• Journal of the Korean Ceramic Society
• /
• v.49 no.6
• /
• pp.637-641
• /
• 2012

Due to its high production cost and relatively high energy consumption during the Siemens process, poly-silicon makers have been continuously and eagerly sought another silicon route for decades. One candidate that consumes less energy and has a simpler acidic and metallurgical purification procedure is upgraded metallurgical-grade (UMG) silicon. Owing to its low purity, UMG silicon often requires special steps to minimize the impurity effects and to remove or segregate the metal atoms in the bulk and to remove interfacial defects such as precipitates and grain boundaries. A process often called the 'gettering process' is used with phosphorus diffusion in this experiment in an effort to improve the performance of silicon solar cells using UMG silicon. The phosphorous gettering processes were optimized and compared to the standard POCl process so as to increase the minority carrier lifetime(MCLT) with the duration time and temperature as variables. In order to analyze the metal impurity concentration and distribution, secondary ion mass spectroscopy (SIMS) was utilized before and after the phosphorous gettering process.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.22 no.1
• /
• pp.45-53
• /
• 1985

For the analysis of vertical vibrations of a ship's hull, the Timoshenko beam analogy is accepted up to seven or eight-node modes provided that the system parameters are properly calculated. As to the shear coefficient, it has been a common practice to apply the strain energy method or the projected area method. The theoretical objection to the former is that it ignores lateral contraction due to Poisson's ratio, and the latter is of extreme simplifications. Recently, Cowper's and Stephen's shear coefficient formulas have drawn ship vibration analysts' attentions because these formulas, derivation of which are based on an integrations of the equations of three-dimensional elasticity, take Poisson's ratio into account. Providing computer programs for calculation of the shear coefficient of ship sections modeled as thin-walked multicell sections by each of the forementioned methods, the authors calculated natural vibration characteristics of a bulk carrier and of a container ship by the transfer matrix method using shear coefficients obtained by each of the methods, and discussed the results in comparision. The major conclusions resulted from this investigation are as follows: (1) The shear coefficients taking account of the effects of Poisson's ratio, Cowper's $K_c$ and Stephen's $K_s$, result in higher values of about 10% in maximum as compared with the shear coefficient $K_o$ based on the conventional strain energy methods; (a) $K_c/K_o{\cong}1.05\;and\;K_s/K_o{\cong}1.10$ for ships having single skin side-shell such as a bulk carrier. (b) $K_c/K_o{\cong}1.02\;and\;K_s/K_o{\cong}1.05$ for ships having longitudinally through bulkheads and/or double side-shells in the portion of the cargo hod such as a container carrier. (2) The distributions of the effective shear area along the ship's hull based on each of $K_o,\;K_c\;and\;K_s$ are similar each another except the both end portions. (3) Natural frequencies and mode shapes of the hull based on each of $K_c\;and\;K_s$ are of small differences as compared each other. (4) In cases of using $K_c\;or\;K_s$ in ship vibration analysis, it is also desirable to have the bending rigidity be corrected according to the effective breadth concept. And then, natural frequencies and mode shapes calculated with the bending rigidity corrected in the above and with each of $K_o,\;K_c\;and\;K_s$ result in small differences as compared each another. (5) Referring to those mentioned in the above (3) and (4) and to the full-scale experimental results reported by Asmussen et al.[17], and considering laboursome to prepare the computer input data, the following suggestions can safely be made; (a) Use of $K_o$ in ship vibration analysis is appropriate in practical senses. (b) Use of $K_c$ is appropriate even for detailed vibration analysis of a ship's hull. (6) The effective shear area based on the projected area method is acceptable for the two-node mode.

• The Korean Journal of Air & Space Law and Policy
• /
• v.7
• /
• pp.101-134
• /
• 1995

