisdiction over an aviation tort claim where a plane during a flight wholly within the US crashed in Lake Erie. Although maritime locus was present, the Court excluded admiralty jurisdiction because the incident was "only fortuitously and incidentally connected to navigable waters" and bore "no relationship to traditional maritime activity." However, this historical case left a milestone question: whether an aircraft disaster occurred on navigable water triggers the admiralty jurisdiction, only for the reason that it was for international transportation? This article is to explore the meaning of admiralty jurisdiction over aviation accidents at US courts. Given that the aircraft engaged in transportation of passenger and goods as the vessels did in the past, the aviation has been linked closely with the traditional maritime activities. From this view, this article reviews a decision delivered by the Seventh Circuit regarding the aviation accident occurred on July 6, 2013 at San Francisco International Airport.

• Korean Journal of Biological Psychiatry
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• v.5 no.1
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• pp.34-45
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• 1998

We provide the reader with a brief introduction to the neurobiology of neuropeptides. Several comprehensive reviews of the distribution and neurochemical, neurophysiological, neuropharmacological and behavioral effects of the major neuropeptides have recently appeared. In reviews of the large number of neuropeptides in brain and their occurance in brain regions thought to be involved in the pathogenesis of major psychiatric disorders, investigators have sought to determine whether alternations in neuropeptide systems are associated with schizophrenia, mood disorders, anxiety disorders, alcoholism and neurodegenerative disease. There is no longer any doubt that neuropeptide-containing neurons are altered in several neuropsychiatric disorders. One of the factors that has hindered neuropeptide research to a considerable extent is the lack of pharmacological agents that specifically alter the synaptic availability of neuropeptides. With the exception of naloxone and naltrexone, the opiate-receptor antagonists, there are few available neuropeptide- receptor antagonists. Two independent classes of neuropeptide-receptor antagonists has been expected to be clinically useful. Naltrexone, a potent ${\mu}$-receptor antagonist, has been used successfully to reduce the need for alcohol consumption. And cholecycstokinin antagonists are now in development as a new class of anxiolytics, which would be expected to be free from tolerance and physical dependence and lack of sedation. In this review, we deal with these two kinds of neuropeptide system, the opioid system and cholesystokinins in the brain. The role of opioid systems in the reinforcement after alcohol consumtion and that of cholesystokinins in the pathogenesis of anxiety will be discussed briefly. As we know, the future for neuropeptides in psychiatry remains bright indeed.

• Journal of the Mineralogical Society of Korea
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• v.16 no.3
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• pp.201-213
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• 2003

The adsorption property and ability of domestic zeolites for some heavy metal ions (Ag, Pb, Cr, Cu, Zn, Mn), which may cause a serious environmental problem in industrial wastewater, were evaluated on ore unit through a series of adsorption experiments together with careful examinations of mineral composition and properties of the zeolites. Though the adsorption behavior basically took place in the form of a cation exchange reaction, the higher CEC value does not necessarily to imply the higher adsorption capacity for a specific heavy metal. A general trend of the adsorption selectivity for heavy metals in the zeolites is determined to be as follow: $Ag\geq$Pb>Cr,Cu$\geq$Zn>Mn, but the adsorption properties of heavy metal ions somewhat depend on the species and composition of zeolite. Clinoptilolite tends to adsorb selectively Cu in case of Cr and Cu, whereas heulandite prefers Cr to Cu. A dominant adsorption selectivity of the zeolite ores for Ag and Pb is generally conspicuous regardless of their zeolite species and composition. The zeolite ores exhibit a preferential adsorption especially for $Ag^{+}$ so as not to regenerate when treated with $Na^{+}$ . In the adsorption capacity for heavy meta ions, the zeolites differ in great depending on their species: ferrierite>clinoptilolite>heulandite. Considering the CEC value of mordenite, the mordenite-rich ore appears to be similar to the clinoptilolite ore in the adsorption capacity. The adsorption capacity for heavy metals is not positively proportional to the CEC values of the zeolites measured by the exchange reaction with ammonium ion. In addition, the adsorption capacity roughly tends to depend on the zeolite contents, i.e., the grade of zeolite ore, but the trend is not consistent at all in some ores. These may be caused by the adsorption selectivity for some specific heavy metals, the presence of possible stacking micro-faults and natural cations such as K hardly to exchange in the zeolite. Considering the economic availability and functional effectiveness as natural zeolite resources, clinoptilolite ores could be applicable to utilize the domestic zeolites for the removal of heavy metals.