• Tribology and Lubricants
• /
• 제12권1호
• /
• pp.22-28
• /
• 1996

This study was undertaken to investigate the dry wear characteristics and mechanism of KP-4M steel for plastic molding against SKD 61 hardened by heat treatment. The wear test was carried out under different conditions such as sliding speed, contact pressure, sliding distance, with frictional tester of pin on disc type. The wear loss on variation of sliding speed was little in lower speed range below 0.5 m/sec and in higher speed range above 1.5 m/sec,'but wear loss was high in intermediate speed range. The critical sliding speed, which showed the maximum value of specific wear rate, became lower with increased contact pressure. Increasing the contact pressure, the critical sliding distance Lcr which the wear mechanism changes from severe wear to mild wear was increased due to the decrease of oxidation reaction velocity. Through this study we suggested a model of generation and elimination process of wear debris of KP-4M steel for plastic molding.

• Journal of Species Research
• /
• 제5권3호
• /
• pp.443-458
• /
• 2016

Ten new species of genus Sarcotragus (Demospongiae: Dictyoceratida: Irciniidae) are described from Geomundo Island and Jejudo Island, Korea. All new species of the Sarcotragus are distinguished from the other reported species of Sarcotragus by the skeletal structure, especially fasciculate primary fibres. The characters of genus Sarcotragus have cylindrical primary fascicles filled with wads of filaments or flattened fascicles. All of the primary fibres are not cored with foreign debris. Secondary fibres have slightly fasciculate branch or plastic-like web. They are all not cored with foreign debris. All skeletal fibres are very irregular. The surface is covered with loose or tight filamentous membrane.

• Archives of Plastic Surgery
• /
• 제35권5호
• /
• pp.611-614
• /
• 2008

Purpose: Infection, foreign body reaction and decreased volume of implant are common complications after augmentation rhinoplasty with $Gore-tex^{(R)}$ implant. The author experienced two cases of recurrent foreign body granuloma in the patients who underwent $Gore-tex^{(R)}$ removal because of infection after augmentation rhinoplasty. and treated them with complete removal of$Gore-tex^{(R)}$. Methods: Case 1: A 49 year-old female visited our clinic for recurrent foreign body reaction on nasal dorsum and tip area. The patient underwent augmentation rhinoplasty with $Gore-tex^{(R)}$ 3 years ago and implant was removed due to infection 9 months ago. Excision of the granuloma was performed and a piece of foreign body suspicious to be a $Gore-tex^{(R)}$ implant debris was detected under the subcutaneous pocket. The implant fragments were removed and nasalis muscle rotation flap was performed to cover the lesion. The specimen was proved to be $Gore-tex^{(R)}$ in histological study. Case 2: A 31 year-old-male with recurrent foreign body granuloma on the nasal tip area visited our clinic. 10 years ago, the patient had augmentation rhinoplasty with silicone implant and then, he underwent revisional rhinoplasty five times including nasal implant removal, which was performed 9 months ago. The authors excised the granuloma and found a small sized foreign body suspicious to be a $Gore-tex^{(R)}$ implant debris under the granuloma. The foreign body was excised and identified to be $Gore-tex^{(R)}$ in histological study. Results: In both cases, the lesions were healed without any complications and there were no evidences of recurrence up to 6 months of follow-up. Conclusion: The $Gore-tex^{(R)}$ is known to be weak against mechanical force. These properties of $Gore-tex^{(R)}$ make it difficult to remove the implant completely. In the patient who have infection after augmentation rhinoplasty with $Gore-tex^{(R)}$, the operator should take care to perform the complete removal without remaining fragment of the implant.

• 수산해양교육연구
• /
• 제18권3호
• /
• pp.236-243
• /
• 2006

A series of surveys are performed to evaluate the abundance, composition and distribution of marine debris on the sea bed around the Busan port. In order to set up a master plan for the marine environmental pollution the relevant maritime authority must understand how many and w㏊t kinds of marine litters are distributed on the sea bed. At first we planed to survey areas divided regularly according to the coast line but there were many sea going vessels and fishing boats. So we selected and surveyed the around area where there were no sea going vessels or fishing boats.The obtained results are as follows: 1. The mean values of litters in number and weight are 5.8 pieces/㏊. and 3.5㎏/㏊. respectively. 2. The highest density in terms of number are vinyl and plastic item, and in weight are fishing gear and ship articles. 3. The nearer to the shore we surveyed the more we collected in terms of the density of marine litters in number and in weight per hectare. 4. Eel pot, oiled waste, rope, others, other pot and net of fishing gear litters in number were 59.9, 22.7, 7.9, 4.5, 3.1 and 1.9% respectively. 5. There is no relationship between the amount of fish caught and the amount of marine debris.

