• 한국생산제조학회지
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• 제8권4호
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• pp.45-51
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• 1999

In this study to assess chip breaking characteristics of cold-drawn free machining steels a newly developed non-dimensional parameter chip breaking index CB has been adopted. And for comparison with free machining steels chip breaking characteristics of conventional carbon steels were investigated. Properly controlled chips were produced with the CB value of 0.05-0.2 regardless of steel types. In case of cold-drawn free machining steels however cycle times of chip breaking are relatively shorter than those of conventional steels. And properly controlled chips were obtained from wider range of feed rate.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.21-26
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• 1999

In this study, to assess chip breaking characteristics of cold-drawn free machining steels, a newly developed non-dimensional parameter, chip breaking index, C/sub B/ has been adopted. And for comparison with free machining steels, chip breaking characteristics of conventional carbon steels were investigated. Properly controlled chips were produced with the C/sub B/ value of 0.05∼0.2, regardless of steel types. In case of cold-drawn free machining steels, however, cycle times of chip breaking are relatively shorter than those of conventional steels. And properly controlled chips were obtained from wider range of feed rate.

• 한국기계가공학회지
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• 제4권2호
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• pp.3-9
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• 2005

In this study, the chip breaking characteristics of S, PbS and BiS free machining steels have been assessed. PbS free machining steel shows the lowest value of chip thickness ($t_c$) under the same cutting conditions. SM10C steel has the largest value of the chip cross-section area ratio ($R_{CA}$). As the feed rate becomes larger the chip breaking cycle time ($T_B$) decreases and the chip breaking index ($C_B$) increases. The properly controlled-C type chip has been obtained with the value of $C_B$ between 0.05 and 0.2. Free machining steel, PbS produces the properly controlled-C type chip in a wider feed rate range than other steels.

• 한국정밀공학회지
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• 제11권6호
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• pp.179-184
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• 1994

In this study a nondimensional parameter, feed/land length(F/L) was introduced, and using this parameter, cutting performance and chip breaking characteristics of the groove and the land angle type chip formers were assessed. Specific cutting energy consumed and shape of broken chip with its breaking cycle time were appraised to find out the ranges of F/L value where efficient cutting and effective chip breaking could be achieved. C type chip was found out to be the most preferable in terms of cutting efficiency.

• 한국산업융합학회 논문집
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• 제2권2호
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• pp.181-186
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• 1999

For an unmanned machining system, the control and disposal of chips is one of the most serious problems at present. In order to perform chip control, feed/land length($F_L$) was introduced, and using this parameter, the cutting performance and chip breaking characteristics of groove-type and the land -angle-type chip formers were assessed. The specific cutting energy consumed and the shape of broken chips with its breaking cycle time were evaluated to find out the ranges of $F_L$ value where efficient cutting and effective chip breaking could be achieved. The C type chip was found to be the most preferable from the view point of cutting efficiency.

• 대한토목학회논문집
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• 제31권4A호
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• pp.303-309
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• 2011

적층고무받침은 지진격리 교량에서 면진장치로 주로 사용되고 있으며, 지진격리 설계시 적층고무받침의 성능 및 거동특성을 파악하는 것은 매우 중요하다. 적층고무받침의 주요 평가요소로는 압축 및 전단특성 그리고 인장특성으로 구분된다. 이 요소 중 압축특성 및 전단특성에 대한 특성실험 결과는 많으나, 인장특성에 대한 자료는 충분하지 않다. 이에 따라 본 연구에서는 인장하중을 받는 적층형 고무받침의 특성에 대해 연구를 수행하였다. 적층고무받침의 인장시험은 형상계수 및 전단변형 변화에 따른 기계적 특성에 대하여 검토하였다. 실험결과 인장변형이 증가 할수록 인장이력곡선은 비선형 특성을 보이며, 단순인장시험결과 300%이상 인장변형 후 파괴되었다. 반면에 전단변형된 상태에서 인장파괴는 약 40%이상의 인장변형 후 파괴되었다. 또한 형상계수가 낮을수록 극한인장 파괴성능이 저하되었다. 이와 같은 결과는 명확하지는 않지만 고무 층이 3축 인장 받을 경우 내부공극에 의해 균열이 확장되어 파괴가 발생하는 것으로 추측된다. 본 연구결과는 지진격리 구조물 설계시 인장하중에 대한 기초자료로 충분히 활용 가능할 것으로 판단된다.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.1076-1082
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• 2005

