• Journal of Advanced Marine Engineering and Technology
• /
• 제13권4호
• /
• pp.54-62
• /
• 1989

When some kinds of inhibitors, i.e. $1{\times}10{-3}mol/l$ arsenic trioxide, 0.2 mol/l 2-mercaptoethanol, 0.2mol/l thiourea were added to 3% NaCl solution, there were some considererable effects to decrease corrosion current density in natural potential condition and the effect fo solution temperature increasing corrosion rate was smaller than that of no addition to 3% NaCl solution. However the susceptibility of hydrogen embrittlement due to over-protection in case of cathodic protection was much greater than that of no addition, especially was the greatest in case of addition of 2-mercaptoethanol. Therefore adding inhibitors for anti-corrosion effect, it is suggested that selection of the optimum protection potential is important from the view point of prevention against hydrogen embrittlement due to over-protection in case of cathodic protection.

• Corrosion Science and Technology
• /
• 제11권6호
• /
• pp.242-246
• /
• 2012

This measurement represents the effectiveness of sacrificial anode cathodic protection (SACP) system in a coastal bridge structure. To verify the cathodic protection (CP) effect, the monitoring sensor (DMS-100) that could measure potential, corrosion rate, current, concrete resistivity, and temperature was embedded. The measurement conducted for three years after CP system was installed. Specifically, due to the fact that fresh water and sea water was repeated in the bridge structure, this bridge structure presented special CP behavior. Measurement factors were CP potential, CP current, concrete resistivity, and depolarization potential. In addition, visual inspection was also carried out. As a result of current and depolarization measurement, CP system was well activated in most piers.

• Journal of Advanced Marine Engineering and Technology
• /
• 제30권1호
• /
• pp.157-168
• /
• 2006

Recently, interest in using Al alloys in ship construction instead of fiber-reinforced plastic (FRP) has increased because of the advantages of A) alloy ships over FRP ships, including high speed, increased load capacity. and ease of recycling. This paper investigated the mechanical and electrochemical properties of Al alloys in a slow strain rate test under various potential conditions. These results will provide reference data for ship design by determining the optimum protection potential regarding hydrogen embrittlement and stress corrosion cracking. In general, Al and Al alloys do not corrode on formation of a film that has resistance to corrosion in neutral solutions. In seawater, however, $Cl^-$ ions lead to the formation and destruction of a Passive film. In a potentiostatic experiment. the current density after 1200 sec in the Potential range of $-0.68\~-1.5\;V$ was low. This low current density indicates the protection potential range. Elongation at an applied potential of 0 V was high in this SSRT. However, corrosion protection under these conditions is impossible because the mechanical properties are worse owing to decreased strength resulting from the active dissolution reaction in parallel parts of the specimen. A film composed of $CaCO_3\;and\;Mg(OH)_2$ confers corrosion resistance. However, at potentials below -1.6 V forms non-uniform electrodeposition coating, since there is too little time to form a coating. Therefore, we concluded that the mechanical properties are poor because the effect of hydrogen gas generation exceeds that of electrodeposition. Comparison of the maximum tensile strength, elongation, and time to fracture indicated that the optimum protection potential range was from -1.45 to -0.9 V (SSCE).

• Journal of Welding and Joining
• /
• 제19권2호
• /
• pp.182-190
• /
• 2001

A marine structural material was well known to have high tensile strength, good weldability and proper corrosion resistance. Cu-containing high strength low alloy(HSLA) steel was recently developed for their purposes mentioned above. And the steel is free about preheating for welding, therefore it is reported that shipbuilding cost by using it can be saved more or less. However the marine structural materials like Cu-containing HSLA steel are being generally adopted with cathodic protection method in severe corrosive environment like natural sea water but the high strength steel may give rise to Hydrogen Embrittlement due to over protection at high cathodic current density for cathodic protection. In this study Cu-containing HSLA steel using well for marine atructure was investigated about the susceptibility of Hydrogen Embrittlement as functions of tensile strength, strain ratio, fracture time, and fracture mode, etc. and an optimum cathodic protection potential by slow strain rate test(SSRT) method as well as corrosion properties in natural sea water. And its corrosion resistance was superior to SS400 steel, but Hydrogen Embrittlement susceptibility of Cu-containing HSLA steel was higer than that of SS400 steel. However Hydrogen Embrittlement of its steel by SSRT method was showed with pheonomena such as decreasing of fracture time, strain ratio and fracture mode of QC(quasi-cleavage). Eventually it is suggested that an optimum cathodic protection potential not presenting Hydrogen Embrittlement of Cu-containing of HSLA steel by SSRT method was from-770mv(SCE) to - 900mV(SCE)under natural sea water.