• 한국지반공학회논문집
• /
• 제33권12호
• /
• pp.7-20
• /
• 2017

본 연구에서는 전단특성 및 유변학적 정수를 모두 산정할 수 있는 직접전단실험 장비를 이용하여 조립토와 세립토에 대하여 전단강도 및 유변학적 특성에 대한 입도분포의 영향을 조사하고자 하였다. 최대입경 0.075mm의 세립토와 최대입경이 0.425mm이고, 세립분 함량이 17%인 조립토를 건조상태와 액성한계상태로 조성하여, 산사태 분류기준에 따라 재활성 산사태(reactivated landslide) 혹은 붕괴직후 토석류 속도에 해당하는 전단속도에 대하여 전단강도를 산정하였다. 또한, 유변학적 특성 평가를 위해 액성한계상태로 조성된 조립토와 세립토에 대하여 서로 다른 세 가지의 전단변형률속도로 반복적으로 전단하며 잔류전단강도를 측정하였다. 측정된 잔류전단강도와 전단변형률속도와의 관계를 통해 빙햄모델의 소성 점도와 항복응력을 산정하였다. 건조 및 액성한계상태에서 조성된 시료에 대하여 첨두전단강도에서 산정한 점착력의 경우, 세립토에서 조립토보다 더 크게 산정되었으며, 내부마찰각은 조립토에서 더 크게 산정되었다. 유변학 정수의 경우, 소성 점도와 항복응력이 조립토보다 세립토에서 더 큰 것으로 나타났다. 본 연구는 재활성 산사태 혹은 붕괴직후 토석류의 거동예측에 효과적으로 활용될 것으로 기대된다.

• Archives of Plastic Surgery
• /
• 제38권5호
• /
• pp.687-690
• /
• 2011

Purpose: Pemphigus vulgaris, a rare autoimmune blistering disease of the skin and mucous membranes remains a challenging disease to treat. Management is focused on immunotherapy against autoimmune antibodies that target keratinocyte cell adhesion molecules, and antibiotics preventing secondary infections. There is no established dressing protocol and skin is usually manipulated the least amount possible in order to minimize irritation. The authors suggest that early initiation of aggressive bathing and debridement of skin lesions, with nutritional support, is essential in accelerating resolution. Methods: A 40 year-old male previously diagnosed with pemphigus vulgaris was admitted due to exacerbation of mucocutaneous lesions involving the epidermis and mucosa of the whole body. Steroids, immunosuppressants, intravenous immunoglobulin and antibiotics were administrated, but infection and de-epithelialization progressed, while his general condition deteriorated with a weight loss of over 20 kilograms. The plastic surgery department intervened with daily bathing, debridement of unhealthy debris and non-traumatizing coverage of growing epithelium. Total parenteral nutrition and mobilization with rehabilitation therapy was initiated as early as possible. Results: After bathing, healthy epithelium gradually covered the patient's entire body, while his general condition improved with a corresponding weight gain of 14 kgs. Conclusion: Treatment of pemphigus vulgaris focuses on immunotherapy and infection control. However, an equal amount of attention should be laid on early intervention with daily dressings including bathing and irrigation, nutritional support, and exercise as this accelerates resolution of existing infections, promotes healthy epithelialization and leads to faster recovery.

• 한국재료학회지
• /
• 제15권12호
• /
• pp.824-828
• /
• 2005

In this study the effect of the content of $TiB_2$ on wear properties was investigated. $Cu-TiB_2$ composites have been fabricated by hot extrusion. Sliding wear tests were peformed by a pin-on-disk type wear test machine under dry condition and loads varied with from 20N to 80N at sliding speed 3.5Hz. The test results showed that the wear losses and the friction coefficients decreased with increasing $Cu-TiB_2$ volume fraction and increasing the size of $Cu-TiB_2$ particle. Wear property of $10{\mu}m,\;5 vol\%\; TiB_2$ specimen was excellent all of the wear specimens. It is thought that the increase of plastic flow resistivity due to uniform distribution of $10{\mu}m,\;5 vol\%\; TiB_2$ wear specimen would improve wear property. The worn surface and wear debris were examined by optical microscope and scanning electron microscope.