Breaking from the past convention, most construction firms are lotting out their apartments with their own brand names. They don't have, however, differentiated marketing strategies based on unique brand awareness. Rather, virtual absence of marketing strategies has brought about unfiltered introduction of architectural elements of the competition and excessive advertising efforts. Consequently confusion is at hand for consumers' purchase decision since they are not aware of the differences between the apartments. The purpose of this study is to make consumers have clear brand awareness by presenting appropriate brand strategies based on sound marketing theories for construction firms.

• 한국전산유체공학회지
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• 제13권4호
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• pp.39-44
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• 2008

Numerical simulations of laminar flow over a sphere are conducted to investigate the effect of the Reynolds number on the characteristics of vortex shedding. The Reynolds numbers considered are between 300 and 475, covering unsteady planar-symmetric and asymmetric flows. Results show that the unsteady planar-symmetric flow can be categorized into two different regimes: single-frequency regime and multiple-frequency regime. The former has a single frequency component due to periodic shedding of the vortices with the same strength in every shedding cycle, while the latter has multiple frequency components due to cycle-to-cycle variation in the strength of shed vortices with the shedding angle fixed. The multiple-frequency planar-symmetric flow, which is newly found in the present study, occurs at Re=330${\sim}$360 between the single-frequency planar-symmetric flow and the asymmetric flow. On the other hand, the asymmetric flow occurs at Re${\geq}$365, where the vortices shed from the sphere show variation both in strength and shedding angle unlike the planar-symmetric flow. Also, it is shown that the breaking of planar symmetry is closely related to the imbalance of vortical strength between a pair of streamwise vortices.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.656-661
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• 2007

현재의 주택시장의 양상은 과거와는 다르게 대부분의 건설사들이 자사만의 독자적인 네이밍으로 많은 아파트를 분양하고 있다. 그러나 이러한 아파트들을 소비자들에게 인지시켜 분양하는 과정에 있어서 차별적인 마케팅 전략이 존재하는 것이 아니라 경쟁사의 건축적 요소의 도입, 광고의 물량 공세 등 실질적인 마케팅 전략이 부재한 상황이다. 이로 인하여 소비자들은 각 아파트들의 차별성을 모르게 되고, 구입에 있어서도 혼선을 갖게 되었다. 이에 본 연구에서는 마케팅 이론에 근거한 브랜드 아파트의 전략을 제시하여 소비자들로 하여금 자사의 브랜드를 확실하게 인지시키는데 그 목적을 둔다.

• 대기
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• 제18권4호
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• pp.355-365
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• 2008

Synoptic and climatological characteristics of heat waves over Korea and Europe as well as their biometeorological impacts were compared. In July of 1994, excess deaths of about 2,388 in the population of South Korea are estimated by the modified excess death calculation algorithm ofKysely (2004). The excess deaths correspond to the net mortality increase of 12.5% in July of 1994 if we compare the estimated value to the expected number of deaths in this month (i.e., about 19,171). The comparative study of heat waves in Korea and Europe shows that the record-breaking heat waves in both regions are closely associated with prolonged droughts. In particular, reduction of soil moisture, precipitation and cloud cover and enhancement of insolation during the drought periods are very likely to be related to the increase in the intensity and the duration ofheat waves. Climate models predict that the frequency, intensity, and duration of heat waves in the 21 st century will be greatly enhanced in both areas. In order to reduce the biometeorological and socioeconomic impacts due to heat waves, not only the development of heat-related mortality prediction model that can be widely applied to many climate regimes, but also studies on the climatological association between extreme temperatures and abnormal hydrological cycle are needed.