• 디지털융복합연구
• /
• 제12권5호
• /
• pp.325-334
• /
• 2014

본 연구는 보건행정 전공 대학생들의 개인정보보호에 대한 인지 수준을 파악하여 개인정보보호에 대한 올바른 인지 및 실천이 이루어질 수 있는 방안 모색에 도움을 주고자 실시되었다. 조사방법은 보건행정 전공 대학생 687명을 대상으로 2012년 12월 3일부터 2013년 6월 21일까지 설문조사를 실시하였다. 연구결과, 개인정보보호법에 대한 인지는 17.2%로 낮은 수준을 나타냈다. 개인정보보호영역에 대한 인식도와 실천도는 개인정보보호법에 대한 인지가 있는 경우 모든 영역에서 유의하게 높은 수준으로 나타났으며, 인식도가 높을수록 실천도가 높게 나타나는 정의 상관관계로 나타났다. 개인인식정보 항목에 대한 인지율은 57.0%, 관리되어야 할 개인정보에 대한 인지율은 53.7%로 중간정도 수준으로 분석되었다. 따라서 보건행정 전공 대학생들에게 개인정보보호법에 대한 인지도를 높이기 위하여 개인정보보호법을 주지시킬 수 있는 교육 시간 및 교과목 편성을 통해 개인정보보호에 대한 올바른 인지 및 실천이 이루어지도록 하여야 할 것이다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
• /
• pp.11-14
• /
• 2004

Digital Video Broadcasting - Satellite (DVB-S) [1] (EN 300 421(bibliography)) was introduced as a standard in 1994. However, by combing with higher order modulation, promise more powerful alternatives to the DVB-S / DVB-DSNG coding and modulation schemes. Variable rate coding and modulation (VCM) may employed to provide different levels of error protection to different service components. Adaptive coding and modulation (ACM) provides more exact channel protection and dynamic link adaptation to propagation conditions, targeting each individual receiving terminal. By these reasons, DVB-S2 introduced. This paper derives exact symbol error rate(SER) of 16-Amplitude Phase Shift Keying(APSK) modulation by using Craig's formula. 16-APSK modulation is used in DVB-S2. The difference between Union Bound and Craig's formula is 1.26dB in low SNR and 0.1dB in high SNR.

• Journal of Radiation Protection and Research
• /
• 제5권1호
• /
• pp.1-6
• /
• 1980

A portable count-ratemeter and a thermoluminescent detector ($CaSO_4:Dy$) have been used to obtain total gamma dose rates at approximately 50 locations during the course of several survey trips in the southeastern Korea. The purposes of these measurement were to provide a future reference data and to establish the approximate range of population exposure to the natural environmental radiation. The natural levels encountered ranged from a low of 14.6 microroentgen per hour to a high of 18.9 microroentgen per hour with a mean of $16.3{\pm}1.0$ microroentgen per hour. Among these results are the relatively high natural dose rate levels in the Masan area and Yangsan-Tongdosa area with the relatively low natural dose rate levels in the Gyeongsan-Cheongdo area and the Samrangjin-Jinyeong-Gimhae area.

• 한국염색가공학회지
• /
• 제13권6호
• /
• pp.359-366
• /
• 2001

In this study, wool, silk and cotton fabrics were dyed with natural dyes derived from Ginkgo biloba bark using various mordants, and their dyeabilities were discussed. Additionally the fastness to washing, perspiration, light, rubbing, and drycleaning were investigated. And the effects of bacteria reduction and UV-B protection rate were also checked. The optimum dyeing condition of the colorants extracted from the Ginkgo biloba bark was three repeated dyeing at$95^\circ{C}$ for 1 hr. by using post mordanting. Mordanting improved the fastness to washing, Perspiration and drycleaning, but the fastness to light and rubbing were not increased. The bacteria reduction rate of the wool fabric increased drastically by dyeing with extract of Ginkgo biloba bark and its effect maintained after repeated washing and drycleaning. UV-B protection rate of the natural fibers increased by dyeing with extract of Ginkgo biloba bark and the dyed wool fabric was the best of the three fabrics.

• 한국염색가공학회지
• /
• 제13권6호
• /
• pp.1-1
• /
• 2001

In this study, wool, silk and cotton fabrics were dyed with natural dyes derived from Ginkgo biloba bark using various mordants, and their dyeabilities were discussed. Additionally the fastness to washing, perspiration, light, rubbing, and drycleaning were investigated. And the effects of bacteria reduction and UV-B protection rate were also checked. The optimum dyeing condition of the colorants extracted from the Ginkgo biloba bark was three repeated dyeing at 95℃ for 1 hr. by using post mordanting. Mordanting improved the fastness to washing, Perspiration and drycleaning, but the fastness to light and rubbing were not increased. The bacteria reduction rate of the wool fabric increased drastically by dyeing with extract of Ginkgo biloba bark and its effect maintained after repeated washing and drycleaning. UV-B protection rate of the natural fibers increased by dyeing with extract of Ginkgo biloba bark and the dyed wool fabric was the best of the three fabrics.

• 대한가정학회지
• /
• 제38권11호
• /
• pp.63-75
• /
• 2000

To identify the actual situation of financial information disclosure, a content analysis was performed on pamphlets of a time deposit and a new reserve trust offered by banks and other financial institutes. Although consumers required information on interest rate, tax favor, loan service, protection of brink depositors and bank security to select a financial service account, informations offered on pamphlets are not sufficient. Therefore concrete way of information offer system shoed be developed. In offering interest rate, interest rate after tax deduction or payment at maturity should be also mentioned. Information on tax favor, protection of bank depositors and bank security should be contained in pamphlets as well. Use of easy terms and notes are recommended for developing pamphlets for financial products.