• 한국군사과학기술학회지
• /
• 제20권6호
• /
• pp.743-751
• /
• 2017

To evaluate the structural integrity of the helicopter radome, we performed bird strike analysis using SPH (Smoothed Particle Hydrodynamics) technique. Since the SPH method is a meshfree method, there is no phenomenon such as mesh tangling and it is suitable to predict the dispersion behavior of debris and debris cloud generated by high-speed impact. In order to observe the scattering direction of fractured bolts, the analysis were performed under the condition that the fracture occurs at the proof load. As a result of bird strike analysis, there is no secondary damage as well as the damage due to, the dispersion behavior of the bird model, and the scattering of the fractured bolts and radome. From the additional analysis that were performed to determine the actual bolt fracture, only plastic deformation is predicted since the maximum stress of the bolt does not exceed the ultimate stress.

• 대한토목학회논문집
• /
• 제34권4호
• /
• pp.1227-1240
• /
• 2014

휴 폐광산지역은 복합지질재해지역으로 집중호우에 의해 토사재해와 산성광산배수를 발생시킨다. 본 연구는 폐석적치장 전반에 걸쳐 토사재해가 관측된 임기광산에 대해 지반공학적 유변학적 시험을 수행하고 얻어진 시험결과를 토대로 1-D 토석류 수치해석을 수행함으로써 토석류의 확산성을 조사하였다. 모래와 자갈로 구성된 광산폐석 시료의 유변학적 특성을 조사하기 위해 베인관입형 레오미터(Vane-penetrated rheometer)를 사용하였으며, 전단응력 제어를 통한 전단응력(${\tau}$)-전단속도(${\dot{\gamma}}$)와 점도(${\eta}$)-전단속도(${\dot{\gamma}}$) 간의 상관관계를 얻었다. 또한 광산폐석 시료에 대해 잘 알려진 유변학적 모델들(Bingham, Herschel-Bulkley, Power-law, bilinear 및 Papanastasiou 모델)을 적용함으로써 수치해석에 필요한 유변학적 매개변수(항복응력과 소성점도)를 결정하였다. 실험결과에 따르면, 체적농도에 무관하게 전형적인 전단담화(shear thinning) 거동이 관측되었으며, 함수비가 증가할수록 Bingham 유체처럼 거동하는 것으로 나타났다. 또한 사용된 모든 유변학적 모델들은 파괴 후 거동에 적합한 모델들로 밝혀졌다. 토석류 흐름특성을 조사하기 위해 실험결과를 토대로 토석류 크기(5 m, 10 m 및 15 m)와 항복응력(100 Pa, 200 Pa, 300 Pa 및 500 Pa)을 선정하여 1-D BING을 통해 수치해석을 수행하였다. 그 결과, 토석류 이동거리와 이동속도는 항복응력의 크기에 반비례한 것으로 나타났으며, 토석류 항복응력이 500 Pa 이하인 경우 대부분의 토사는 계곡부까지 흘러갈 수 있는 것으로 나타났다. 따라서 집중호우 기간에 산악지역에 방치된 광산폐석은 토사재해에 취약하고 2차적으로 인근 수계로 유입되어 환경적 문제를 야기시킬 수 있는 것으로 나타났다.

• 식물병연구
• /
• 제7권2호
• /
• pp.107-111
• /
• 2001

조숙성 콩품종을 이용하는 풋콩 재배에서는 콩 미이라병과 자주무늬병에 의한 꼬투리 품질 저하와 종자콩의 확보문제가 큰 장애가 되고 있다. 콩 미이라병은 병든 식물의 잔사물이 중요한 제1차 전염원이며, 식물체에 감염하여도 살아 있는 조직에서는 균사의 생육이 극히 제한적이고, 잠재감염 상태로 포자형성이 거의 없으므로 이러한 병원균의 특성을 이용하는 재배적 방제의 가능성을 검토하였다. 점적관수는 분무관수에 비하여 무피복 재배에서는 종자감염율을 현저히 감소시켰으나 피복재배에서는 큰차이가 없었다. 피복재배는 콩 미이라병 28.0%, 자주무늬병 29.3%의 방제가를 보였으나 베노밀 방제가에는 미치지 못하였다. 식물체 잔사물 줄기의 78%는 7월초에 병포자가 성숙되어 제1차 전염원으로 작용하며, 당년의 식물체에서 탈락한 노화 떡잎과 염병에서도 7월 중순부터 9월에 걸쳐 충분한 제2차 전염원이 형성되었다 결론적으로, 비닐피복과 점적관수는 콩 수량성에 영향을 미치지 않고 어느 정도의 콩 미이라병과 자주무늬병 방제효과가 있으며, 제2차 전염원을 제거하는 포장위생관리의 병행은 방제효과를 더욱 제고시킬 것으로 보였다.