Effect of diffusible hydrogen and weld metal microstructure on cold crack susceptibility of high strength weldment

Cheolho Park(박철호),Wanchuck woo(우완측),Namhyun Kang(강남현) 대한용접·접합학회 2019 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2019 No.11

Effect of prestrain on hydrogen diffusion and trapping in structural steel

Park, Cheolho,Kang, Namhyun,Kim, Myunghyun,Liu, Stephen Elsevier 2019 Materials letters Vol.235 No.-

<P><B>Abstract</B></P> <P>Hydrogen permeation tests were electrochemically performed to measure hydrogen diffusion and trapping in EH 36 steel. Permeation transients were measured through charging and decaying cycles, for specimens prestrained to varying degrees (0–20%). With increasing prestrain, the effective hydrogen diffusivity (<I>D<SUB>eff</SUB> </I>) decreased, while the total/reversible hydrogen content (<I>C<SUB>o</SUB> </I> and <I>C<SUB>r</SUB>, respectively</I>) increased. The immobile dislocation of the 20%-prestrained specimens decreased <I>D<SUB>eff</SUB> </I> by approximately ten times and increased <I>C<SUB>o</SUB> </I> and <I>C<SUB>r</SUB> </I> by approximately three times. The amount of irreversibly trapped hydrogen (<I>C<SUB>irr</SUB> </I>) remained approximately the same, regardless of the prestrain. The dislocations delay the motion of hydrogen and contain more reversible hydrogen.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen permeation tests successfully measured the hydrogen diffusivity and concentration. </LI> <LI> As the prestrain increased from 0 to 20%, the effective hydrogen diffusivity decreased. </LI> <LI> Total and reversible hydrogen concentrations increased with the prestrain. </LI> <LI> Irreversible hydrogen showed mostly the same value regardless of prestrain. </LI> <LI> The dislocations delay the motion of hydrogen and contain more reversible hydrogen. </LI> </UL> </P>

Effect of grain size on the resistance to hydrogen embrittlement of API 2W Grade 60 steels using in situ slow-strain-rate testing

Park, Cheolho,Kang, Namhyun,Liu, Stephen Elsevier 2017 Corrosion science Vol.128 No.-

<P><B>Abstract</B></P> <P>This study investigated the grain size effect on the resistance to hydrogen embrittlement (HE) of API 2W Grade 60 steels using in situ slow-strain-rate testing. Hydrogen was electrochemically charged into specimens and the hydrogen content evolved from diffusible hydrogen-trap sites was measured by thermal desorption spectrometry (TDS). The fine-grained (14μm) steel showed superior HE resistance despite exhibiting higher total hydrogen content than the coarse-grained (35μm) steel. Decreasing grain size resulted in a larger grain boundary area, thereby better reducing the normalized amount of diffusible hydrogen trapped per unit length of grain boundary.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen embrittlement resistance increased with grain size refinement. </LI> <LI> Quasi cleavage fracture decreased displacement significantly with increasing grain size. </LI> <LI> The amounts of hydrogen desorbed from lattice sites and grain boundaries increased with decreasing grain size. </LI> <LI> Fine-grained steel exhibited the lowest normalized hydrogen content in a unit grain boundary. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Microstructural Tuning of Si/TiFeSi₂ Nanocomposite as Lithium Storage Materials by Mechanical Deformation

Park, Hyeong-Il,Sohn, Myungbeom,Choi, Jeong-Hee,Park, Cheolho,Kim, Jae-Hun,Kim, Hansu Elsevier 2016 ELECTROCHIMICA ACTA Vol.210 No.-

<P><B>Abstract</B></P> <P>Melt-spun Si based alloy materials have gained much attention as high capacity anode materials for lithium-ion batteries because of their high capacity and relatively low production cost. However, their long-term cycle performance should be further improved for the commercial success. Herein, it is demonstrated that the electrochemical performances of Si/TiFeSi<SUB>2</SUB> active-inactive nanocomposite anode material could be further improved by the microstructural modification using its mechanical deformation. With the help of high-energy mechanical milling, the microstructural tuned Si/TiFeSi<SUB>2</SUB> nanocomposite material showed a reversible capacity of more than 1000mAhg<SUP>−1</SUP> with stable capacity retention up to 100 cycles. <I>Ex situ</I> X-ray diffraction analysis coupled with potentiostatic intermittent titration technique revealed that refining the sizes of the active Si and inactive TiFeSi<SUB>2</SUB> limited the lithiation of Si phase to Li<SUB>21</SUB>Si<SUB>8</SUB> and this suppressed lithiation led to less volume changes of the electrodes and the improvement of the mechanical integrity of Si/TiFeSi<SUB>2</SUB> nanocomposite material.</P>

Effect of Prestrain on Hydrogen Embrittlement Susceptibility of EH 36 Steels Using In Situ Slow‑Strain‑Rate Testing

Cheolho Park,Namhyun Kang,Stephen Liu,Juseung Lee,Eunjoon Chun,Sun‑Joon Yoo 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3