Article 3 Paragraph 1 of the Warsaw Convention regulates the requirements of passenger tickets, Article 4 Paragraph 3, the requirements of baggage tickets, Article 8, the requirements of airway bills. In this article the writer has discussed the legal nature of the documents of air carriage, such as air waybills, passenger tickets and baggage checks. Further, the writer has also discussed several issues relating to the use of the documents of air carriage under the Warsaw Convention. Article 3 Paragraph 2, as well as Article 4 Paragraph 4 and 9 provides that the carrier shall not be entitled to avail himself of the provisions of the Convention which evade or limit his liability. In particular, the Montreal Agreement of 1966 provides that the notification on the carrier's liability in passenger ticket should be printed in more than 10 point type size with contrasting ink colors. However, another question is whether the carrier shall not be entitled to avail himself of the liability limit under the Convention in case the type size is below 10 points. The Convention does not specify the type size of certain parts in passenger tickets and only provides that the carrier shall not be entitled to avail himself of liability limit, when a carrier fails to deliver the ticket to passenger. However, since the delivery of passenger tickets is to provide an opportunity for passengers to recognize the liability limit under the Convention and to map out a subsequent measures, the carrier who fails to give this opportunity shall not be entitled to avail himself of the liability limit under the Convention. But some decisions argue that when the notice on the carrier's liability limit is presented in a fine print in a hardly noticeable place, the carrier shall not be entitled to avail himself under the Convention. Meanwhile, most decisions declare that regardless of the type size, the carrier is entitled to avail himself of liability limit of the provisions of the Convention. The reason is that neither the Warsaw Convention nor the Montreal Agreement stipulate that the carrier is deprived from the right to avail himself of liability limit of the provisions of the Convention when violating the notice requirement. In particular, the main objective of the Montreal Agreement is not on the notice of liability limit but on the increase of it. The latest decisons also maintain the same view. This issue seems to have beeen settled on the occasion of Elisa Chan, et al. vs. Korean Airlines Ltd. The U.S. Supreme Court held that the type size of passenger ticket can not be a target of controversy since it is not required by law, after a cautious interpretation of the Warsaw Convention and the Montreal Agreement highlighting the fact that no grounds for that are found both in the Warsaw Convention and the Montreal Agreement. Now the issue of type size can hardly become any grounds for the carrier not to exclude himself from the liability limit. In this regard, any challenge to raise issue on type size seems to be defeated. The same issue can be raised in both airway bills and baggage tickets. But this argument can be raised only to the tranportation where the original Convention is applied. This creates no problem under the Convention revised by the Hague Protocol, because the Hague Protocol does not require any information on weight, bulk, size, and number of cargo or baggage. The problem here is whether the carrier is entitled to avail himself of the liability limit of the provisions of the Convention when no information on number or weight of the consigned packages is available in accordance with Article 4 of the Convention. Currently the majority of decisions show positive stance on this. The carrier is entitled to avail himself of the liability limit of the provisions of the Convention when the requirement of information on number and weight of consigned packages is skipped, because these requirements are too technical and insubstancial. However some decisions declare just the opposite. They hold that the provisions of the Convention Article 4 is clear, and their meaning and effect should be imposed on it literally and that it is neither unjust nor too technical for a carrier to meet the minimum requirement prescribed in the Convention. Up to now, no decisions by the U.S. Supreme Court on this issue is available.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.04b
• /
• pp.7-7
• /
• 2009

Lead telluride (PbTe) is a very promising thermoelectric material due to its narrow band gap (0.31 eV at 300 K), face-centered cubic structure and large average excitonic Bohr radius (46 nm) allowing for strong quantum confinement within a large range of size. In this work, we present the thermoelectric properties of individual single-crystalline PbTe nanowires grown by a vapor transport method. A combination of electron beam lithography and a lift-off process was utilized to fabricate inner micron-scaled Cr (5 nm)/Au (130 nm) electrodes of Rn (resistance of a near electrode), Rf (resistance of a far electrode) and a microheater connecting a PbTe nanowire on the grid of points. A plasma etching system was used to remove an oxide layer from the outer surface of the nanowires before the deposition of inner electrodes. The carrier concentration of the nanowire was estimated to be as high as $3.5{\times}10^{19}\;cm^{-3}$. The Seebeck coefficient of an individual PbTe nanowire with a radius of 68 nm was measured to be $S=-72{\mu}V/K$ at room temperature, which is about three times that of bulk PbTe at the same carrier concentration. Our results suggest that PbTe nanowires can be used for high-efficiency thermoelectric devices.

• Analytical Science and Technology
• /
• v.5 no.2
• /
• pp.223-228
• /
• 1992

$Bi_2Sr_2Ca_2Cu_3Oy$-based superconductor phases were synthesized by the wet process using acetate precursors. Superconducting transition temperature ($T_c$) was determined from both measurements of electrical resistivity and magnetic susceptibility for the samples which were sintered at the temperatures of $850^{\circ}C$, $860^{\circ}C$, and $870^{\circ}C$ for 40 hours, respectively. The values of carrier concentration from Hall measurements were compared with $T_c$ data as a function of the sintering temperature. The formation mechanism of the superconducting phase was tentatively discussed on a basis of the distribution profile concept of the carrier concentration and the amount of superconducting phases in a ceramic bulk. This explanation may be supported by the experimental results of correlation between the relative amount of superconducting phases and the difference of $T_c$ values between superconducting onset temperature and cutoff temperature at each sintering temperature.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.4
• /
• pp.188-191
• /
• 2012

