• Journal of Welding and Joining
• /
• 제17권5호
• /
• pp.83-88
• /
• 1999

In this paper resistance projection weldability of Zn coated steels with post treatment has been discussed. Projection welding was performed by a condenser discharge type power source which was equipped with welding parameter monitoring system. Mechanical test results indicated that the effect of post coatings on the projection front changed showing very small very small spattering at the weld strength was negligible. However, contamination rate of the block electrode varied depending on the post treatment coatings. Test results also showed that projection height before welding should be kept to be 80-100% of the specimen thickness as far as the surface quality was taken into consideration. Based on the high speed photography, discharge condition at the beginning stage of the welding process. It was considered that the spattering reduced the weld strength slightly at the optimum heat input range.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
• /
• pp.368-371
• /
• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Aerobic bioremediation has been highly effective in the remediation of many fuel releases, but Many aromatic hydrocarbons degrade very slowly under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen and denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. This study show that biodegradation of BTEX and MTBE is enhanced by the nitrate-amended microcosms under aerobic/anaerobic conditons. Although aromatic hydrocarbons degrade very slowly under anaerobic conditions. Biodegradaton was observed for all of the test compounds.

• 한국식품위생안전성학회지
• /
• 제8권2호
• /
• pp.13-21
• /
• 1993

Vibrio septicemia,, resulting in high mortality, has been caused by Vibrio vulnificus. Ingestion of marine products or contact with sea water contaminated with Vibrio vulnificus can cause septicemia. Vibrio vulnificus has been detected world wide and west sea area of Korea, Kum river estuary in particular, showed high detection rate. Higher detection rate of Vibrio vulnificus were reported in the bottom deposit with low depth of water, low salinity, and high COD. Man with the liver disease can easily come down with Vibrio septicemia and the main source is the sliced raw fish dish. The preventive measure for this disease is to wash raw fish material thoroughly with tap water and handle in sanitary conditions. Washing with sea water is strictly prohibited . It may be necessary to forbid the small-scale businessmen from selling the sliced ray fish dish in the vicinity of seashore. Man with the liver disease of diabetes should not swim or consume the raw fish dish in the contaminated area during summer.

• 대한안전경영과학회지
• /
• 제18권3호
• /
• pp.81-89
• /
• 2016

Floor slipperiness is a leading cause in slip and fall accidents which are a major source of occupational injuries in Korea. Researchers have estimated the slip and fall related accidents rank number one or two in number of the injured. The objectives of this study were to find the field contamination effect and improvement countermeasure. Slipping and falling are common accidents in large public facilities, especially facility which vulnerable adults generally use as like hospital. So, we measured the coefficient of friction of several floors on the floor in hospital, under dry and wet using BOT-3000. The results of the coefficient of friction measurements showed that floor type and surface conditions were all significant factors affecting the coefficient of friction. The most surprising finding of this study was that there were significant friction improvement when the floors were properly cleaned with cleaning equipments.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.1504-1507
• /
• 2009

In this paper, the etching behavior of ZnO in $CF_4$ plasma mixed Ar was investigated. Previously, the etch rate in $CF_4$/Ar plasma was reported that it is slower than that in Cl containing plasma. But, plasma included Cl atom can produce the by-product such as $ZnCl_2$. In order to solve this film contamination, no Cl containing etching gas is required. We controlled the etching parameter such as source power, substrate bias power, and $CF_4$/Ar gas ratio to acquire the fast etch rate using a ICP etcher. We accomplished the etching rate of 144.85 nm/min with the substrate bias power of 200W. As the energetic fluorine atoms were bonded with Zinc atoms, the fluoride zinc crystal ($ZnF_2$) was observed by X-ray photoelectron spectroscopy (XPS).

• 보존과학연구
• /
• 통권28호
• /
• pp.75-90
• /
• 2007

The ancient biomolecular remains are the potential source for paleobiology and paleoanthropology. Especially, ancient human specimens such as bone, teeth, and hair are powerful materials to identify historical origin and migration of ancestor population from the past. However, most excavated human specimens in archaeological sites have commonly problems as natural damage and exogenous contamination. We carried out histological and molecular analyses of excavated bone from the historic sites in South Korea from the recently discovered in tumulus of Seochun and Naju. Biological deterioration of bone was observed anatomically by optical and scanning electron microscope (SEM). We extracted degraded DNA, and amplified hyper variable region (HVR) of mitochondrial DNA (mtDNA) and amelogenin of nucleus DNA. This study applied and examined the relationships between histological preservation and DNA survival in excavated bone.

• 한국전기전자재료학회논문지
• /
• 제11권4호
• /
• pp.261-266
• /
• 1998

In developing the high density memory device, the etching of fine pattern is becoming increasingly important. Therefore, definition of ultra fine line and space pattern and minimization of damage and contamination are essential process. Also, the high density plasma in low operating pressure is necessary. The candidates of high density plasma sources are electron cyclotron resonance plasma, helicon wave plasma, helical resonator, and inductively coupled plasma. In this study, planar type magnetized inductively coupled plasma etcher has been built. The density and temperature of Ar plasma are measured as a function of rf power, flow rate, external magnetic field, and pressure. The oxide etch rate and selectivity to polysilicon are measured as the above mentioned conditions and self-bias voltage.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권2호
• /
• pp.79-82
• /
• 2004

The RF inductive discharge or inductively coupled plasma (ICP) continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technicology. Although most practical ICP operate at 13.56 [MHz]and 2.65 [MHz], the trend to reduce the operating frequency is clearly recognizable from recent ICP developments. In an electrodeless fluorescent lamp, the use of a lower operating frequency simplifies and reduces cost of rf matching systems and rf generators and can eliminate capacitive coupling between the inductor coil and plasma, which could be a strong factor in wall erosion and plasma contamination. In this study, the configuration of ferrite and fixture which operates at the frequency of 2.65[MHz]was discussed as functions of the ferrite thickness and distance by using the electromagnetic simulation software (Maxwell 2D).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
• /
• pp.244-245
• /
• 2007

The RF inductive discharge of inductively couples plasma (ICP) continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technology. Although most practical ICPs operate at 13.56 [MHz] and 2.65 [MHz], the trend to reduce the operating frequency is clearly recognizable from recent ICP developments. in and electrodeless fluorescent lamp, the use of a lower operating frequency simplifies and reduces cost of RF matching systems and RF generators and can eliminate capacitive coupling between the inductor coil and plasma, which could be a strong factor in wall erosion and plasma contamination. In this study, electric and optical characteristics of electrodeless fluorescent lamp by changing ferrite position is discussed.

• 상하수도학회지
• /
• 제31권3호
• /
• pp.219-228
• /
• 2017

Burial sites are constructed for the purpose of controlling air-born livestock diseases such as avian influenza and foot-and-mouth outbreak. As most of the burial sites are located in the agricultural land use, public concerns are mounting about soil and groundwater contamination. During precipitation events, contaminated baseflows are released from the burial sites into surface waters. Baseflow are therefore required to be managed properly, by monitoring and even by remediation means. We propose each burial sites should be regarded as a point source possibly degrade groundwater, thus be managed in watershed scale for the purpose of surface water quality conservation.