Hydrogen can provide pure and clean energy; however, to use it as an energy source, facilities such as hydrogen carriersand recharging stations need to be constructed. Structural steels are affected by hydrogen embrittlement (HE), and theirsusceptibility to this needs to be investigated prior to their use in construction. Most structural steels are normally fabricatedusing thermomechanical controlled processing, which produces a large dislocation density to increase strength. This studyinvestigated the prestrain effect on HE susceptibility of EH 36 steels using thermal desorption spectroscopy (TDS) andin situ slow-strain-rate testing. Hydrogen was electrochemically charged into specimens, and the reversible hydrogen contentand that relating to trap sites were measured using TDS. With an increase in prestrain, there was increase in the diffusiblehydrogen content; furthermore, with hydrogen charging, there was a drastic reduction in total elongation with an increasein prestrain. In addition, there was an increase in HE susceptibility with an increase in prestrain compared to when an aircondition was employed. Specifically, there was an abrupt increase in HE sensitivity at a prestrain value between 10 and15%; strain hardening was more dominant below a prestrain value of 10%; and HE was more dominant above a prestrainvalue of 15% for EH 36 steels.

Whole cigarette smoke condensates induce ferroptosis in human bronchial epithelial cells

Park, Eun-Jung,Park, Yoo-Jin,Lee, Sang Jin,Lee, Kyuhong,Yoon, Cheolho Elsevier 2019 Toxicology letters Vol.303 No.-

<P><B>Abstract</B></P> <P>Cigarette smoke is responsible for many fatal pulmonary diseases, however, the toxic mechanism is still unclear. In this study, we first confirmed that whole cigarette smoke condensates (WCSC) contain hydrophilic elements, lipophilic and gaseous components. Then, we treated BEAS-2B cells, a normal human bronchial epithelial cell line, at dosages of 0.25, 0.5, and 1% for 24 h and explored the toxic mechanism. Cell viability decreased in a dose-dependent manner, and fission and fusion of mitochondria, damage of endoplasmic reticulume (ER) structures, and formation of autophagosome-like vacuoles were found in cells treated with 1% WCSC. Mitochondrial and ER volumes, lysosomal fluorescence intensity, LDH release, and intracellular ROS levels notably decreased at the highest doses compared with the control, whereas intracellular calcium ion and NO levels were significantly elevated accompanying G2/M phase arrest. Expression of an iron-binding nuclear protein-related gene (pirin) was the most up-regulated in the WCSC-treated cells with enhanced expression of antioxidant-related genes, whereas expression of carbonic anhydrase IX gene, a marker of tumor hypoxia, was the most down-regulated. Additionally, levels of apoptosis (BAX, Apaf-1, and cleavage of caspase-3 and PARP), autophagy (p62 and LC3B-II), ER stress (PERK, IRE-1a, Bip, and CHOP), antioxidant (SOD-1 and SOD-2), and MAPkinase activation (p-ERK, p-p38, and p-JNK)-related proteins were clearly enhanced following exposure to WCSC, whereas expression of several mitochondrial dynamics-related proteins was reduced with dose. Interestingly, expression of ferritin protein (light chain) was dramatically enhanced near the ER along with that of p62 protein. More importantly, the hypoxia inducible factor-1 pathway and ferroptosis were proposed among the 20 terms in KEGG pathway analysis, and secretion of IL-6 and IL-8, which are involved in hypoxia-induced inflammation, were clearly elevated with dose. Taken together, we suggest that WCSC may induce ferroptosis in bronchial epithelial cells via ER stress and disturbed homeostasis in mitochondrial dynamics caused by induction of hypoxia conditions.</P>

고강도강의 수소 확산에 미치는 전위 밀도의 영향

박철호(Cheolho Park),강남현(Namhyun Kang) 대한용접·접합학회 2017 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2017 No.11

法定代理와 민법 제126조의 관계

박철호(Park, CheolHo) 한양법학회 2009 漢陽法學 Vol.25 No.-

The problem is that whether delegation of legal power only happened by a legal act is recognized as a foundation the right of agency to be permitted and especially, agency provided by law is recognized as a foundation the right of agency. The right problem is that whether it can be applied by the section 126 that the procuration of conjugal household and the subrogation of a guardian of a person without legal capacity are provided by the section 827 of Korean civil law. Case law has solved whether the representation agency provided by the section 126 of Korean civil law can be applied by using transaction security. Of course, it is true that court try to make right application of rigid rules through "lawful reason", but case law say that there are no reason to judge differently both agency provided by law and discretion agency by the section 126 of Korean civil law. In case of procuration of conjugal household, case law can have validity in effect. But, in case of a guardian of a person without legal capacity, it is not matched to the basic of representation agency that a person without legal capacity is imposed on his/her responsibility for guilty to recognize a foundation the right of agency for the completion of representation agency. And also that is not matched to the principle of self-determination and self-responsibility that is based on a basis validity of legal act. And more, a guardian of a person without legal capacity should accept that there are other requirements of decision rather than realization of the law of logic. Examine the regulation of a family council of Korean civil law, there are reasons that we should accept. In effect that is kind of a formal act and we should consider it has the lack of ability to control. Accordingly, in case of agency provided by law of a person without legal capacity, the problem that whether the expression of procuration should be rightful should not be applied and also case law should be interpreted in limited ways.