This paper introduces a new method regarding deuterium incorporation in the gate dielectric including deuterium implantation and post-annealing at the back-end-of-the process line. The control device and the deuterium furnace-annealed device were also prepared for comparison with the implanted device. It was observed that deuterium implantation at a light dose of $1{\times}10^{12}-1{\times}10^{14}/cm^2$ at 30 keV reduced hot-carrier injection (HCI) degradation and negative bias temperature instability (NBTI) within our device structure due to the reduction in oxide charge and interface trap. Deuterium implantation provides a possible solution to enhance the bulk and interface reliabilities of the gate oxide under the electrical stress.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2009.04a
• /
• pp.335-338
• /
• 2009

일반적으로 비중이 큰 철광석이나 석탄 등을 운반하는 선박화물선의 호퍼 너클 이음부는 여러 판이 용접되어 복잡한 형상을 가지고 있어 응력이 집중되어지므로 피로강도평가 시 많은 문제점이 노출되는 구간이다. 이번 연구에서는 기존 sloping 방식의 호퍼 너클 이음 부를 갖는 180k 산적화물선 표준 모델과 제안 되어진 round 방식의 호퍼 너클 이음 부를 갖는 산적화물선에 대하여 구조강도평가와 피로강도평가를 수행하였다. 이때 합리적인 비교를 위하여 제안되어진 모델은 기존의 표준 모델의 화물창과 발라스트창의용적이 일치하도록 제안하였다. 또한 CSR을 기반으로 한 하중들에 대하여 허용응력과 25년 피로수명을 만족하도록 구조부재를 결정하였으며 피로강도평가 결과를 바탕으로 호퍼 너클부의 변화에 따른 선각 중량과 상대 건조 비 개념을 이용하여 보다 효율적인 구조를 제시 하였다.

• Journal of the Society of Naval Architects of Korea
• /
• v.40 no.4
• /
• pp.53-58
• /
• 2003

Design of the corrugated watertight bulkhead for a bulk carrier is principally determined by the permissible limit of Classification requirements. As the weight of upper and lower stool has considerable portion of the total weight of the transverse bulkhead, optimum design including the stool geometry and size will play an important role on economic shipbuilding. The purpose of this study is focused on the minimization of steel weight using the design variables, which are the shape and the size of the corrugation as well as the upper and lower stools. Discrete variables are used as design variables for the practical design. In this study, the evolution strategies (ES), which can highly improve the possibility of leaching the global minimum point, are selected as an optimization method. Usefulness of this study is verified by comparison with the proven type ship design. As objective function, total weight of the transverse bulkhead including the upper and lower stools is used.

• Journal of the Korean Electrochemical Society
• /
• v.23 no.1
• /
• pp.18-23
• /
• 2020

Antimony telluride (Sb_xTe_y) thin films were synthesized by an electrodeposition method with a control of applied potential at room temperature. Characterization of electrical and thermoelectric properties such as conductivity, Seebeck coefficient, and power factor (P.F.) were conducted as a function of the chemical composition of the electrodeposited films. Morphology of thin films were dense and uniform and the composition was tailored from 25 to 60 at.% of the Sb content by altering the applied potential from -0.13 to -0.27 V (vs. SCE). The conductivity of the films were ranged from 2 × 10^-4 ~ 5 × 10^-1 S/cm indicating their amorphous behavior. The meaured Seebeck coefficient of films were relatively high compared to that of bulk single cyrstal Sb_xTe_y due to their low carrier concentration. The variation of the Seebeck coefficient of the films was also related to the change of chemical composition, showing the power factor of ~10 ㎼/mK².

• Biomedical Science Letters
• /
• v.11 no.1
• /
• pp.85-88
• /
• 2005

Hemoglobin is oxygen carrier protein within erythrocyte in blood. Apoprotein of this, globin, is synthesized in the cytosol but it's cofactor, heme, is synthesized in the mitochondria. It has not been known very well how globin receives the heme from mitochondria and folds to hemoglobin. In this folding process, the initial structure of globin seems to be very important. A small volume of globin at acid pH was added rapidly into the bulk of an egg phosphatidylcholine $60\%$ liposome, containing hemins, at neutral pH according to the Rapid Dilution method. It was observed that an acid-induced unfolding structure of globin is initially needed to receive hemins from the lipid bilayer of liposomes. Also, this conclusion was confirmed with the absorption spectrum of the refolded globin separated by centrifugation.