대리모계약에 대한 유효성 논란과 법리분석

박철호(Park, CheolHo) 한양법학회 2009 漢陽法學 Vol.28 No.-

Today the advancement of life scientific technique contributed it solves a sterility effectively. It does so, it is this possibility of the artificial pregnancy such as the Artificial Insemination, the in vitro fertilization-embryo transfer, the gamete intrafalopian transfer etc. The birth of the child who leads the surrogate mother became accomplished. But the surrogate mother contract appears and the problems which forecast it cannot entirely before are proposed, There is to surrogate mother contract, the surrogate mother and the client where becomes the mother legally changes. The problem of many law will be able to occur. Each nations are taking the position which differs each other in about permission and prohibition of surrogate mother system. However the surrogate mother occurs from all countries, the nation which permits a surrogate mother contract or the nation which forbids a surrogate mother contract. Our country is not legal provision to about the surrogate mother contract. It does to entrust in interpretation of civil law. The legal interpretation as a matter of surrogate mother contract violates in the 103 provision of civil law. And so, the multiple position as invalidity thought a surrogate mother contract. But forbidding a surrogate mother contract restricts the desire of race preservation. Also the surrogate mother contract is contracted majority actually. The illegal behavior is promoted is containing a problem consequently. This Article is composed 6 part. The first and last part are introduction and conclusion. The second part is a meaning and background of surrogate mother contract. The third part is a argument in about effect of surrogate mother contract. The forth part is a juridical relation of surrogate mother contract. The fifth part is a our country legislation trend in about surrogate mother contract.

원치 않은 출산소송에 관한 판례평석

박철호(Park, CheolHo) 한양법학회 2012 漢陽法學 Vol.23 No.1

Wrongful birth describes a cause of action or claim by parents of a deformed or defective child who allege that negligent advice as to the risk of genetic or birth defects or negligent treatment, or failure to abort a fetus, by the doctor deprived them of the choice of avoiding the child’s conception or of terminating the pregnancy. In these cases, parents of child with disability allege that because the defendant doctor breached the duty owed to the patient, they were denied the opportunity to make an informed decision. This claim lies on the basis that had it not been for the doctor’s negligence, the imperfect child would not have been born. In traditional medical malpractice lawsuits doctor’s negligence is the direct cause in the child’s disability, but in wrongful birth cases his/her negligence are the indirect causes of child birth. After this new type of lawsuit like wrongful birth action had been litigated in the United States in the 1930s many courts in Germany, France, UK including the United States have been recognized to recover to the parents for birth of child with disability. In contrast, in Korea, wrongful birth actions have been brought by parents alleging that the physician’s negligence of their child caused the injury in 1990s in many lower court and since that time these have been big issues legally and socially. While some lower courts have recognized in this new type cause of action, others have rejected it based on the difficulty in determining damages. On the other hand the Supreme Court of Korea has generally indicated negative attitude to the cause of wrongful birth action. However, Korean Supreme Court, for the first time as the highest Court, had decided to recover to parents of children with disabilities for the mental damages excepting for property damages in 2002. After this 2002 Supreme Court decision because there are only one judgment in Seoul Western District Court it can not be said that many wrongful birth actions will be brought sooner or later. But in a long-term perspective it can be said that this new type actions will be gradually increasing in Korea. It was apparent that Korean Courts still had a negative view to the cause of wrongful birth action. But because the Supreme Court’s 2002 decision agreeing to allow the parents of disabled child to recover damages for the mental anguish was said rather progressive, it may seems to be a positive outlook on this issue. Meanwhile many courts of Korea have determined whether it can allow the parents of disabled child to recover damages, basing on Article 14 of Maternal and Child Health Act, allowance standard of abortion. When the abortion of the disabled fetus only can be allowed depending on Article 14 of Maternal and Child Health Act, Courts allowed damages to the parents of children with disabilities. But this Article 14 has been designed to allow abortion because of the health of the parents and this is just standard to judge whether the maintenance of pregnancy is harmful to the health of the mother of fetus. Therefore, it is unreasonable that it should be decided to recover the damages to the parents in wrongful birth action whether or not to admit by the Article 14 of Maternal and Child Health Act. Thus, the court should change their views. So it should be decided to recover the damages to the parents in wrongful birth action because of the doctor’s negligence, the duty violation doctor’s explanation and the health of the fetus itself. In this paper, it was reviewed the Supreme Court’s 2002 decision, investigated about whether or not to admit demage recover in this type of action, and examined the compensation range.